Heart Score Calculator
Home / Weight Loss & Peptides / Peptide Reconstitution Calculator
3 Calculation Modes · 17+ Peptide Presets · mcg/mg Toggle

Peptide Reconstitution
Calculator:
BAC Water, Syringe Units
& Dose Planner

Whether you need to calculate exactly how much bacteriostatic water to add to your peptide vial, convert a mcg dose to U-100 syringe units, or plan a complete weekly injection schedule — the Heart Score Calculator peptide reconstitution tool does all three in one place. Supports BPC-157, TB-500, CJC-1295, Ipamorelin, GHK-Cu, and 12 more research peptides with pre-loaded typical vial sizes and doses. Free, no sign-up, instant results.

What Makes This the Best Free Peptide Reconstitution Calculator

Most online peptide calculators only do one direction: enter vial and water, get units. We built 3 complete modes: standard reconstitution (concentration → units), reverse BAC water calculator (target units → water needed), and a multi-dose planner that maps your entire vial across weeks and flags stability expiry. Plus mcg/mg dual-input, a live syringe visual, and 17+ peptide presets. The most accurate peptide dosage calculator you will find — all free.

3
Calc Modes
17+
Peptide Presets
mcg/mg
Dual Unit Input
Free
No Sign-up
⚠️ Research Use Disclaimer

This calculator is provided for educational and informational purposes. Research peptides are intended for laboratory and in vitro study only. They are not approved for human consumption or therapeutic use in most jurisdictions unless prescribed by a licensed physician. Always comply with local regulations. This tool does not constitute medical advice.

Peptide Reconstitution Calculator

Peer-Reviewed Formula

Enter your vial size, how much BAC water you are adding, and your target dose. Get exact syringe units, mL draw, and concentration.

Total mg in your lyophilised vial

mL of bacteriostatic water

e.g. 250 mcg = 0.25 mg

Know your target syringe units? Enter vial size, your dose, and desired units — we calculate exactly how much BAC water to add.

How many units you want to draw per injection

Plan your full vial protocol. Enter vial size, BAC water, dose, and injection frequency — get a weekly schedule with stability expiry flags.

Concentration
Draw Volume
Syringe Units
Doses / Vial
U-100 Insulin Syringe — Fill Level
0102030405060708090100 units
Complete the calculation above
mg/mL
mL Draw
Units
mcg/Unit
Dose (mcg / mg) Draw Volume (mL) Syringe Units Doses/Vial
Stable up to 28 days refrigerated (2–8°C) after reconstitution.

Always verify your vial's declared mass against the Certificate of Analysis (CoA) before calculating. Measure BAC water with a calibrated syringe. Small measurement errors propagate as dosing errors across every injection.

Peptide Reconstitution Formulas — The Complete Calculation Guide

peptide reconstitution calculator insulin syringe barrel unit markings
Figure 1: Macro vector illustration of a U-100 insulin syringe barrel. Zoomed-in view showing clear unit markings from 0 to 100 units.

At its core, every peptide reconstitution calculation rests on three linked formulas. Understanding these formulas means you can verify any calculator's output by hand, catch errors before they affect your protocol, and adapt quickly when you need to change vial sizes or target doses mid-research. The Heart Score Calculator applies these exact formulas across all three calculation modes.

Formula 1 — Peptide Concentration (the Foundation)

When you add bacteriostatic water to a lyophilised peptide vial, you are creating a solution with a specific concentration — measured in milligrams per millilitre (mg/mL). This single value drives every downstream calculation. Get this right and everything else follows. This is also called the peptide dilution formula or the peptide mixing ratio.

Peptide Concentration Formula
Concentration (mg/mL) = Vial Size (mg) ÷ BAC Water Added (mL)
// 5mg vial + 2mL BAC water = 5 ÷ 2 = 2.5 mg/mL
// 10mg vial + 2mL BAC water = 10 ÷ 2 = 5.0 mg/mL
// 2mg vial + 1mL BAC water = 2 ÷ 1 = 2.0 mg/mL

Formula 2 — Draw Volume and mg to mL Peptide Conversion

Once you know the concentration, you can calculate how much solution to draw into your syringe for each dose. This is the peptide solution calculator formula that most tools implement. The result is in millilitres (mL), which then gets converted to U-100 syringe units by multiplying by 100. For a general-purpose mg to mL calculator covering any medication or liquid, our dedicated tool handles a wider range of substances beyond peptides.

Peptide Draw Volume + Syringe Unit Conversion
Draw Volume (mL) = Dose (mg) ÷ Concentration (mg/mL)
Syringe Units (U-100) = Draw Volume (mL) × 100
// 250mcg (0.25mg) dose at 2.5mg/mL = 0.25÷2.5 = 0.1mL = 10 units
// 500mcg (0.5mg) dose at 5.0mg/mL = 0.5÷5.0 = 0.1mL = 10 units
// ⚠ Same unit count, different vials — always verify concentration

Formula 3 — Reverse BAC Water Calculator

The reverse calculation is unique to our tool among free online peptide reconstitution calculators. It answers the question: "I want to draw exactly 20 units for my dose — how much BAC water should I add?" This is especially useful for researchers who prefer working with a specific, consistent syringe unit count across their entire protocol.

Reverse BAC Water Formula — Target Units → Water Volume
Required Concentration = (Dose mg × 100) ÷ Target Units
BAC Water (mL) = Vial Size (mg) ÷ Required Concentration
// Want 20 units for 500mcg (0.5mg) from 10mg vial:
// Required conc = (0.5 × 100) ÷ 20 = 2.5 mg/mL
// BAC water = 10 ÷ 2.5 = 4mL → Add 4mL to vial

Peptide Reconstitution Quick Reference Table

This peptide dosage chart shows the most common reconstitution scenarios. Each row shows a vial size and BAC water combination with the resulting concentration and unit counts for standard research doses. Use it as a quick cross-check against our peptide reconstitution calculator above.

Vial BAC Water Concentration 100 mcg = 250 mcg = 500 mcg = 1,000 mcg =
1 mg1 mL1 mg/mL10 units25 units50 units100 units
2 mg1 mL2 mg/mL5 units12.5 units25 units50 units
5 mg1 mL5 mg/mL2 units5 units10 units20 units
5 mg2 mL2.5 mg/mL4 units10 units20 units40 units
5 mg5 mL1 mg/mL10 units25 units50 units100 units
10 mg2 mL5 mg/mL2 units5 units10 units20 units
10 mg4 mL2.5 mg/mL4 units10 units20 units40 units
15 mg3 mL5 mg/mL2 units5 units10 units20 units
30 mg3 mL10 mg/mL1 unit2.5 units5 units10 units

All values for U-100 insulin syringes (1mL = 100 units). Dose in mcg. Verify with our calculator for exact values at non-standard vial sizes.

How to Reconstitute Peptides — Step-by-Step Protocol

Reconstituting lyophilised peptides correctly is not complicated, but it requires precision, aseptic technique, and patience. Errors during reconstitution — whether from contamination, incorrect solvent volumes, or aggressive mixing — cascade through every subsequent measurement and can render an entire vial useless. Follow this standard operating procedure every time.

1
Calculate Before You Open Anything

Before touching any equipment, use the peptide reconstitution calculator above to determine your exact BAC water volume. Write down the resulting concentration (mg/mL), draw volume (mL), and syringe units. Having these numbers confirmed before opening vials prevents rushed, error-prone recalculation under time pressure. Confirm the vial mass against the Certificate of Analysis from your supplier.

2
Prepare a Clean Workspace

Wash hands thoroughly with soap and water for at least 20 seconds. If available, wear sterile gloves and work in a laminar flow hood or near a recently cleaned surface. Lay out all supplies: lyophilised peptide vial, bacteriostatic water vial, U-100 insulin syringes, alcohol swabs (70% isopropyl), and labelling supplies. Cleanliness at this stage is the most effective contamination prevention measure available.

3
Swab Both Vial Stoppers

Using a fresh alcohol swab, wipe the rubber stopper of both the peptide vial and the BAC water vial. Allow 15–30 seconds for the alcohol to fully evaporate before piercing — injecting through wet alcohol introduces it into the solution. Never reuse a swab between vials. If the peptide vial came vacuum-sealed, check that the stopper is intact before proceeding.

4
Draw the Calculated BAC Water Volume

Using a calibrated insulin syringe, draw your calculated BAC water volume from the BAC water vial. To equalise pressure, first draw air equal to your target volume, insert the needle into the BAC water vial, inject the air, and then withdraw the liquid. Remove any air bubbles by tapping the syringe barrel gently and expelling them. Precision here is critical — a 10% error in BAC water volume means a 10% concentration error in every dose that follows.

5
Inject BAC Water Slowly Down the Vial Wall

Insert the needle through the peptide vial stopper at a slight angle so the tip touches the inside glass wall — not the powder cake. Inject the BAC water slowly so it trickles down the glass wall onto the powder. Never forcefully inject the liquid directly onto the lyophilised powder. The impact of a pressurised stream can mechanically damage the peptide structure and cause aggregation. This is the step most commonly skipped incorrectly by new researchers.

6
Gently Swirl — Never Shake

After adding BAC water, gently swirl the vial in slow circular motions for 1–5 minutes until the powder is fully dissolved and the solution is completely clear and colourless. Never shake vigorously, vortex, or use a stir bar — mechanical agitation denatures peptide bonds and causes aggregation. Research confirms that vigorous agitation significantly increases peptide degradation (Manning et al., 1989, PMID 2664067). If the solution remains cloudy after 10 minutes of gentle swirling, or develops visible particles or colour change, discard the vial.

7
Label and Refrigerate Immediately

Write the reconstitution date, peptide name, and concentration (e.g. "BPC-157 — 2.5mg/mL — Reconstituted 20 May 2026") directly on the vial. Refrigerate at 2–8°C (36–46°F) immediately. Most research peptides are stable for 28–30 days after reconstitution in BAC water when stored refrigerated and protected from light. Never freeze a reconstituted solution. Check the stability window in the peptide reference table below and plan your injection schedule accordingly.

BAC Water vs Sterile Water for Peptide Reconstitution — Which to Use?

The choice of solvent for peptide reconstitution directly affects how long your solution remains usable and how safely you can make multiple draws from the same vial. For any protocol involving more than a single injection from a reconstituted vial — which is the overwhelming majority of research protocols — bacteriostatic water (BAC water) is the correct choice.

The core difference: BAC water contains 0.9% benzyl alcohol as a preservative. This antimicrobial agent inhibits bacterial growth across multiple vial punctures over 28–30 days. Sterile water has no preservative. The moment you open a sterile water vial and draw from it, any subsequent draw risks contaminating the entire contents with environmental bacteria. For a vial you plan to inject from daily for 2–4 weeks, sterile water creates unacceptable contamination risk.

When to Use BAC Water

Use bacteriostatic water (BAC water) for any multi-dose research protocol where you will draw from the same vial more than once over days or weeks. BAC water is the standard for BPC-157, TB-500, CJC-1295, Ipamorelin, GHRP-2, GHK-Cu, PT-141, and virtually all other common research peptides. It maintains antimicrobial protection for 28–30 days and is compatible with U-100 insulin syringes of any gauge.

⚠️
When Sterile Water May Be Used

Sterile water is only appropriate for single-use preparations where the entire reconstituted volume will be used in one session. It is also used as a first-step solvent for highly hydrophobic or charged peptides that require dilute acetic acid or DMSO for initial dissolution before dilution with BAC water. Certain protein-based compounds may also be incompatible with benzyl alcohol — always check your specific compound's solubility notes.

🌡️
Storage Temperature Matters

Even with BAC water's benzyl alcohol preservative, proper refrigeration is non-negotiable. Room temperature storage dramatically accelerates peptide degradation — especially for temperature-sensitive compounds like IGF-1 LR3 and sermorelin. Store reconstituted vials in the main body of the refrigerator (not the door), where temperature fluctuations are minimal, and protected from light in a small box or bag.

🔬
Confirming Peptide Quality

Always request a Certificate of Analysis (CoA) from any peptide supplier — specifically one showing HPLC purity and mass spectrometry confirmation of molecular weight. A reputable CoA from an independent laboratory verifies that the vial contains the declared compound at the stated purity and mass. This is the starting assumption of every accurate peptide reconstitution calculation — if the vial mass is not what the label says, every unit count will be wrong.

Common Research Peptides — Vial Sizes, Typical Doses & Stability Reference

peptide reconstitution calculator peptide reconstitution infographic
Figure 2: Professional clinical infographic layout, 4-step horizontal process for peptide reconstitution.

The following peptide reconstitution guide covers the most widely researched peptides, with typical lyophilised vial sizes, common research dose ranges, and post-reconstitution stability windows. Use these as starting reference points for our peptide administration calculator above — the presets are pre-loaded with these values. Body composition and fitness calculators like our BMI Calculator and VO2 Max Calculator can help researchers track the physiological context alongside peptide protocol timelines.

Peptide Typical Vial (mg) Typical Dose (mcg) Freq Stability (BAC) Notes
BPC-1575 mg200–500 mcg1–2×/day28–30 daysStable in BAC water; most popular healing peptide
TB-500 (Thymosin β4)5–10 mg2,000–5,000 mcg2×/week28–30 daysHigher dose compound; wide therapeutic window
CJC-1295 (no DAC)2–5 mg100–300 mcgBefore sleep21 daysOften combined with Ipamorelin (1:1 ratio)
Ipamorelin5 mg100–300 mcg1–3×/day28 daysSelective GH secretagogue; minimal side effects
GHK-Cu1–5 mg50–200 mcg1×/day28 daysCopper peptide; often used topically or subcutaneously
PT-141 (Bremelanotide)10 mg500–2,000 mcgAs needed28 daysMC4R agonist; administer 45 min before use
GHRP-25 mg100–300 mcg3×/day28 daysStrong GH secretagogue; increases ghrelin significantly
GHRP-65 mg100–300 mcg3×/day28 daysSignificant hunger increase; potent GH release
Hexarelin5 mg100–200 mcg2–3×/day28 daysMost potent GHRP; receptor desensitisation common
Sermorelin15 mg200–500 mcgBefore sleep14–21 daysShort stability; use within 2–3 weeks of reconstitution
IGF-1 LR31 mg20–100 mcgDaily14 daysFragile; freeze pre-diluted aliquots. Requires care
Selank5 mg250–500 mcg1–2×/day28 daysAnxiolytic peptide; also used intranasally
Semax30 mg200–600 mcg1–2×/day30 daysNootropic peptide; intranasal or subcutaneous
Epitalon10 mg500–1,000 mcgDaily cycle28 daysTelomerase activator; typically 10-day cycles
Kisspeptin-102 mg50–100 mcgProtocol-specific14–21 daysGnRH regulator; research context only
SS-31 (Elamipretide)5 mg50–200 mcgDaily21 daysMitochondria-targeting peptide

Typical doses are reference ranges from published research literature — not clinical recommendations. Stability windows for BAC water reconstitution stored at 2–8°C. Always follow the specific protocol for your research model.

If your research involves GLP-1 receptor agonist peptides like semaglutide or tirzepatide, those require separate calculators due to their distinct dosing in milligrams and brand-specific formulations — our Semaglutide Dosage Calculator and Tirzepatide Calculator cover those compounds in full detail.

Peptide Storage After Reconstitution — Stability Guide

peptide reconstitution calculator medical icon set peptide storage
Figure 3: Minimalist medical icon set for peptide storage. Icons: 1. Refrigerator with thermometer (2-8°C), 2.

Knowing how long reconstituted peptides last is not optional — miscalculating your vial's stability window means injecting degraded, potentially ineffective compound. The table below provides guidance on peptide storage conditions and post-reconstitution shelf life. This information is essential when planning your multi-dose schedule using Mode 3 in our simple peptide reconstitution calculator.

Storage Condition Lyophilised (Unreconstituted) Reconstituted in BAC Water Notes
Room temperature (20–25°C)Weeks–months (dry, dark)24–72 hours onlyNot recommended for reconstituted solution
Refrigerated (2–8°C)Months28–30 daysStandard storage for active use
Frozen (−20°C)1–2 yearsDo NOT freezeFreeze-thaw damages reconstituted solution
Frozen (−80°C)2–5 yearsDo NOT freezeFor long-term lyophilised storage only
Refrigerated (IGF-1 LR3)Months at −20°C14 days maxFragile; pre-aliquot before reconstitution
Exposed to lightDegradedDegraded fasterAlways store in opaque container or foil-wrapped vial

Never freeze a reconstituted peptide solution. Ice crystals that form during freezing physically shear peptide bonds and cause irreversible aggregation. If you cannot use an entire reconstituted vial within the stability window, the recommended approach is to reconstitute into smaller aliquots (separate vials) and freeze those while still in lyophilised form — then reconstitute individual aliquots as needed. This is particularly important for expensive compounds like IGF-1 LR3.

How the Peptide Reconstitution Calculator Works — Behind the Maths

The best peptide reconstitution calculator does not just give you a number — it shows its work. Every calculation the Heart Score Calculator peptide tool performs displays a full formula breakdown so you can verify the result manually at any time. This transparency is particularly important for research applications where reproducibility matters.

The calculator supports mcg (micrograms) and mg (milligrams) dose input interchangeably. Converting peptide mg to mcg is simply multiplying by 1,000 — and the tool handles this automatically so you can work in whatever unit your protocol specifies. For broader medication dose conversions covering a wider range of substances and clinical concentrations, the mg to mL Calculator provides a comprehensive general-purpose tool.

The multi-dose planner mode is where this calculator genuinely outperforms all competitors. After entering your vial size, BAC water volume, dose, and injection frequency, the planner generates a complete weekly schedule table and automatically flags weeks where your peptide solution approaches or exceeds its stability window. This prevents the common research error of planning a 6-week protocol from a single reconstituted vial that only remains stable for 4 weeks.

For those researching metabolic peptides and their effects on body composition, pairing the results from this calculator with our TDEE Calculator for total daily energy expenditure and our GFR Calculator for kidney function monitoring creates a comprehensive physiological tracking framework.

Peptide Reconstitution Calculator — 20 Frequently Asked Questions

What is peptide reconstitution? +
Peptide reconstitution is the process of dissolving lyophilised (freeze-dried) peptide powder into a liquid solution suitable for injection or research use. Peptides are supplied as dry powder because the lyophilised form is far more stable during shipping and storage than a liquid solution. To use the peptide, you dissolve the powder in a precisely calculated volume of bacteriostatic water (BAC water) or another appropriate sterile solvent to create a solution with a known concentration in mg/mL. The resulting solution is then drawn into a syringe for administration.
How do you calculate peptide reconstitution step by step? +
Step 1: Confirm your vial mass in mg from the Certificate of Analysis. Step 2: Decide how much BAC water to add — choose a volume that gives you a clean unit count on your syringe. Step 3: Calculate concentration: Vial mg ÷ BAC water mL = concentration in mg/mL. Step 4: Calculate draw volume: Dose mg ÷ Concentration mg/mL = mL to draw. Step 5: Convert to U-100 syringe units: mL × 100 = units. Example: 5mg vial + 2mL BAC water = 2.5mg/mL. For a 250mcg (0.25mg) dose: 0.25 ÷ 2.5 = 0.1mL × 100 = 10 units. Use Mode 1 in our peptide reconstitution calculator above to do this automatically.
How much BAC water should I add to a peptide vial? +
There is no universally fixed amount — it depends entirely on your vial size and target dose. The practical approach is to choose a BAC water volume that results in a draw volume you can measure comfortably on your syringe (ideally 5–30 units on a U-100 syringe). Very low unit counts (1–3 units) are difficult to measure accurately; very high unit counts (80–100 units for a single dose) mean large injection volumes. For a 5mg vial and a 250mcg dose, 2mL BAC water gives 2.5mg/mL and 10 units — a clean, practical draw. Use our reverse BAC water calculator (Mode 2) to find the exact water volume for any target unit count.
What is the difference between BAC water and sterile water for peptides? +
Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol which prevents bacterial growth across multiple draws from the same vial. It keeps reconstituted peptides stable for 28–30 days refrigerated and is the correct choice for any multi-dose protocol. Sterile water has no preservative and must be used in a single session — the moment you open a sterile water vial and draw from it, subsequent draws risk contamination. For virtually all research peptide protocols involving daily or weekly injections from a single vial, BAC water is required.
How many units is 250mcg on an insulin syringe? +
This depends entirely on your reconstitution concentration — there is no fixed answer. At 1.0mg/mL: 250mcg = 25 units. At 2.5mg/mL: 250mcg = 10 units. At 5.0mg/mL: 250mcg = 5 units. The unit count changes completely with every different BAC water volume you use. Never assume a unit count without knowing your specific concentration. This is exactly why a peptide dosage reconstitution calculator is essential — always confirm your concentration before drawing.
How long do reconstituted peptides last in the fridge? +
Most research peptides reconstituted in bacteriostatic water remain stable for 28–30 days when stored refrigerated at 2–8°C and protected from light. Some exceptions: IGF-1 LR3 is more fragile and should be used within 14 days. Sermorelin is relatively unstable and should be used within 14–21 days. Semax and TB-500 can remain stable for up to 4–6 weeks under optimal conditions. Always discard reconstituted solution if it becomes cloudy, discoloured, or develops visible particles — any of these signs indicate degradation or contamination.
Can you reconstitute peptides with sterile water instead of BAC water? +
Sterile water is only appropriate if you will use the entire reconstituted volume in a single session. Without the benzyl alcohol preservative in BAC water, any repeated draws over days or weeks risk bacterial contamination that degrades the peptide and creates safety concerns. For any multi-dose protocol — which covers the vast majority of research applications — BAC water is the only appropriate solvent. Certain very hydrophobic or charged peptides may need an alternative first-step solvent (dilute acetic acid, DMSO) before dilution with BAC water, but sterile water alone is not a routine multi-dose substitute.
Why should you never shake a peptide vial? +
Vigorous shaking causes mechanical agitation that damages peptide bonds through shear force. This process — called shear denaturation — causes peptide molecules to unfold and aggregate. Research by Manning et al. (1989) demonstrated that physical agitation significantly increases aggregation in reconstituted peptide solutions (PMID: 2664067). Shaking also creates foam and bubbles that introduce oxygen, accelerating oxidative degradation. Always dissolve peptides by gently swirling the vial in slow circular motions — never shake, vortex, or stir. If the powder does not dissolve within 10 minutes of gentle swirling, something is wrong with the vial or the solvent.
How do you convert peptide mg to mcg? +
To convert milligrams to micrograms, multiply by 1,000. To convert micrograms to milligrams, divide by 1,000. Common conversions: 0.1mg = 100mcg. 0.25mg = 250mcg. 0.5mg = 500mcg. 1mg = 1,000mcg. 5mg = 5,000mcg. Most research peptides (BPC-157, TB-500, CJC-1295) are dosed in micrograms, while GLP-1 weight-loss compounds (semaglutide, tirzepatide, retatrutide) are dosed in milligrams. Our peptide reconstitution and dosage calculator lets you toggle between mcg and mg input using the dose unit buttons at the top of the calculator.
What is the peptide concentration formula? +
The peptide concentration formula is: Concentration (mg/mL) = Total peptide in vial (mg) ÷ BAC water added (mL). This is the fundamental calculation that every subsequent dosing decision depends on. For example: a 10mg vial dissolved in 2mL BAC water = 5mg/mL. This means every 1mL of solution contains 5mg of peptide, every 0.1mL contains 0.5mg (500mcg), and on a U-100 syringe, 10 units delivers 0.5mg (500mcg). The peptide dilution guide above shows this calculation applied across all common vial sizes and BAC water volumes.
How do you use a U-100 insulin syringe for peptide injections? +
U-100 insulin syringes are the standard for subcutaneous peptide injections. Key facts: 1mL = 100 units on a U-100 syringe. To find your unit count: Units = (Dose mg ÷ Concentration mg/mL) × 100. Draw the calculated number of units from the reconstituted vial after swabbing the stopper with alcohol. For subcutaneous injection: pinch a fold of skin at the injection site (abdomen, thigh, or upper arm), insert at 45–90°, inject slowly, withdraw, apply gentle pressure. Rotate injection sites. Use 29–31 gauge, 6–8mm needles for comfort with subcutaneous SC protocol.
What is the reverse BAC water calculation and when do you use it? +
The reverse BAC water calculation answers: "How much BAC water should I add to achieve exactly X units on my syringe for my dose?" It is useful when you want a consistent, easily-readable unit count across a long protocol. Formula: Required Concentration (mg/mL) = (Dose mg × 100) ÷ Target units. BAC Water needed (mL) = Vial mg ÷ Required concentration. Example: You want exactly 25 units for 500mcg (0.5mg) from a 10mg vial. Required conc = (0.5 × 100) ÷ 25 = 2.0mg/mL. BAC water = 10 ÷ 2.0 = 5mL. Add 5mL BAC water to the vial. This feature is available in Mode 2 of our peptide reconstitution calculator.
How do you store peptides after reconstitution? +
After reconstitution, store peptide solutions in the refrigerator at 2–8°C (36–46°F), protected from light. Label every vial with the reconstitution date, peptide name, and concentration. Most peptides are stable for 28–30 days in these conditions. Never freeze reconstituted solutions — freeze-thaw cycles cause irreversible aggregation and loss of activity. Keep vials in the main body of the refrigerator where temperature is most stable, not in the door. Before each draw, visually inspect for cloudiness, particles, or colour change — discard immediately if any are present.
What peptides work best reconstituted with BAC water? +
The vast majority of research peptides reconstitute readily and stably in bacteriostatic water. This includes: BPC-157, TB-500, CJC-1295, Ipamorelin, GHRP-2, GHRP-6, Hexarelin, GHK-Cu, PT-141, Selank, Semax, Epitalon, Kisspeptin-10, SS-31, and Sermorelin. Some highly hydrophobic sequences or very acidic/basic peptides may require a small amount of dilute acetic acid (0.1% acetic acid) or DMSO for initial dissolution, followed by dilution to the working concentration with BAC water. Your supplier's CoA and solubility notes should specify if the compound has special solvent requirements.
How do you calculate how many doses are in a peptide vial? +
Doses per vial = Vial size (mg) ÷ Dose per injection (mg). Always convert mcg to mg first: divide by 1,000. Example: 10mg vial, 500mcg (0.5mg) per injection: 10 ÷ 0.5 = 20 doses. Check that total doses × interval days falls within your peptide's stability window. If 20 doses injected every other day = 40 days but stability is 28 days, you will not be able to use the last 6 doses before the solution degrades. Our multi-dose planner (Mode 3) calculates this automatically and generates a weekly schedule with stability flags.
Can I freeze reconstituted peptides to extend shelf life? +
No — never freeze a reconstituted peptide solution. Freeze-thaw cycles cause ice crystal formation that physically shears peptide bonds and creates irreversible aggregation and loss of bioactivity. If you need longer storage than the 28–30 day refrigerated window, the correct approach is to freeze the peptide before reconstitution (as lyophilised powder at −20°C) and reconstitute only the portion you plan to use within the stability period. Alternatively, create multiple small vial aliquots of the dry powder and reconstitute one at a time as needed.
What happens if I add too much BAC water to a peptide? +
Adding too much BAC water creates a more dilute concentration, which means you need to draw a larger volume per dose to hit your target. The peptide compound itself is not harmed — dilution affects the injection volume but not the peptide's molecular structure or activity. The main practical concerns are: larger injection volumes can be uncomfortable for subcutaneous administration, and with a dilute solution, measurement precision on the syringe becomes more important (small errors represent a higher percentage of the dose). If you have already added too much water, use the reverse calculator (Mode 2) to recalculate your units at the new concentration.
How accurate is an online peptide reconstitution calculator? +
The arithmetic in any correctly-programmed peptide reconstitution calculator is exact — the formula has no approximation. The limiting factor for accuracy in practice is measurement precision: specifically, (1) whether your vial contains the declared mass (always check against CoA), and (2) whether you measure BAC water precisely with a calibrated syringe. A 5% error in BAC water volume (e.g. drawing 1.9mL instead of 2.0mL) creates a 5% concentration error that compounds across every dose in your protocol. Use a fine-gauge insulin syringe — not a tablespoon or graduated dropper — for BAC water measurement.
What is the difference between mg and mcg in peptide dosing? +
Milligrams (mg) and micrograms (mcg) are different units of mass: 1mg = 1,000mcg. Research peptides like BPC-157, TB-500, and CJC-1295 are typically dosed in micrograms (100–5,000mcg). GLP-1 metabolic compounds like semaglutide and tirzepatide are dosed in milligrams (0.25–15mg). Confusing mg with mcg creates a 1,000-fold error — treating 1mg as 1mcg means a 1,000× underdose; treating 1mcg as 1mg means a 1,000× overdose. Our peptide dosage calculator supports both units with a clearly-labelled toggle button, and displays both values in results to prevent confusion.
Do I need a different calculator for GLP-1 peptides like semaglutide or retatrutide? +
Yes. GLP-1 receptor agonists like semaglutide (Ozempic/Wegovy), tirzepatide (Mounjaro/Zepbound), and retatrutide are dosed in milligrams (0.25–15mg), have different reconstitution protocols, and follow clinical titration schedules that differ significantly from research peptides. For those compounds, we have dedicated calculators: our Semaglutide Dosage Calculator covers Ozempic, Wegovy, and compounded semaglutide, while the Tirzepatide Calculator covers Mounjaro, Zepbound, and compounded tirzepatide — both with full reconstitution, mg-to-units, weight loss projection, and protein intake modes. The retatrutide calculator covers the newer GLP-1/GIP/glucagon triple agonist. This peptide reconstitution calculator is optimised for the mcg-dosed research peptides in the reference table above.

Peptide Reconstitution — Key Takeaways

Concentration (mg/mL) = Vial mg ÷ BAC water mL. This one number drives every dosing decision — get it right before drawing.
Syringe units are not fixed — the same dose produces different unit counts at different concentrations. Always recalculate when changing BAC water volume.
Never shake, vortex, or aggressively stir a reconstituted peptide — swirl gently until clear. Agitation causes irreversible aggregation.
Refrigerate at 2–8°C immediately after reconstitution. Most peptides are stable for 28–30 days. Never freeze the reconstituted solution.
Use BAC water (bacteriostatic water) for all multi-dose protocols. Sterile water is single-use only and unsuitable for vials you will draw from repeatedly.
Cardiovascular & Metabolic Health Specialist

All formulas and protocols in this peptide reconstitution calculator are sourced from peer-reviewed pharmaceutical preparation literature: Manning et al. (1989, PMID 2664067), GenScript peptide dissolution guidelines, Sigma-Aldrich synthetic peptide storage protocols, and Bachem AG reconstitution guidelines. This tool is provided for educational and research reference purposes. It does not constitute medical advice.