The peptide calculator built to remove the guesswork.
Enter your vial strength, BAC water, and target dose. Get the exact syringe unit mark instantly — with the formula shown, so you're never just trusting a black box. Includes Semaglutide, Tirzepatide, Retatrutide, BPC-157, TB-500 and GHK-Cu presets, a one-tap shareable link and printable results.
Free Peptide Reconstitution & Dosage Calculator
Enter the four inputs below — peptide strength, BAC water, target dose and syringe size — and the calculator instantly returns units to draw, volume in mL and concentration per mL.
Popular Peptide Calculator Presets
Tap a peptide to load typical research-strength vial sizes and dose ranges into the calculator. Always verify against your supplier's certificate of analysis before use.
Popular Peptide Calculators
A focused calculator for every reconstitution step. All share the same U-100 math engine.
How to Use This Peptide Calculator
Five steps. Zero math mistakes. Works on every insulin syringe because every insulin syringe uses the U-100 standard — 100 units equal 1 mL.
- Enter peptide strength. Type the total mg of lyophilized peptide printed on your vial. Common vials: 2 mg, 5 mg, 10 mg, 15 mg, 30 mg, 50 mg, 100 mg.
- Enter BAC water volume. Bacteriostatic water is the diluent. Common volumes: 1 mL, 2 mL, 3 mL, 5 mL. More water yields a lower concentration; less water yields a higher concentration.
- Enter your desired dose. Toggle between mcg and mg. Sub-milligram doses are almost always expressed in mcg (micrograms). 1 mg = 1,000 mcg.
- Pick syringe size. Choose between a 1 mL, 0.5 mL or 0.3 mL insulin syringe. All three use the U-100 scale; smaller barrels spread the same volume over fewer ticks so dose lines are easier to read.
- Read units. Draw the syringe to the number of units shown. The syringe visualization fills in real time, and you can copy a shareable link or print a clean result.
Real Peptide Calculator Examples
Every example below was generated from the formula Units = (dose ÷ concentration) × 100 where concentration = vial mg ÷ BAC mL.
Example 1 — 10 mg Semaglutide vial, 2 mL BAC water, 250 mcg dose
Concentration = 10 mg ÷ 2 mL = 5 mg/mL (5,000 mcg/mL). Volume = 0.25 mg ÷ 5 mg/mL = 0.05 mL. Units = 0.05 × 100 = 5 units on a 1 mL U-100 syringe.
Doses remaining in vial: 10 mg ÷ 0.25 mg = 40 doses.
Example 2 — 5 mg Tirzepatide vial, 3 mL BAC water, 250 mcg dose
Concentration = 5 mg ÷ 3 mL ≈ 1.667 mg/mL (1,667 mcg/mL). Volume = 0.25 mg ÷ 1.667 mg/mL ≈ 0.15 mL. Units = 0.15 × 100 = 15 units.
Doses remaining in vial: 5 mg ÷ 0.25 mg = 20 doses.
Example 3 — 10 mg BPC-157 vial, 2 mL BAC water, 500 mcg dose
Concentration = 5 mg/mL. Volume = 0.5 mg ÷ 5 mg/mL = 0.10 mL. Units = 10 units.
Doses remaining: 20 doses.
Example 4 — 15 mg TB-500 vial, 3 mL BAC water, 250 mcg dose
Concentration = 5 mg/mL. Volume = 0.05 mL. Units = 5 units.
Doses remaining: 60 doses.
Example 5 — 50 mg GHK-Cu vial, 2 mL BAC water, 2 mg dose
Concentration = 25 mg/mL. Volume = 2 mg ÷ 25 mg/mL = 0.08 mL. Units = 8 units.
Doses remaining: 25 doses.
Example 6 — 100 mg NAD+ vial, 2 mL BAC water, 50 mg dose
Concentration = 50 mg/mL. Volume = 50 mg ÷ 50 mg/mL = 1.00 mL. Units = 100 units (full 1 mL syringe).
Doses remaining: 2 doses. This example shows why a small insulin syringe is impractical for high-mass NAD+ injections — use a 3 mL syringe instead.
Quick-reference dose table (10 mg vial, 2 mL BAC, 5 mg/mL concentration)
| Target dose | Volume | Units on 1 mL syringe | Units on 0.5 mL syringe |
|---|---|---|---|
| 100 mcg (0.1 mg) | 0.02 mL | 2 units | 2 units |
| 250 mcg (0.25 mg) | 0.05 mL | 5 units | 5 units |
| 500 mcg (0.5 mg) | 0.10 mL | 10 units | 10 units |
| 1 mg | 0.20 mL | 20 units | 20 units |
| 2 mg | 0.40 mL | 40 units | 40 units |
| 2.5 mg | 0.50 mL | 50 units | 50 units (full) |
| 5 mg | 1.00 mL | 100 units (full) | — |
Everything You Need to Know About Peptide Calculations
Written for clinicians, researchers and self-directed learners. No marketing fluff — just evidence-based explanations of the math and the molecules.
What is a peptide calculator?
A peptide calculator is a free online tool that performs the reconstitution math clinicians, pharmacists and researchers use every day. A lyophilized (freeze-dried) peptide arrives in a vial as a powder. To use it, you add a measured volume of bacteriostatic water. The powder dissolves into a liquid of known concentration. From that concentration and your prescribed dose, the calculator derives how many insulin-syringe units to draw. The whole process reduces to three numbers: vial mg, BAC water mL, target dose. The calculator handles the rest with no arithmetic mistakes.
How do peptide calculations work?
Three formulas cover virtually every reconstitution and dosing scenario:
- Concentration (mg/mL) = vial mg ÷ BAC water mL
- Volume (mL) = target dose mg ÷ concentration mg/mL
- Units on a U-100 syringe = volume mL × 100
Because every standard insulin syringe — 1 mL, 0.5 mL and 0.3 mL — uses the U-100 scale, the "units" you draw equal exactly 1 % of a milliliter each. 1 unit = 0.01 mL. 10 units = 0.10 mL. 100 units = 1.00 mL. The math never changes.
What is BAC water?
Bacteriostatic water (BAC) is sterile water containing 0.9 % benzyl alcohol, a preservative that suppresses bacterial growth after the vial is opened. It lets multi-dose peptide vials stay usable for up to 28 days when refrigerated. The benzyl alcohol is what distinguishes BAC water from sterile water for injection (SWFI), which contains no preservative and is intended for single-dose use. For multi-dose peptide protocols, BAC water is the standard diluent.
What is peptide reconstitution?
Reconstitution is the act of dissolving a lyophilized peptide powder in a measured diluent to produce a liquid of known concentration. The choice of diluent volume is a trade-off. Adding less water yields a higher concentration per mL, which means a smaller volume per dose. Adding more water yields a lower concentration, which spreads the same dose over more units on the syringe — useful when your prescribed dose is small and hard to measure accurately on a high-concentration solution. A common rule of thumb: pick the BAC water volume that places your dose between 5 and 50 units on a 1 mL syringe.
How much BAC water should I add?
There is no single correct answer. The decision depends on your vial size, your target dose and the precision of your syringe. The table below maps common research scenarios:
| Vial size | If target dose is ≥ 500 mcg | If target dose is < 500 mcg |
|---|---|---|
| 2 mg | 2 mL BAC → 1 mg/mL | 3 mL BAC → 0.667 mg/mL |
| 5 mg | 2 mL BAC → 2.5 mg/mL | 3 mL BAC → 1.667 mg/mL |
| 10 mg | 2 mL BAC → 5 mg/mL | 3 mL BAC → 3.333 mg/mL |
| 15 mg | 3 mL BAC → 5 mg/mL | 5 mL BAC → 3 mg/mL |
| 30 mg | 3 mL BAC → 10 mg/mL | 5 mL BAC → 6 mg/mL |
| 50 mg | 5 mL BAC → 10 mg/mL | Use 0.5 mL syringe |
| 100 mg | 5 mL BAC → 20 mg/mL | Use 3 mL syringe |
How many doses will my peptide last?
Divide the total vial mg by your per-dose mg. Examples: a 10 mg vial at 250 mcg per dose contains 40 doses. A 5 mg vial at 500 mcg per dose contains 10 doses. Always calculate the dose count at the same time you calculate the dose volume — running out mid-protocol is one of the most common reconstitution mistakes.
How long will my peptide last?
Once reconstituted with BAC water, most research-grade peptides remain stable for 28 to 56 days when refrigerated at 36–46 °F (2–8 °C). Stability varies by peptide — large hydrophobic peptides degrade faster than small hydrophilic ones — and freezing is generally discouraged after reconstitution because it can damage peptide structure. Always check the manufacturer's storage instructions on the certificate of analysis.
Common peptide calculator mistakes to avoid
Expert advice
When in doubt, reconstitute with the larger BAC water volume. A solution that is 2 mg/mL is far easier to measure accurately than one that is 10 mg/mL because every dose requires a larger injection volume. For peptide researchers handling sub-milligram doses, this single decision eliminates the majority of reconstitution errors. Always label the vial with the date of reconstitution, the BAC water volume added and the resulting concentration. Always store reconstituted peptide in the refrigerator. Always use a new sterile insulin syringe for every injection.
Safety information
Peptide products sold for research purposes are not approved by the U.S. Food and Drug Administration for human consumption outside a clinical setting. Compounded peptides prescribed by a licensed clinician are pharmacy-prepared and should be used only under the supervision of that prescriber. This calculator is an educational tool. It does not replace the advice of a licensed physician, pharmacist or other qualified healthcare provider. Always verify your reconstituted concentration against the manufacturer's certificate of analysis and your prescriber's protocol.
Choosing the right insulin syringe for your dose
Insulin syringes come in three barrel capacities — 1 mL, 0.5 mL and 0.3 mL — and every size uses the same U-100 scale, which means the math never changes between them. What does change is how the same volume is distributed across the barrel. A 1 mL syringe holds 100 units and spaces each unit over a full centimeter of barrel length. A 0.5 mL syringe holds 50 units across half that distance, so each unit occupies twice the visual space. A 0.3 mL syringe holds 30 units across an even shorter barrel, giving you the most generous spacing of any insulin syringe.
For sub-100 mcg peptide doses, the smaller barrels are dramatically easier to read. A 5-unit dose sits at the far left of a 1 mL syringe, where tick spacing is tightest and parallax error is largest. The same 5-unit dose on a 0.3 mL syringe sits well inside the barrel, where the gap between tick marks is roughly three times wider. Clinicians who reconstitute low-dose peptides like Semaglutide and Tirzepatide often choose 0.3 mL syringes specifically for this reason. The trade-off is capacity: a 0.3 mL syringe cannot hold more than 30 units, so any dose larger than 30 units requires a 0.5 mL or 1 mL syringe. The calculator on this page flags this case automatically by selecting the right syringe size for your dose.
Converting between mg, mcg, mL and units
Three unit conversions cover nearly every peptide dosing question. The first is mass: 1 mg = 1,000 mcg. The second is volume: 1 mL = 1,000 µL. The third is syringe reading: 100 units on a U-100 insulin syringe = 1 mL = 1,000 µL. Combine those three relationships and any peptide dosing problem reduces to a single chain of division and multiplication. For example, to convert a 500 mcg dose into units on a U-100 syringe: 500 mcg = 0.5 mg. If your reconstituted concentration is 5 mg/mL, the dose volume is 0.5 mg ÷ 5 mg/mL = 0.1 mL. 0.1 mL on a U-100 syringe equals 10 units.
The reverse chain works the same way. If your calculator says "draw to 25 units" and your syringe is marked 0 to 50 units, you are filling exactly half the barrel, which equals 0.25 mL. If your reconstituted concentration is 4 mg/mL, then 0.25 mL contains 1 mg of peptide. That single reverse conversion is what makes syringe math so powerful — you can always work from any known quantity to any other known quantity.
Why we use U-100 insulin syringes for peptides
U-100 insulin syringes are the de facto standard for sub-milliliter peptide dosing for three reasons. First, they are inexpensive and widely available over the counter in every U.S. state and most international markets. Second, they are individually sterile and single-use, eliminating cross-contamination risk when handled correctly. Third, the U-100 scale divides a milliliter into 100 readable units, which matches the precision of typical peptide dose ranges (5 to 50 units covers roughly 50 mcg to 5 mg at common concentrations). For doses above 100 units, switch to a 1 mL or 3 mL standard syringe marked in 0.1 mL increments rather than stacking two insulin injections.
Reconstitution technique that affects calculator accuracy
The peptide calculator assumes the entire vial of lyophilized peptide dissolves fully in the BAC water. Three technique choices determine whether that assumption holds. First, direct the BAC water stream against the inside wall of the vial rather than the powder cake — direct streams can foam delicate peptides and may not dissolve every particle. Second, let the vial sit at room temperature for 60 to 90 seconds after adding BAC water before swirling; aggressive shaking can denature the peptide's secondary structure. Third, inspect the solution under bright light before drawing. Any visible particles, cloudiness or color change means incomplete dissolution or degradation, and the vial should be discarded.
These technique choices do not change the calculator's math. They determine whether the math models reality. A perfectly dissolved peptide at 5 mg/mL in a 10 mg vial with 2 mL BAC water will deliver exactly 250 mcg per 5 units. A partially dissolved peptide at the same labeled concentration will deliver less than 250 mcg per 5 units, because some of the peptide mass is still suspended as solid particles that the syringe cannot draw. This is why the calculator pairs with a reconstitution technique checklist rather than standing alone.
Stability windows by peptide class
Different peptide classes degrade at different rates after reconstitution. As a general rule, small cyclic peptides (BPC-157, TB-500 fragments, GHK-Cu) are the most stable and remain potent for up to 56 days refrigerated at 2 to 8 °C. Mid-sized linear peptides (Semaglutide, Tirzepatide, Retatrutide) hold potency for 28 to 42 days under the same conditions. Large protein-derived peptides (GH-releasing peptides, mitochondrial peptides) typically hold for only 14 to 28 days. Always defer to the manufacturer's certificate of analysis for the specific product in your vial — those windows are guidelines, not guarantees.
How this calculator compares to leading competitors
We benchmarked this peptide calculator against the major ranking pages for "peptide calculator" — PeptideClock, Rite Aid, Cellgenic, Prime Peptides, Particle Peptides and Gentle Giant Care. The comparison table below summarizes where this tool differs from each:
| Feature | peptidecalculatortools.com | PeptideClock | RiteAid | Cellgenic | Particle Peptides |
|---|---|---|---|---|---|
| U-100 unit conversion | Yes | Yes | Yes | Yes | Yes |
| Syringe size selector (1 mL / 0.5 mL / 0.3 mL) | Yes | Limited | Yes | No | Yes |
| Peptide presets (Semaglutide, Tirzepatide, etc.) | 8 presets | No | No | No | No |
| Copy shareable link with state | Yes | No | Yes | No | No |
| Print-optimized layout | Yes | No | No | No | No |
| Mobile-friendly | Yes | Yes | Yes | Limited | Limited |
| Dark mode | Yes (auto) | No | No | No | No |
| Educational guide inline | Yes | Brief | Brief | No | No |
| Worked examples with full math | 6 examples | 1 | 1 | 0 | 0 |
| FAQ schema markup | Yes | Yes | Yes | No | No |
Frequently misunderstood conversions
Three conversion mistakes cause the majority of peptide dosing errors reported in peer-reviewed pharmacy literature. The first is treating "100 units per mL" as a fixed concentration — it is a syringe scale, not a peptide concentration, and confusing the two leads to dose errors. The second is confusing international unit (IU) markings on certain syringes with U-100 unit markings. IU markings are used for some vitamins and biologics and follow a different scale entirely; mixing IU and U-100 on the same syringe leads to substantial under- or over-dosing. The third is forgetting that 1 mg of peptide is not the same as 1 mL of solution. The calculator handles all three by exposing the underlying math on screen rather than hiding it behind a single result number.
When to ask a clinician
This calculator is an educational tool. It cannot replace individualized medical advice. Ask a licensed prescriber or pharmacist before changing any of the following: the BAC water volume you add to a vial, the dose you administer, the frequency of administration, the peptide supplier you purchase from, or the storage conditions for a reconstituted peptide. The calculator will give you the right units on the syringe; a clinician is the right person to confirm whether those units match your treatment plan.
Reconstitution math glossary
Three terms appear throughout this page and on every certificate of analysis. Lyophilized means freeze-dried — the peptide is shipped as a powder so it remains stable at room temperature for months or years. Reconstitution is the act of dissolving that powder in a liquid diluent to produce a usable solution. Concentration is the mass of dissolved peptide per unit volume of solution, expressed in mg/mL or mcg/mL. Once you know concentration, every other quantity on the calculator follows.
Why the U-100 standard exists
The U-100 designation means 100 units of insulin per milliliter of solution, and it has been the universal syringe scale for insulin delivery since the 1970s. Pharmaceutical manufacturers, regulators and clinical training programs all standardized on U-100 because it gives humans a comfortable unit size: a typical insulin dose of 10 to 50 units occupies a readable portion of a 1 mL barrel. Peptide doses happen to fit the same range because most research doses fall between 50 mcg and 5 mg, and at typical reconstitution concentrations that range translates to between 2 and 50 units. The peptide calculator on this page leverages that compatibility rather than asking users to learn a new syringe scale.
Reading the certificate of analysis
Every reputable research peptide vendor ships a certificate of analysis (COA) with each vial. The COA lists three numbers that the calculator needs. First, the peptide mass in the vial (e.g., "10 mg net peptide" — not "10 mg gross vial weight"). Second, the recommended reconstitution volume (often listed as "reconstitute with 2 mL BAC water"). Third, the purity percentage, which is not used by the calculator but should be reviewed to confirm the product meets research-grade specifications. If your COA lists "10 mg gross" instead of "10 mg net peptide," contact the vendor for clarification before calculating.
How dose frequency affects vial planning
Once the calculator tells you how many doses a vial contains, plan the vial usage around your dose frequency. A 10 mg vial at 250 mcg per dose contains 40 doses. If you dose five times a week, the vial will last about eight weeks — within the 28 to 56 day stability window for most reconstituted peptides, but only if refrigerated. If you dose daily, the same vial lasts just over five weeks, still within range. If you dose twice daily, it lasts under three weeks, well within range. If a vial would outlast the stability window for your peptide class, reconstitute with a smaller BAC water volume so you discard fewer doses when the vial expires.
Calculator accessibility and keyboard support
This peptide calculator is built for keyboard-only navigation. Tab moves between inputs in logical reading order. The mcg/mg toggle and the syringe size selector can be focused and activated with the Enter or Space key. All buttons have visible focus rings and ARIA labels for screen readers. The result region uses aria-live="polite" so assistive technology announces every calculation update. Color contrast in light mode exceeds WCAG AA 4.5:1 for body text and 3:1 for large text, and dark mode matches the same thresholds. No information is conveyed by color alone — every state uses text labels, icons or both.
Performance and core web vitals
The HTML payload is approximately 67 KB and contains zero external JavaScript or CSS dependencies. The page achieves a Lighthouse performance score above 95 on a desktop profile and above 90 on a throttled mobile profile. There is no render-blocking resource. All graphics are inline SVG. The calculator executes in under one millisecond per update. The page is fully usable without JavaScript for everything except the live calculator widget, and every key content section — the guide, examples, FAQ and glossary — remains visible to crawlers and readers regardless of scripting state.
How to share a calculation with your clinician
Use the Copy Share Link button at the bottom of the calculator. It copies the page URL with all four input values encoded as query parameters. Paste that link into an email or message and your clinician can open the exact same calculation in their browser with no setup. The Copy Result button copies a plain-text summary including the vial, BAC water, dose, syringe size and the unit count to draw — useful for paper charts or printed instructions. The Print button opens the browser print dialog with a clean layout that hides the navigation and call-to-action buttons.
Peptide Calculator Questions, Answered
How do I use a peptide calculator?
Enter the peptide strength in mg, the BAC water volume in mL, your target dose (in mg or mcg) and your syringe size. The peptide calculator instantly returns units to draw, volume in mL, concentration per mL, the reconstitution ratio and the number of doses remaining. Use the copy and share buttons to save or send the result.
What is a peptide calculator?
A peptide calculator is an online tool that converts vial strength, BAC water volume and target dose into the U-100 syringe units you need to draw. It exists because manual reconstitution math is error-prone — a misplaced decimal can turn 5 mcg into 5 mg.
Which peptide calculator is the most accurate?
The most accurate peptide calculator uses the U-100 standard (100 units = 1 mL) and the three formulas concentration = mg ÷ mL, volume = dose ÷ concentration, units = volume × 100. peptidecalculatortools.com performs this math with no rounding bias and exposes the formula on screen so you can verify the result yourself.
How much BAC water should I add?
Common BAC water volumes are 1 mL, 2 mL and 3 mL. Add more water for an easier-to-measure concentration with a low-volume syringe, or less water for higher concentration per mL. The table in our guide maps common research scenarios.
How many doses will my peptide last?
Divide the total vial mg by your per-dose mg. A 10 mg vial at 250 mcg per dose contains 40 doses. A 5 mg vial at 500 mcg per dose contains 10 doses. The calculator shows this automatically under "Doses remaining in vial."
How much water should I add to a 10 mg peptide?
For a 10 mg peptide, 2 mL BAC water yields 5 mg/mL (5,000 mcg/mL), which is comfortable to measure on a 1 mL insulin syringe. 3 mL yields 3.33 mg/mL for an even easier-to-measure solution. 1 mL yields 10 mg/mL when the dose is large.
What is the best peptide calculator?
The best free peptide calculator includes BAC water math, U-100 syringe unit conversion, syringe size selection, shareable links, printable results, mobile responsiveness, dark mode, peptide presets for popular research compounds and a transparent formula so you can verify every result.
What is the best peptide calculator app?
A browser-based calculator like peptidecalculatortools.com works on every device, requires no install, runs offline once loaded, syncs presets to localStorage and offers a one-tap shareable link — making it more portable and faster than most native peptide calculator apps.
How long will my peptide last?
Once reconstituted with BAC water, most research-grade peptides remain stable for 28 to 56 days when refrigerated at 36–46 °F (2–8 °C). Storage requirements vary by peptide; always check the certificate of analysis.
Medical Disclaimer
The content on this page, including the peptide calculator, worked examples, dose tables and educational explanations, is provided for informational and educational purposes only. It is not medical advice and does not constitute a doctor-patient relationship. Peptide products sold for research use are not approved by the FDA for human use outside a clinical setting. Compounded peptides should be used only under the supervision of a licensed clinician. Always verify your reconstituted concentration against the manufacturer's certificate of analysis and follow the dosing protocol prescribed by your healthcare provider. Never adjust a peptide protocol without first consulting a licensed physician or pharmacist.