Peptide Calculator: Reconstitution, Mixing & Dosing Made Simple
A precise peptide reconstitution calculator and peptide dose calculator that converts vial strength, bacteriostatic water volume, and your target dose into an exact syringe reading โ instantly, and for free.
Reconstitution & Dose Calculator
Works as a BPC-157 dosage calculator, a peptide calculator for tirzepatide, or any custom peptide โ just enter your own numbers.
Your Mix & Draw Results
Updates instantly as you change any value above.
๐ Syringe Fill Preview
๐ฅฏ Doses Remaining in Vial
๐ What-If: How Bacteriostatic Water Changes Your Draw
Scenario test โ see how much your syringe reading would change if you mixed the same vial with more or less water, at your current target dose.
๐ก What this means
Enter your numbers above to see a personalized explanation of your mix.
Peptide Reconstitution Chart (Reference)
Common vial-and-water combinations and the resulting concentration โ a quick-glance peptide mixing calculator table.
| Vial Size | Bac Water Added | Concentration | Units for 250 mcg | Units for 500 mcg |
|---|---|---|---|---|
| 2 mg | 1 mL | 2 mg/mL (2000 mcg/mL) | 12.5 units | 25 units |
| 5 mg | 1 mL | 5 mg/mL (5000 mcg/mL) | 5 units | 10 units |
| 5 mg | 2 mL | 2.5 mg/mL (2500 mcg/mL) | 10 units | 20 units |
| 5 mg | 3 mL | 1.67 mg/mL (1670 mcg/mL) | 15 units | 30 units |
| 10 mg | 2 mL | 5 mg/mL (5000 mcg/mL) | 5 units | 10 units |
| 10 mg | 3 mL | 3.33 mg/mL (3330 mcg/mL) | 7.5 units | 15 units |
Units shown assume a standard U-100 insulin syringe (100 units = 1 mL). Use the calculator above for your exact vial and dose.
What Is a Peptide Calculator?
A peptide calculator โ sometimes called a peptide calc, peptide reconstitution calculator, or informally a “Prime Peptide Calculator” after the popular category of tools โ converts three numbers you already have (the mg on the vial, the bacteriostatic water you added, and your target dose) into one number you actually need: the exact mark on your syringe. It replaces mental math and guesswork with a real-time, verifiable conversion.
The Reconstitution Formula
Every peptide reconstitution calculator, including this one, runs on the same core pharmacy math:
Volume to draw (mL) = Target dose (mcg) รท Concentration (mcg/mL)
Syringe units = Volume to draw (mL) ร 100 (for a U-100 insulin syringe)
This is the same dilution logic pharmacists use every day when compounding โ the calculator above simply automates it and shows you the result on a visual syringe.
Using This as a BPC-157 Dosage Calculator
BPC-157 is one of the most searched research peptides, typically supplied in 2โ5 mg vials. As of 2026, BPC-157 is not FDA-approved as a drug product; it is generally sold labeled “for research use only,” and its compounding status has been under active FDA review this year. Whatever your source or purpose, the math is identical: enter the vial strength and the bac water you used, choose “BPC-157” from the preset list, and the tool returns your exact draw volume and syringe reading โ it does not tell you what dose to use.
Peptide Calculator for Tirzepatide & Weight-Loss Peptides
Unlike BPC-157, tirzepatide is an FDA-approved prescription medicine (branded as Zepboundยฎ and Mounjaroยฎ) used under a clinician’s supervision, and compounded tirzepatide is only lawful when prepared by a licensed pharmacy under a valid prescription. When people search “peptide calculator mg for weight loss,” they’re usually reconstituting a compounded tirzepatide or semaglutide vial at home under their prescriber’s directions. Select the Tirzepatide preset, enter the vial mg from your pharmacy label and the water volume specified by your prescriber, and the calculator returns the syringe units for the dose your prescriber assigned โ always confirm the reading against your prescription before injecting.
Common Mixing Mistakes
- Confusing mg and mcg. Most peptide doses are written in micrograms (mcg), while vials are labeled in milligrams (mg) โ a 10x mix-up is the single most common dosing error.
- Misreading insulin syringe units. A U-100 syringe reads 100 units per mL; a U-40 syringe reads only 40 units per mL for the same volume โ using the wrong syringe type doubles or halves your actual dose.
- Ignoring dead space. Standard syringes retain a small amount of extra volume in the needle hub; this generally only matters for very low-dose, high-precision protocols.
- Not shaking or inverting gently after reconstitution. Swirl gently rather than shaking vigorously, which can damage the peptide structure.
Why Use a Digital Peptide Dosing Calculator Instead of Manual Math
A manual peptide dose calculator done on paper is where most measurement errors happen, especially when converting between mg, mcg, and syringe units at the same time. This tool performs all three conversions simultaneously, flags draws that are unusually small or large for standard syringes, and gives you a visual reference so you can double-check the number against the picture before you draw up a single unit.
Building out a full calculator suite? See the main DexoCalc calculator hub or browse the complete Health Calculators collection for related tools.
Frequently Asked Questions
Straight answers to the most common peptide reconstitution and dosing questions.
It’s a tool that converts a peptide vial’s strength (mg), the amount of bacteriostatic or sterile water you add, and your target dose into an exact volume and syringe reading, using the same mg/mL dilution math pharmacists use for compounding.
The math itself is exact โ concentration, volume, and syringe units are calculated to two decimal places. Real-world accuracy still depends on precisely measuring your water volume and reading the syringe correctly, since small measuring errors are magnified at low doses.
Select “BPC-157” from the peptide list, enter the mg printed on your vial and the bacteriostatic water you added, then enter your target dose in mcg. The tool returns the exact draw volume and syringe units โ it does not recommend a dose.
Yes. Choose the Tirzepatide preset, enter your vial’s labeled mg strength and the water volume specified by your prescriber or compounding pharmacy, and the calculator converts your prescribed dose into the correct syringe units for that specific vial.
A U-100 syringe measures 100 units per mL; a U-40 syringe measures only 40 units per mL. The same physical volume reads as a different unit number on each, so always match your syringe type in the calculator to the syringe you’re physically holding.
There’s no universal answer โ it depends on your protocol and the draw volume you want to work with. Less water creates a more concentrated mix (smaller draw volumes); more water dilutes it (larger, easier-to-measure draw volumes). Use the “What-If” scenario chart above to compare options before mixing.
No โ BPC-157 is not an FDA-approved drug product. It is typically sold labeled “for research use only,” and its future compounding status was under active FDA advisory review in 2026. This calculator provides math only and is not a statement about legality or safety.
Divide the total micrograms in the vial by your dose in micrograms โ for example, a 5 mg (5,000 mcg) vial at a 250 mcg dose yields 20 doses. The calculator does this automatically and also shows it as “days per vial” for once-daily protocols.
A very small draw usually means your mix is highly concentrated relative to your dose. Adding more bacteriostatic water dilutes the mix and increases the draw volume, which can make it easier to measure precisely on a standard syringe.
Yes โ use the “Copy results” button to copy a text summary to your clipboard, or the “Print” button to print or save the page as a PDF directly from your browser.
Yes, this tool is completely free, requires no sign-up, and runs entirely in your browser โ none of the numbers you enter are sent anywhere.
No. All calculations run locally in your browser using JavaScript. Nothing you type into this calculator is transmitted, stored, or logged.
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