Getting your peptide dosage right isn’t just about following a number — it’s about understanding what you’re mixing, why it matters, and how to do it safely. Whether you’re working with GLP-1 compounds like semaglutide and tirzepatide, or peptides like BPC-157 and TB-500, even a small miscalculation can throw off your entire protocol.
This peptide calculator is built to take the guesswork out of reconstitution and dosing. Enter your vial size, bacteriostatic water volume, and target dose — and you’ll get an accurate, ready-to-use result in seconds.
Peptide Calculator
1. Target Dose (mg)⚠️ Medical Disclaimer
This peptide calculator is intended for informational and research reference purposes only. It does not constitute medical advice. Semaglutide and tirzepatide are FDA-approved prescription medications available only through a licensed physician. BPC-157 and TB-500 are research compounds not approved for human use by the FDA.. Always consult a licensed physician or pharmacist before reconstituting, dosing, or injecting any peptide. Incorrect dosing can cause serious harm. NextGenCalculators.com accepts no liability for decisions made based on this tool.
What Is a Peptide Reconstitution Calculator?
When lyophilized (freeze-dried) peptides arrive as powder, they need to be mixed with bacteriostatic water before use. This process is called reconstitution, and the ratio of peptide to water determines the concentration of every injection you’ll draw afterward.
A peptide reconstitution calculator does one simple but critical thing: it tells you exactly how many units (IU) or milliliters to draw into your syringe to hit your intended dose in milligrams or micrograms. This is especially important when working with compounds that come in varying vial sizes — a 5 mg semaglutide vial reconstituted with 1 mL of water gives you a very different concentration than the same vial mixed with 2 mL.
Semaglutide Reconstitution Calculator
Semaglutide is one of the most commonly reconstituted GLP-1 peptides, and the math can trip people up quickly. The standard approach is to add bacteriostatic water to the vial, then calculate what volume equals your weekly dose.
For example, if you have a 5 mg semaglutide vial and add 2 mL of bacteriostatic water, your concentration becomes 2.5 mg/mL. A 0.25 mg starting dose would then require you to draw just 0.1 mL (10 units on a U-100 insulin syringe).
Our semaglutide mixing calculator handles this automatically. Just input your vial size and water volume, and it outputs the exact draw volume for any dose — no manual math needed. It works equally well whether you’re using a 2.5 mg, 5 mg, or 10 mg semaglutide vial.
If you’re tracking metabolic health, it’s helpful to check your levels using an A1C calculator for a clearer picture of blood sugar trends.
Tirzepatide Reconstitution Calculator
Tirzepatide follows the same reconstitution logic as semaglutide but often comes in larger vial sizes — 10 mg, 15 mg, 30 mg, and even 60 mg — which is where users frequently run into calculation errors.
With a 30 mg tirzepatide vial, for instance, the choice of how much bacteriostatic water you add dramatically changes your concentration and draw volume. Adding 3 mL gives you a 10 mg/mL solution. Adding 1.5 mL doubles the concentration to 20 mg/mL — meaning you’d draw half the volume for the same dose.
Our tirzepatide mixing calculator accounts for these variations. Whether you’re titrating up from a 2.5 mg starting dose or working with higher weekly amounts, you’ll get a precise injection volume every time.
BPC-157 Dosage Calculator
BPC-157 is measured differently from GLP-1 peptides. Most protocols work in micrograms (mcg) rather than milligrams, which makes the math feel unfamiliar at first. A common research dose runs between 250 mcg and 500 mcg per injection, and BPC-157 typically comes in 5 mg vials.
Using a BPC-157 dosage calculator removes the unit conversion headache. If you reconstitute a 5 mg (5,000 mcg) vial with 2 mL of bacteriostatic water, your concentration is 2,500 mcg/mL. A 500 mcg dose equals 0.2 mL, or 20 units on a U-100 syringe.
This same logic applies to the BPC-157 and TB-500 blend, which many people use together. A blend dosage calculator lets you input both peptides’ concentrations and target doses simultaneously, giving you a single combined draw volume — simplifying a protocol that would otherwise require two separate calculations.
How to Use This Peptide Calculator
Using the calculator is straightforward. Here’s the process:
- Select your peptide — semaglutide, tirzepatide, BPC-157, TB-500, or another compound
- Enter your vial size — in mg (e.g., 5 mg, 10 mg, 30 mg)
- Enter your bacteriostatic water volume — in mL (e.g., 1 mL, 2 mL, 3 mL)
- Enter your target dose — in mg or mcg
- Get your result — the calculator displays your draw volume in mL and IU
That’s it. No spreadsheets, no manual conversions, no guesswork.
Peptide Dosage in IU vs. mg — Understanding the Difference
One of the most common sources of confusion is the difference between IU (International Units) and mg (milligrams) when measuring peptide doses. On a standard U-100 insulin syringe, 1 IU equals 0.01 mL. So when someone says “draw 20 IU,” that’s the same as 0.2 mL.
Our peptide calculator in IU and mg makes this conversion transparent. You can enter your dose in either unit and see both outputs, which is especially useful when switching between syringe types or working from protocols written in different formats.
Frequently Asked Questions
What is a peptide reconstitution calculator used for?
It calculates the exact volume of bacteriostatic water to mix with a lyophilized peptide vial, then tells you how many mL or IU to draw for a specific dose. This prevents under- or over-dosing caused by incorrect concentration math.
How do I use a semaglutide reconstitution calculator?
Enter your vial size (e.g., 5 mg), the volume of bacteriostatic water you’re adding (e.g., 2 mL), and your target dose. The calculator will output the precise draw volume — typically in mL and syringe units.
How much peptide should I take?
Dosage depends entirely on the specific peptide, your body weight, and the protocol you’re following. Always defer to a licensed medical provider for dosing guidance. A calculator helps you measure accurately once a dose has been determined — it doesn’t determine the dose for you.
Can I calculate BPC-157 and TB-500 blend dosages together?
Yes. A blend dosage calculator lets you input the concentration and dose for each peptide separately, then combines them into a single draw volume — useful when both peptides are in the same vial or when stacking them in one injection.
What’s the difference between a peptide dosage calculator and a reconstitution calculator?
A reconstitution calculator helps you mix the vial correctly (water-to-powder ratio). A dosage calculator tells you how much to draw per injection. Most tools combine both functions into one — as this calculator does.
Does tirzepatide vial size affect my dose calculation?
Yes, significantly. A 30 mg vial mixed with 3 mL of water has a different concentration than the same vial mixed with 1.5 mL. Always use a tirzepatide reconstitution calculator when changing vial sizes or water volumes to avoid dosing errors.
Is this calculator free to use?
Yes. This is a completely free peptide calculator — no sign-up, no paywall, no download required.