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Peptide reconstitution calculator

Enter your vial amount and desired dose to instantly calculate how many units to draw on your syringe. Works for any reconstituted peptide or premixed medication.

By OptiPin Editorial·Last updated ·Contact
How to use this calculator
1
Choose type
Powder vial or premixed liquid
2
Enter medication
Amount printed on your vial
3
Set liquid volume
How much BAC water you added
4
Enter your dose
Get exact syringe units instantly

Step 1 — What type of medication?

2

Medication in Vial

Enter the amount labeled on your vial(s)

3

Desired Dose per Injection

How much medication per injection

4

Reconstitution

Solve for

Bacteriostatic water added
2.00
mL
What liquid volume should I use?

Common choice: 1–3 mL. Most vials hold a max of ~3 mL.

• Less water → smaller injections, but harder to measure precisely

• More water → easier measurement, but larger injection volume

Always use bacteriostatic water (not saline or plain water) to preserve the peptide.

Enter your values above
Fill in the medication amount and desired dose to see your results.
Educational use only. This calculator is for informational purposes and does not constitute medical advice. Always verify dosing with your healthcare provider. Measurement errors can have serious health consequences — double-check your calculations.
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How to Use This Calculator

1
Choose your medication type

Reconstitute if you have a powder vial you'll mix with bacteriostatic water. Premixed if the medication already comes in liquid form.

2
Enter medication amount

For reconstitution: enter the mg amount printed on your vial (e.g., "5 mg BPC-157"). For premixed: enter the concentration listed (e.g., "200 mg/mL testosterone cypionate").

3
Enter your desired dose

Enter the dose you plan to inject each time (in mg or mcg).

4
Set water, or set your target units (reconstitution only)

Choose Set water → get units to enter how much bacteriostatic water you'll add and see the units to draw. Or flip to Set units → get water to pick a clean number of syringe units and have the calculator tell you how much water to add. 1–2 mL is common for most peptides.

Frequently Asked Questions

What is reconstitution?
Reconstitution means dissolving a freeze-dried (lyophilized) powder peptide into liquid — usually bacteriostatic water — to create an injectable solution. Most research peptides (BPC-157, TB-500, CJC-1295, etc.) come as powder and must be reconstituted before injection.
What does "units" mean on a syringe?
Insulin syringes measure in "units" — specifically insulin units. 100 units = 1 mL. So 10 units = 0.10 mL, 25 units = 0.25 mL. When you use an insulin syringe for peptides, you draw to the unit marking that corresponds to your calculated volume.
How much bacteriostatic water should I add?
Most practitioners use 1–2 mL for standard 5 mg peptide vials. Use this calculator to find the liquid volume that gives you an easy-to-measure number of units. For example, adding 2 mL to a 5 mg BPC-157 vial gives 2.5 mg/mL concentration. A 250 mcg dose = 10 units on a 30-unit syringe — a clean, easy measurement.
What syringe should I use?
30-unit (0.3 mL) insulin syringes are most commonly used for peptides. They allow precise measurement in small increments. 50-unit and 100-unit syringes are options if your dose requires a larger volume. Always use a fresh, sterile needle for each injection.
Can I use this for semaglutide / GLP-1 medications?
Yes — select Premixed mode and enter your concentration (e.g., 2.5 mg/mL or 5 mg/mL for compounded semaglutide, 2 mg/0.5 mL = 4 mg/mL for tirzepatide). Then enter your dose in mg. The calculator will give you the units to draw.