Peptide Reconstitution Calculator
Enter the vial strength, diluent volume, and dose specified for your prescribed medication. The calculator shows the corresponding volume and U-100 insulin syringe mark so you can review the math with your pharmacist.
The math, in plain English
Peptide reconstitution math has three steps. None of it is mysterious. Here is the same logic the calculator above is using, written out:
- 1
Find the concentration.
Take the milligrams of peptide that came in the vial, and divide by the milliliters of the specified diluent added. That gives you mg per mL. Arithmetic example only: a 10 mg vial with 2 mL of water gives 5 mg/mL, which is also 5,000 mcg/mL.
- 2
Find the volume per dose.
Divide your desired dose by the concentration. Same units on top and bottom. Example: 250 mcg ÷ 5,000 mcg/mL = 0.05 mL per dose.
- 3
Convert to insulin syringe units.
A standard U-100 insulin syringe is calibrated so 100 units fits in 1 mL. So multiply your volume in mL by 100. Example: 0.05 mL × 100 = 5 units. Easy.
About bacteriostatic water
Bacteriostatic water is sterile water with benzyl alcohol, a preservative that slows bacterial growth; it does not make a mixed medicine safe for a set number of days. Some medicines require preservative-free sterile water or a supplied diluent (mixing liquid). Use only the diluent and amount specified for your medication by its label or dispensing pharmacist.
Storage and discard dates are product specific
There is no universal shelf life for a reconstituted (mixed) peptide. Follow the medication label or dispensing pharmacist for storage and the discard date after mixing. Separately, CDC guidance says an opened, labeled multi-dose vial (a vial intended for repeated withdrawals) is generally dated and discarded within 28 days of first puncture unless its manufacturer specifies another date. For compounded sterile GLP-1 multidose vials, FDA recommends discarding within 28 days after first use even when the compounder gives a longer period. Neither rule establishes chemical stability or extends a shorter product-specific limit. Discard earlier if sterility is in doubt.
Important: this is a math tool, not medical advice
- The calculator does not decide whether you should take a peptide, what dose is right for you, or whether your specific vial is actually what the label says.
- This calculator shows volume arithmetic for a dose and dilution already specified by your prescriber or pharmacist. Confirm the vial strength, diluent, syringe type, and calculated volume with them before use. It does not choose a dose, dilution, product, or discard date.
- A vial sold for laboratory research is not a basis for human injection.
- If a result looks weird (very large or very small), recheck which unit you picked (mg vs mcg). Mixing them up is the most common mistake.
Common questions
What if my dose volume comes out to less than 1 unit?
The volume may be too small to measure accurately with that syringe. Do not change the dilution yourself; ask your pharmacist to review the prescription and measurement device.
What if my dose volume is more than 1 mL?
The volume does not fit in a single 1 mL syringe. Ask your prescriber or pharmacist how to proceed; do not change the dilution or split an injection on your own.
Does it matter what kind of syringe I use?
The unit math here assumes a U-100 insulin syringe, which is the standard. If you have a U-40 syringe (rare in the US, more common in some veterinary contexts), the unit math is different. Stick with U-100 unless you know exactly what you have.
How do I know my vial actually contains what the label says?
Confirm the product and labeled strength with the dispensing pharmacist. Compounded drugs are not FDA-approved, and a laboratory-only product should not be used as an injectable medicine.