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Functional calculator

Reconstitution calculator.

Live math for vial reconstitution. Enter what the vial says, how much bacteriostatic water you added, and your target dose — and the calculator returns the unit mark on a standard U-100 insulin syringe.

Free to use. No login, no email gate. The math is the math.

Your vial

The amount of peptide in the vial, before reconstitution
More water → easier to draw, lower concentration
In mg (e.g. 0.25 for 250 mcg starting semaglutide)
All assume U-100 insulin syringes (the standard)

What to draw

25
Units on your U-100 syringe
Concentration 2.5 mg/mL
Volume per dose 0.10 mL
Doses per vial 20
Mcg per dose 250 mcg

Syringe visual

0102030 40506070 8090100
Draw to the 25-unit mark.
The math:
concentration (mg/mL) = vial mg / bac water mL
volume per dose (mL) = target dose mg / concentration mg/mL
units on U-100 syringe = volume per dose × 100
doses per vial = vial mg / target dose
Honest notes

Read this before you draw.

Source matters more than math.

The math is the easy part. The harder question — is the vial real, sterile, correctly labelled — is the one this calculator cannot answer. Use 503A compounding pharmacies, not research-chemical resellers.

U-100 syringes assume 100 units per mL.

If you accidentally use a non-U-100 (tuberculin, 1cc) syringe with mL markings, the unit conversion does not apply. Confirm "U-100" on the syringe wrapper before you draw.

Storage and stability.

Most reconstituted GLP-1s are stable refrigerated for ~28 days. Most reconstituted growth-hormone-releasing peptides are stable ~30 days refrigerated. Read the specific compound profile for exact numbers.

Not medical advice

This calculator is a math tool. It is not a recommendation to use any compound. The decision to reconstitute a peptide and inject yourself with it belongs to you and a clinician who knows your full medical history — not to a webpage.

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