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.
Mixing two or more peptides in one vial? → Peptide Blend calculator
Each page shows the exact unit marks to draw for that peptide's most common vial sizes and doses — no calculator math required.
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.
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.
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.
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.
Bacteriostatic water (BAC water) is sterile water that contains 0.9% benzyl alcohol as a preservative. The benzyl alcohol prevents bacterial growth, so a single vial can be used for multiple injections over 28 days without contamination. Plain sterile water has no preservative — once you puncture it, it should be used immediately. For multi-dose peptide vials, BAC water is the standard.
Most peptides are stable for 28 days at 2–8°C (refrigerated) once reconstituted with bacteriostatic water — that's the FDA stability standard for benzyl-alcohol-preserved solutions. Some fragile peptides (e.g., BPC-157, Thymosin Beta-4) degrade faster and are typically used within 14–21 days. Always check the manufacturer's stability data for your specific peptide.
U-100 syringes are calibrated so 100 units = 1 mL. U-50 syringes are 50 units = 0.5 mL (just a smaller version with finer increments). For most peptide doses, U-100 1 mL syringes (29–31 gauge, 8–13 mm needles) are standard. Use U-50 if you need finer increments for micro-dosing (e.g., 0.05 mL fractions of a 1 mg/mL solution).
Sterile saline (0.9% NaCl) works for single-use injections but contains no preservative — once you pierce the vial, it should be discarded within 24 hours. Plain sterile water is the same. For multi-dose vials kept refrigerated for weeks, you need bacteriostatic water (0.9% benzyl alcohol). Don't use tap water, bottled water, or distilled water — they aren't sterile.
Each tick mark on a U-100 insulin syringe is 1 unit = 0.01 mL. So '10 units' on the syringe = 0.10 mL of solution. The calculator above converts your target dose (e.g., 250 mcg) into the number of unit marks you need to draw based on your peptide concentration. The visual bar shows the exact fill level on a standard 100-unit syringe.
Less BAC water = more concentrated solution = smaller draw volume per dose (good for thick peptides but harder to dose precisely). More BAC water = dilute solution = larger draw volume (easier to measure but takes up more syringe space). The peptide itself doesn't degrade either way — only the unit-mark math changes. The calculator above lets you experiment with both before reconstituting.
Gentle swirl only — never shake or vortex. Most therapeutic peptides are fragile proteins that denature under mechanical stress (foaming, vigorous shaking). Add BAC water slowly down the inside wall of the vial, then swirl gently until fully dissolved. If a peptide doesn't dissolve after a few minutes of gentle motion, let it sit at room temperature for 15–30 minutes — most will go into solution on their own.