What this calculator does
A peptide reconstitution calculator turns three numbers off your vial and prescription — the peptide amount, the water you add, and your dose — into the exact units to draw on a U-100 syringe. It’s a units converter, not a dosing guide: it tells you where to pull the plunger to for a dose you’ve already been given, nothing more.
Reconstitution is the step where a freeze-dried (lyophilized) peptide powder is dissolved in bacteriostatic water so it can be drawn into a syringe. The confusing part is that the same dose can land at completely different points on the syringe depending on how much water you added — which is exactly what this tool sorts out.
How the math works
Three steps, and the calculator runs all of them:
1. Concentration = peptide (mg) ÷ water (mL) 2. Volume = your dose (mg) ÷ concentration (mg/mL) 3. Units = volume (mL) × 100
Worked example — a 10 mg vial, 2 mL of water, a 250 mcg dose:
- Concentration: 10 mg ÷ 2 mL = 5 mg/mL
- Your dose in mg: 250 mcg = 0.25 mg
- Volume: 0.25 mg ÷ 5 mg/mL = 0.05 mL
- Units: 0.05 mL × 100 = 5 units
So you’d draw to the 5-unit mark. The same 250 mcg dose in a vial mixed with 1 mL of water instead of 2 would be 10 mg/mL, half the volume — only 2.5 units. That sensitivity to the water amount is why guessing is a bad idea and why the calculator asks for it explicitly.
Choosing your water amount
More bacteriostatic water makes a more dilute solution: larger, easier-to-read draws, but fewer doses before the vial is empty is not affected (the total peptide is the same). Less water means smaller, harder-to-measure draws. Many people choose a water volume that makes the units land on round numbers. Whatever you use, enter that same amount here — and if your compounding pharmacy specified a volume, use theirs.
Reconstituting safely
If you’re preparing a vial, the standard careful process looks like this:
- Let the vial and water reach room temperature; wipe both stoppers with a fresh alcohol swab.
- Draw the specified amount of bacteriostatic water.
- Inject the water slowly against the side of the vial — aim the stream at the glass, not directly onto the powder.
- Swirl gently to dissolve. Do not shake — agitation can damage peptides.
- Let it sit until fully clear, then store as directed.
Reconstituted peptides are generally kept refrigerated and used within the window your pharmacy specifies. Label the vial with the date and concentration so you’re never guessing later.
Important safety notes
This is where honesty matters. This calculator does math; it cannot verify what’s actually in your vial, whether the product is what it claims to be, or whether a dose is appropriate for you. A few non-negotiables:
- It does not set your dose. Use only a dose you’ve been prescribed by a licensed clinician.
- Compounded and research peptides are not FDA-approved for safety, effectiveness, or quality. Products sold “for research use only” are not intended for human use, and their actual contents and purity are not guaranteed.
- Confirm the labeled concentration with your pharmacy before drawing, and re-check your math against their instructions.
- Sterile technique matters — contamination is a real risk with self-reconstitution.
This tool is general education, not medical advice. Talk to a licensed healthcare provider before starting, changing, or acting on any peptide regimen.