Get the units right, the first time.
For prescribed, clinician-supervised peptides. Enter your vial, your water, and the dose your provider set — the calculator shows the exact draw, and the math behind it. For tracking & education only; it never recommends a dose.
Lumara is a tracking tool and does not provide medical advice, diagnosis, or treatment. This calculator computes the math from the numbers you enter; it never recommends a dose. Always follow your provider's guidance.
How to reconstitute a peptide, step by step
Reconstitution is dissolving a freeze-dried (lyophilised) peptide in bacteriostatic water so it can be drawn into a syringe. The calculator does the arithmetic; the method below is the physical process it assumes.
- Sanitise. Wipe both the peptide vial stopper and the BAC-water vial with an alcohol swab and let them dry.
- Add the water slowly. Draw your chosen volume of bacteriostatic water and let it run down the inside wall of the vial — never inject it straight onto the powder.
- Swirl, don’t shake. Gently roll the vial until the powder fully dissolves. Shaking can damage fragile peptides.
- Let it settle, then read the units to draw from the calculator and store the vial per your label’s beyond-use date.
Worked example: a 10 mg vial at a 250 mcg dose
Say your provider prescribed 250 mcg and you have a 10 mg vial you plan to reconstitute with 2 mL of BAC water:
- Concentration — 10 mg ÷ 2 mL = 5 mg/mL (5000 mcg/mL).
- Volume for your dose — 250 mcg ÷ 5000 mcg/mL = 0.05 mL.
- Units to draw — 0.05 mL × 100 units/mL = 5 units on a U-100 insulin syringe.
- Doses per vial — 10 mg ÷ 0.25 mg = 40 doses.
Enter your own numbers above to see your figures — including the reverse mode, which solves the water volume that lands your dose on a clean syringe mark.
Sources
- U.S. Food and Drug Administration. FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products. July 26, 2024.
- Hospira, Inc. Bacteriostatic Water for Injection, USP (benzyl alcohol–preserved, multiple-dose vial). Drug label, NDA 018802 (revised 08/2019). DailyMed, U.S. National Library of Medicine.
Frequently asked questions
There is no single right amount — the water only sets the concentration, not the dose. More water makes each unit on the syringe less concentrated (easier to measure small doses precisely); less water makes it more concentrated. Enter your vial strength and the water you plan to add and the calculator shows the exact units your prescribed dose becomes. A common choice is 2 mL of BAC water for a 10 mg vial, giving 5 mg/mL.
Concentration (vial strength ÷ water volume), the volume your dose occupies, and that volume expressed in insulin-syringe units on a U-100 (100 units = 1 mL) scale. It also estimates doses per vial and roughly how long the vial lasts, and shows the full derivation — it never recommends a dose.
A 250 mcg (0.25 mg) dose of a 5 mg/mL solution is 0.05 mL, which is 5 units on a U-100 insulin syringe. That 10 mg vial yields 40 such doses.
Once mixed, most reconstituted peptides are kept refrigerated and used within a beyond-use window set by the compounder or your provider (commonly a few weeks). The calculator estimates depletion from your dose and frequency, but always follow the discard-by date on your label and your provider’s guidance.
No. It is an educational estimation tool. It does the arithmetic from the numbers you enter and shows its work; it never prescribes, diagnoses, or recommends a dose. Always follow the instructions from your licensed provider.