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Results
Same amount, different liquid volumes
Adding more liquid dilutes the vial, so you draw more units for the same amount. A larger volume is easier to measure accurately; a smaller one fits a smaller syringe.
| Liquid added | Concentration | Units to draw | Uses per vial |
|---|
Units → amount
Already mixed? Enter the units on your syringe to see how much peptide that is at the concentration above.
How the math works
- Concentration = peptide in vial ÷ liquid added. 5 mg in 2 mL = 2.5 mg/mL (2,500 mcg/mL).
- Volume to draw = amount wanted ÷ concentration. 250 mcg ÷ 2,500 mcg/mL = 0.1 mL.
- Units (U-100) = volume in mL × 100. 0.1 mL = 10 units.
- Uses per vial = total peptide ÷ amount per use. 5,000 mcg ÷ 250 mcg = 20.
Real-world yield is a little lower than the calculated figure because some liquid stays in the vial and in the syringe.
Frequently asked questions
How do you calculate peptide concentration after reconstitution?
Divide the amount of peptide in the vial by the volume of liquid you add. A 5 mg vial mixed with 2 mL gives 2.5 mg/mL, which is 2,500 mcg per mL. Concentration is simply peptide amount divided by liquid volume.
What does a unit on an insulin syringe mean?
A U-100 insulin syringe is marked so that 100 units equal 1 mL, so 1 unit is 0.01 mL. Units are a measure of volume, not of the peptide itself. How much peptide a unit contains depends entirely on the concentration of your mixed vial.
Why does the amount of water change the number of units?
The peptide amount in the vial is fixed. Adding more liquid dilutes it, so each unit contains less peptide and you draw more units for the same dose. Adding less liquid concentrates it, so a smaller volume carries the same dose.
What is a sensible amount of liquid to add?
That is a practical choice rather than a safety rule: enough that the volume you measure is not so tiny that a small reading error becomes a large dose error, and not so large it exceeds your syringe. The comparison table on this page shows how the same dose reads at different volumes.
How many doses are in a vial?
Total peptide in the vial divided by the dose per use. A 5 mg (5,000 mcg) vial at 250 mcg per dose yields 20 doses. Real-world yield is slightly lower because some liquid stays in the vial and syringe dead space.
Is this calculator medical advice?
No. It only does arithmetic on the numbers you enter. It does not know what any peptide is, what a suitable amount might be, or whether your numbers are correct. Always double-check results independently and talk to a qualified clinician or pharmacist.