Reconstitution calculator
Enter what you know and the tool works out the rest — the draw on the syringe, the concentration, and how many doses the vial holds.
Total peptide in the vial, as printed on the label.
Bacteriostatic water or solvent added to the vial.
The amount you want in a single draw.
Units on the 0.5mL U-100 insulin syringe we ship — 50 units full.
How the calculation works
Reconstitution is a dilution problem, and it only ever has two moving parts: how much peptide is in the vial, and how much liquid you put in with it. Everything else follows.
- Concentration
- Vial strength ÷ water added. A 10mg vial with 2mL of water is 5mg/mL. The vial holds the same 10mg however much water goes in — more water simply spreads it thinner.
- Draw volume
- Target dose ÷ concentration. At 5mg/mL, 2.5mg occupies 0.5mL. This is why a larger volume of water means a larger draw for the same amount of peptide.
- Units on the syringe
- Draw volume × 100. U-100 marking means 100 units to 1mL, so 0.5mL is the 50-unit line. The syringes we ship are 0.5mL — a full barrel — which is why the tool flags a draw above 50 units. A different barrel size uses the same marking; only the capacity changes.
- Doses per vial
- Vial strength ÷ target dose, independent of how much water was added. Water changes the volume of each draw, never the number of them.
Storage and handling guidance for each compound is on its own product page, underStorage andReconstitution.Browse the catalog →
Common questions
What is bacteriostatic (BAC) water and do I need it?
BAC water is sterile water containing a small amount of benzyl alcohol, used to dissolve lyophilised peptide powder before use. Some compounds instead use acetic acid as the reconstitution solvent — check the specific product page for which one applies. Both are referenced in our Reconstitution Instructions and Calculator.
How do I know how much water to add or dose to draw?
Use our free Reconstitution Calculator — enter any two of vial strength, water added, or target dose, and it works out the rest, including the draw line on a standard insulin syringe.
How long does a reconstituted vial last?
This varies by compound — see the Storage Instructions section on the specific product page.
How do I use this calculator?
Enter any two of vial strength, water added, and target dose; we calculate the third, plus the draw line on a standard insulin syringe.
What syringe does the draw line assume?
The 0.5mL U-100 insulin syringe we ship — 50 units fills the barrel. U-100 means 100 units to 1mL, so the markings are the same on a larger barrel; only the capacity differs. Using another size? Use the mg/mL concentration figure directly.
How is concentration calculated?
Total peptide in the vial ÷ water added. A 5mg vial with 2mL water = 2.5mg/mL.
Why does more water mean a bigger draw volume for the same dose?
More water dilutes the peptide, lowering concentration — so a larger volume is needed to reach the same target amount.
Is this a substitute for professional guidance?
No. This tool estimates reconstitution math for research reference only; it does not replace an institution's own research protocols.