The formula
The water volume is the vial mass divided by the concentration you want: water (mL) = vial size (mg) ÷ target concentration (mg/mL). A 5 mg vial at 2.5 mg/mL needs 2 mL; the same vial at 1 mg/mL needs 5 mL. If you think in mcg per 0.1 mL instead, multiply that figure by 10 to get mcg per mL first.
The third mode starts from a syringe reading. If you want a given amount to read as a given number of units, the concentration must be the amount divided by the volume those units represent (units ÷ 100 on U-100, units ÷ 40 on U-40). The calculator then divides the vial mass by that concentration.
Choosing a volume you can measure
Less water gives a stronger solution and smaller draws that are harder to read accurately. More water gives larger, easier readings but needs a vial with room for it. Most research vials hold 3 to 10 mL. Check your result in the reconstitution calculator and read how to reconstitute peptides and bacteriostatic water vs sterile water before you start.
Frequently asked questions
How much BAC water should I add to a 5 mg vial?
It depends on the concentration you want. Water volume = vial mass ÷ target concentration. For 2.5 mg/mL, a 5 mg vial needs 5 ÷ 2.5 = 2 mL. For 1 mg/mL it needs 5 mL.
Does adding more water change the amount of peptide?
No. Water only changes the concentration. The total peptide in the vial stays the same, so a larger volume simply means each 0.1 mL holds less.
What is the formula for BAC water volume?
Water (mL) = vial size (mg) × 1,000 ÷ target concentration (mcg/mL). If you target a syringe reading instead, the concentration is the amount divided by (units ÷ units per mL).
Is this calculator medical advice?
No. It is unit arithmetic for laboratory handling only and does not recommend any amount of any compound.
More free tools
- Peptide reconstitution calculator (U-100 and U-40)
- BAC water calculator
- Peptide unit converter (mg, mcg, IU, mL and units)
- COA checklist
- Vendor testing tracker
Choosing a supplier? See the best peptide vendors in the USA.