Common vial sizes and water amounts
| Vial | Water | What that gives you |
|---|---|---|
| 2 mg | 1 mL | Small vials; 1 mL keeps draws readable |
| 5 mg | 1 to 2 mL | The most common combination |
| 10 mg | 2 to 3 mL | More water for larger vials |
| 30 mg | 3 to 5 mL | Large vials; a 3 mL syringe helps add water |
Worked examples
Concentration 5 mg/mL → 50 mcg per unit → draw 5 units (0.05 mL) on a 30U syringe. That vial holds about 20 such draws.
Concentration 5 mg/mL → 50 mcg per unit → draw 10 units (0.1 mL) on a 30U syringe. That vial holds about 20 such draws.
Concentration 2 mg/mL → 20 mcg per unit → draw 5 units (0.05 mL) on a 30U syringe. That vial holds about 20 such draws.
Notes for this calculator
Reconstitution means dissolving the freeze-dried powder in bacteriostatic water so it can be measured with a syringe. The powder's mass never changes; only the water you add decides how concentrated each unit is. That is why the same 250 mcg entry is 5 units in one vial and 10 units in another.
Use the "How to add the water" panel on the result card. It converts your water amount into draws on the syringe you selected, so you can add 2 mL with a 30U syringe without losing count.
Vials for this calculator: see what ThePeptideStore carries. Supplies around the vial are in the kit above.
Common questions
How do you calculate reconstitution for peptides?
Divide the vial mg by the water mL to get mg/mL. Multiply by 10 to get mcg per unit on a U-100 syringe. Divide the dose in mcg by mcg per unit to get units to draw. A 5 mg vial in 1 mL is 5 mg/mL, 50 mcg per unit, so 250 mcg is 5 units.
How much bacteriostatic water do I add to a 5 mg vial?
Any amount that fits the vial and makes your dose easy to measure. 1 mL gives 50 mcg per unit; 2 mL gives 25 mcg per unit. More water means a bigger, easier-to-read draw.
Can I use sterile water instead of bacteriostatic water?
Bacteriostatic water contains 0.9% benzyl alcohol, which is what allows a multi-dose vial to be used over many days. Plain sterile water has no preservative. The arithmetic is identical either way.
Does the calculator recommend a dose?
No. You enter the dose your protocol calls for and it converts that into syringe units, mL, and doses per vial. It never suggests what to take.
Why is my draw too big for the syringe?
The concentration is low for that dose. Either use a larger U-100 syringe or mix the next vial with less water. The calculator shows the exact water amount that would fit your syringe.