Tools
Reconstitution calculator
Enter the vial and the amount you want per draw. It tells you how much bacteriostatic water to add and where that lands on the syringe, so the draw sits on a tick mark.
Reconstitution calculator
Pick the vial and the amount you want per draw. It works out the water to add and where that lands on the syringe.
In micrograms. 1 mg is 1,000 mcg.
Syringe
Add to the vial
2.4 mL bacteriostatic water
Draw
1 units for 250 mcg
- Concentration
- 25 mg/mL
- Per unit
- 250 mcg
- Draws per vial
- 240
- Under 2 units is hard to measure. Add more water so each draw is larger.
How the maths works
Everything comes from one relationship: the peptide mass divided by the water you add is the concentration.
Concentration
mg/mL = peptide (mg) ÷ water (mL)
Units to draw
units = amount (mg) ÷ concentration (mg/mL) × 100
On a U-100 insulin syringe, 100 units is 1 mL, so one unit is 0.01 mL.
Rather than asking how much water you plan to add, the calculator starts from what you know, the vial and the amount per draw, and picks a water volume that puts the draw on a whole unit. Tick the override to try your own volume.
Common set-ups
A 250 mcg draw from the four most common vial and water combinations.
| Vial | Water | Concentration | 250 mcg draw |
|---|---|---|---|
| 10 mg | 2.0 mL | 5 mg/mL | 5 units |
| 10 mg | 1.0 mL | 10 mg/mL | 2.5 units |
| 5 mg | 2.0 mL | 2.5 mg/mL | 10 units |
| 5 mg | 1.0 mL | 5 mg/mL | 5 units |
- Draws between 5 and 20 units are the easiest to read. Below 2 units, add more water. Above the syringe capacity, use less.
- Use bacteriostatic water, not plain sterile water, for any vial you will draw from more than once.
- Label the vial with the date and the concentration. The copy button writes that line for you.
For in-vitro laboratory research only. Not for human or veterinary use. See the catalogue for bacteriostatic water and syringes.