Bacteriostatic Water Calculator
Peptide reconstitution & dose-to-units charts
Work out how much bacteriostatic water to add to a peptide vial and what your dose becomes in syringe units, using the reconstitution charts below — for example, 5 mg of peptide in 2 mL of water is 2.5 mg/mL. Always confirm against the product label before injecting.
How reconstitution works
Reconstituting means dissolving a freeze-dried (lyophilized) peptide with bacteriostatic water so you can measure a dose. The resulting concentration is simply the vial strength divided by the water you add — for example, 5 mg of peptide in 2 mL of water is 2.5 mg/mL.
Once you know the concentration, your dose volume is the dose divided by the concentration, and on a U-100 insulin syringe that volume × 100 gives the number of unit marks to draw. Adding more water lowers the concentration and makes each dose a larger, easier-to-measure volume.
Reconstitution chart: concentration by vial size and water added
| Vial size | +1 mL | +2 mL | +3 mL | +5 mL |
|---|---|---|---|---|
| 2 mg | 2 mg/mL | 1 mg/mL | 0.67 mg/mL | 0.4 mg/mLBest |
| 5 mg | 5 mg/mL | 2.5 mg/mL | 1.67 mg/mL | 1 mg/mL |
| 10 mg | 10 mg/mL | 5 mg/mL | 3.33 mg/mL | 2 mg/mL |
| 15 mg | 15 mg/mL | 7.5 mg/mL | 5 mg/mL | 3 mg/mL |
| 20 mg | 20 mg/mL | 10 mg/mL | 6.67 mg/mL | 4 mg/mL |
| 30 mg | 30 mg/mL | 15 mg/mL | 10 mg/mL | 6 mg/mL |
Dose to syringe units after reconstitution (by concentration)
| Dose | 1 mg/mL | 2 mg/mL | 5 mg/mL |
|---|---|---|---|
| 100 mcg (0.1 mg) | 0.1 mL → 10 | 0.05 mL → 5 | 0.02 mL → 2Best |
| 250 mcg (0.25 mg) | 0.25 mL → 25 | 0.13 mL → 13 | 0.05 mL → 5 |
| 500 mcg (0.5 mg) | 0.5 mL → 50 | 0.25 mL → 25 | 0.1 mL → 10 |
| 1 mg | 1.0 mL → 100 | 0.5 mL → 50 | 0.2 mL → 20 |
| 2 mg | 2.0 mL → 200* | 1.0 mL → 100 | 0.4 mL → 40 |
How to reconstitute a peptide vial
Storage, water type & safety
Bacteriostatic water contains benzyl alcohol as a preservative, so a reconstituted vial can be used for multiple draws; sterile water has no preservative and is single-use. Always check the product leaflet for which diluent is appropriate and how long the prepared vial stays usable.
These charts only handle reconstitution math — they do not decide whether a product should be reconstituted or whether a dose is right for you. Keep the prepared vial refrigerated and labeled with its concentration and date, follow your prescriber’s or the product’s instructions, and ask your pharmacist when in doubt.
Frequently Asked Questions
It depends on the concentration you want. 5 mg in 1 mL gives 5 mg/mL; in 2 mL gives 2.5 mg/mL; in 5 mL gives 1 mg/mL. More water means a larger, easier-to-measure injection volume. Use the reconstitution chart above to choose.
10 mg in 1 mL is 10 mg/mL; in 2 mL is 5 mg/mL; in 5 mL is 2 mg/mL. Pick the concentration that makes your typical dose a convenient number of syringe units.
Bacteriostatic water contains benzyl alcohol as a preservative, so a vial can be used for multiple draws; sterile water has none and is single-use. Follow the product leaflet for which to use.
Divide the dose by the concentration to get the volume in mL, then multiply by 100 for U-100 units. Example: a 250 mcg dose from a 2 mg/mL vial is about 0.125 mL, or roughly 13 units.
Yes. Shotlee stores your vial concentration, dose logs, side effects, and reminders so you do not have to recompute every time.
Save Your Reconstitution Plan in Shotlee
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📚References & sources
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