How the TB-500 concentration calculation works
Concentration is the entered vial amount divided by the resulting solution volume. In this arithmetic example, 5 mg in 2 mL is 2.5 mg/mL. On a U-100 insulin syringe one unit represents 0.01 mL, so this example has 25 mcg per unit. An entered amount of 2.5 mg therefore corresponds to 100 units.
The tables illustrate conversions, not a treatment schedule. They cannot determine whether a product is approved or suitable for human use. Follow product-specific instructions from your qualified prescriber or pharmacist for preparation, dose, device, and storage.
TB-500 conversion examples (5 mg in 2 mL)
| Dose | Units | mL | Doses per vial |
|---|---|---|---|
| 2 mg | 80 | 0.8 | 2 |
| 2.5 mg | 100 | 1 | 2 |
| 5 mg | 200 | 2 | 1 |
Example amounts at 2.5 mg per dose
| Vial | Water | Concentration | Units per dose | Doses |
|---|---|---|---|---|
| 2 mg | 2 mL | 1 mg/mL | 250 | 0 |
| 5 mg | 2 mL | 2.5 mg/mL | 100 | 2 |
| 10 mg | 2 mL | 5 mg/mL | 50 | 4 |
Each amount shows its unit; the form starts in mg. For a fixed amount and dose, doubling the resulting solution volume halves the concentration and doubles the calculated units. The arithmetic number of doses is unchanged. This relationship does not establish an appropriate preparation volume or syringe for a product.
Worked example
5 mg / 2 mL = 2.5 mg/mL = 2,500 mcg/mL. One unit = 0.01 mL = 25 mcg. 2,500 mcg / 25 mcg per unit = 100 units. The vial holds 5,000 / 2,500 = 2 doses, which at 2 per week is about 7 days.
See the general peptide reconstitution calculator for the formulas and mg-to-mcg conversions, and our calculator methodology and limitations. The FDA's report on compounded semaglutide dosing errors explains why concentration, units, and measurement instructions need to be confirmed with a health care provider or compounder.