How to convert units to mg
A syringe marking measures volume. The mass in that volume depends on the concentration. On a U-100 scale:
mg = syringe units ÷ 100 × concentration in mg/mL
For U-40, replace 100 with 40. To convert the resulting milligrams to micrograms, multiply by 1,000.
Worked example: 20 units at 5 mg/mL
On a U-100 scale, 20 ÷ 100 = 0.2 mL. At 5 mg/mL, 0.2 × 5 = 1 mg, or 1,000 mcg. This is a volume-and-mass example, not a recommended amount.
U-100 units-to-mg reference at 5 mg/mL
This table applies only to the stated concentration. A different concentration changes every mass result.
| Syringe units | mL | mg | mcg |
|---|---|---|---|
| 1 | 0.01 | 0.05 | 50 |
| 5 | 0.05 | 0.25 | 250 |
| 10 | 0.1 | 0.5 | 500 |
| 20 | 0.2 | 1 | 1000 |
| 50 | 0.5 | 2.5 | 2500 |
| 100 | 1 | 5 | 5000 |
Can I convert 10 units to mg without the concentration?
No. Ten U-100 units always represents 0.1 mL, but it could contain 0.1 mg at 1 mg/mL or 0.5 mg at 5 mg/mL. Units alone do not identify the mass.
Does a 50-unit syringe use a different formula?
A 0.5 mL U-100 syringe has a 50-unit maximum capacity but still uses 100 units per mL. Use its U-100 scale, not its maximum barrel number, in this calculation.
What if I only know the vial amount?
First divide total mg by total liquid mL with the mg/mL concentration calculator. Then enter that concentration here. If your label states a final concentration, use that value.
Convert units to mL without a mass calculation or read the mg and mcg conversion guide.