mg to Units Calculator
Milligrams cannot be converted to syringe units without knowing the concentration, because units measure volume rather than mass. Divide the dose in milligrams by the concentration in mg/mL to get millilitres, then multiply by 100 for a U-100 syringe.
The formula
units = (mg ÷ mg per mL) × 100
On a U-100 insulin syringe, 100 units is 1 mL and 1 unit is 0.01 mL. The conversion from milligrams therefore always passes through volume, which is why the concentration is required.
Calculate your dose
Enter your vial and dose to see the units to draw.
10units on a U-100 syringe
- Concentration
- 2.5 mg/mL
- Volume to draw
- 0.1 mL
- Per unit
- 25 mcg
- Doses per vial
- 20
Worked examples
Milligram-to-unit conversions at four common concentrations.
2.5 mg/mL concentration
10units
- Concentration
- 2.5 mg/mL
- Dose
- 0.25 mg
- Volume
- 0.1 mL
5 mg/mL concentration
10units
- Concentration
- 5 mg/mL
- Dose
- 0.5 mg
- Volume
- 0.1 mL
10 mg/mL concentration
10units
- Concentration
- 10 mg/mL
- Dose
- 1 mg
- Volume
- 0.1 mL
1 mg/mL concentration
50units
- Concentration
- 1 mg/mL
- Dose
- 0.5 mg
- Volume
- 0.5 mL
Frequently asked questions
- How many units is 1 mg?
- There is no single answer without a concentration. At 1 mg/mL, 1 mg is 100 units. At 5 mg/mL it is 20 units, and at 10 mg/mL it is 10 units.
- Are units the same as milligrams?
- No. Units are a volume marking on the syringe barrel — 100 units equals 1 mL on a U-100 syringe. The mass in milligrams that a unit represents depends entirely on your concentration.
- How do I convert units back to mg?
- Divide the units by 100 to get millilitres, then multiply by the concentration in mg/mL. For example, 20 units at 5 mg/mL is 0.2 mL, which is 1 mg.
- What is mcg per unit?
- Multiply the concentration in mg/mL by 1000 to get mcg/mL, then divide by 100 for a U-100 syringe. At 2.5 mg/mL, each unit contains 25 mcg.
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