How do I convert mg or mcg into units on a U-100 syringe?
Updated: 2026-09-09 · Reconstitution and syringes
Short answer
Units = (the mg you want ÷ your vial's concentration in mg/ml) × 100, because a U-100 syringe holds 100 units in 1 ml and each unit is 0.01 ml. So you first work out the concentration (vial mg ÷ ml of water), then apply that division. And remember 1 mg = 1000 mcg — that is the most common slip.
In plain English
- 1 ml = 100 units. 0.1 ml = 10 units.
- U-100 'units' are syringe volume graduations (100 marks per ml), not universal dose units for any peptide or drug.
- 1 mg = 1000 mcg — the most common 1000x error.
- Concentration = vial mg ÷ ml of water.
- Units = (desired mg ÷ concentration) × 100.
What we know
- Arithmetic example: a 10 mg vial with 2 ml is 5 mg/ml; drawing 0.5 mg equals 0.1 ml, or 10 units.
- The site calculator runs these steps with your vial's real concentration.
What we don't know yet
- How many milligrams suit a specific person — this page does not calculate doses.
The example is conversion arithmetic, not a recommended dose.