U-100 conversion table
| Units (U) | mL |
|---|---|
| 1 | 0.01 |
| 5 | 0.05 |
| 10 | 0.10 |
| 20 | 0.20 |
| 25 | 0.25 |
| 30 | 0.30 |
| 50 | 0.50 |
| 100 | 1.00 |
How much active substance is in one unit?
That depends on how concentrated the solution is:
Concentration (mg/mL) = active substance in the vial (mg) ÷ liquid (mL)
Volume (mL) = desired amount (mg) ÷ concentration
Units = volume × 100
Example: 5 mg dissolved in 2 mL gives 2.5 mg/mL. An amount of 0.25 mg then corresponds to 0.1 mL – i.e. 10 units. Our reconstitution calculator does this automatically, including a syringe graphic.
The most common mistakes
- Wrong syringe type: There are also U-40 syringes (e.g. from veterinary medicine), where 40 units are 1 mL. Always look for “U-100”.
- Mixing up mg and mcg: 1 mg = 1,000 mcg. A typo immediately means ten or a thousand times the amount.
- Misreading the scale: 0.3 mL syringes often have marks in steps of 1, 1 mL syringes in steps of 2.
- Assuming pen clicks are units: On some pens one click is 0.01 mL, on others it is not – always check the instructions.
When to see a doctor
- You are unsure whether you have converted correctly – better to have it double-checked at a pharmacy
- Unusually strong side effects occur after an injection
In an emergency: 112.
FAQ
How many mL are 10 units on an insulin syringe?
On a U-100 syringe, 10 units are 0.1 mL.
How many units are in 1 mL?
On U-100 syringes, 100 units.
Are units on the syringe the same as units of active substance?
No. On the syringe, a unit is a measure of volume (0.01 mL). How much active substance it contains depends on the concentration of the solution.
Are “IU” in a calculator the same as units on the syringe?
Usually yes: many peptide calculators say “IU” but mean the marks on the U-100 syringe (0.01 mL). Real international units are a measure of potency, e.g. for insulin or growth hormone – that is something different.
Is one click on the pen one unit?
On many reusable pens, one click equals 0.01 mL, i.e. one unit on the U-100 syringe. But this is not true for every pen – always check the instructions.
This article does not replace medical advice. It gives no dosing recommendations. As of September 2026.