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Insulin syringe units to mL: the quick conversion
100 units is 1 mL, so units ÷ 100 = mL. The conversion table, why a unit says nothing about what's in the vial, and the U-40 trap.
Last reviewed · written by PepPrep · not medical advice
On every standard U-100 insulin syringe, 100 units is 1 mL. That is the only fact you need, and everything else on this page is that fact rearranged.
| Units | mL | Units | mL |
|---|---|---|---|
| 1 | 0.01 | 30 | 0.30 |
| 2 | 0.02 | 40 | 0.40 |
| 5 | 0.05 | 50 | 0.50 |
| 10 | 0.10 | 60 | 0.60 |
| 15 | 0.15 | 75 | 0.75 |
| 20 | 0.20 | 100 | 1.00 |
| 25 | 0.25 |
To convert either way: units ÷ 100 = mL, and mL × 100 = units. So 0.35 mL is 35 units; 12 units is 0.12 mL.
"Units" are not a measure of anything in the vial
This is where people get lost. A unit on the syringe is a hundredth of a millilitre of liquid. It says nothing about how much of anything is dissolved in that liquid — that depends entirely on how much water went into the vial. Two vials mixed with different amounts of water give you different amounts per unit. The syringe cannot know that; only your label can. The reconstitution calculator does that arithmetic for you from the vial size and the water you added.
U-40 syringes exist and are a trap
Veterinary insulin syringes are marked U-40: 40 units to the millilitre, so every line is worth two and a half times more liquid. They look almost identical. Check the barrel says U-100 before you buy a box, especially outside the US, where U-40 pet syringes show up in the same search results. The full units table has every marking on all three barrel sizes; the reading guide shows where to look on the barrel.
Supplies mentioned: Syringes & Needles