Insulin syringe units to mL
For U-100 insulin, 100 units = 1 mL, so 1 unit = 0.01 mL. Divide units by 100 to get mL. 10 units = 0.1 mL; 50 units = 0.5 mL.
Units to mL chart
| Units | mL |
|---|---|
| 1 units | 0.01 |
| 2 units | 0.02 |
| 5 units | 0.05 |
| 10 units | 0.1 |
| 15 units | 0.15 |
| 20 units | 0.2 |
| 25 units | 0.25 |
| 30 units | 0.3 |
| 40 units | 0.4 |
| 50 units | 0.5 |
| 75 units | 0.75 |
| 100 units | 1 |
How to read an insulin syringe
Every U-100 syringe is marked in units, not mL. The barrel size decides how far apart the lines are:
| Barrel | Holds | Small lines | Numbers every |
|---|---|---|---|
| 0.3 mL | 30 units | 1 unit (half units on some brands) | 5 units |
| 0.5 mL | 50 units | 1 unit | 5 units |
| 1 mL | 100 units | 2 units | 10 units |
- Check the syringe says U-100 and matches your insulin's concentration.
- Count the lines: on a 0.3 or 0.5 mL syringe each small line is 1 unit; on a 1 mL syringe each is 2 units.
- Read the dose at the top edge of the black stopper (the edge nearest the needle), not the bottom or the plunger rod.
- Tap out air bubbles before you read. A bubble takes up space, so you'd get less insulin than the line shows.
The formula
mL = units ÷ 100 units = mL × 100 example: 15 units → 15 ÷ 100 = 0.15 mL
The same rule holds for any liquid drawn into a U-100 syringe, which is why insulin syringes are used for other injectables too. For a medicine measured in mg, use the mg to units calculator, which adds the concentration step.
Pick the smallest syringe that fits
Doses up to 30 units are easiest to measure in a 0.3 mL syringe, up to 50 units in a 0.5 mL syringe, and up to 100 units in a 1 mL syringe. Smaller barrels spread the same dose over more distance, so each unit is easier to see. If you switch syringe size, check where your usual dose falls on the new one before injecting.
Questions
How many mL is 10 units of insulin?
0.1 mL, for U-100 insulin.
How many units is 0.5 mL?
50 units on a U-100 syringe. That fills a 0.5 mL syringe to the top line.
How do I read a 0.5 mL insulin syringe?
A 0.5 mL syringe holds 50 units. Each small line is 1 unit and the numbered lines are every 5 units. Read the dose at the top edge of the plunger's black stopper, the edge nearest the needle.
What do the lines on a 1 mL insulin syringe mean?
A 1 mL syringe holds 100 units. Each small line is 2 units and the numbers are every 10 units, so odd doses like 25 units fall between lines. Use a 0.5 mL syringe for those if you can.
Can I use a U-100 syringe for U-500 insulin?
No. Concentrated insulin (U-200, U-300, U-500) must not be drawn with a U-100 syringe unless your prescriber gives exact instructions. Humulin R U-500 vials are used with dedicated U-500 syringes.