How do I read the unit marks on an insulin syringe?
First check the scale printed on the syringe or packaging (U-100 is the most common). The barrel number is units of volume: on U-100, each unit is 0.01 mL. Check the size too: a 0.3 mL U-100 syringe holds 30 units, 0.5 mL holds 50 and 1 mL holds 100. Smaller barrels usually mark every unit; 1 mL barrels often mark every 2 units, so each small line can be 2 units. Read where the top edge of the plunger seal meets the line. Count the lines between two numbers to find what each line is worth.
The math
value per line = (difference between two numbered marks) ÷ (lines between them) mL = units ÷ 100 (U-100) capacity (units) = syringe mL × 100 (U-100)
| Syringe size | U-100 capacity | U-50 capacity | U-40 capacity |
|---|---|---|---|
| 0.3 mL | 30 units | 15 units | 12 units |
| 0.5 mL | 50 units | 25 units | 20 units |
| 1 mL | 100 units | 50 units | 40 units |
Math only, not medical advice. This page converts numbers; it does not recommend any compound or amount.
Draw to
10 units
= 0.1 mL · concentration 2.5 mg/mL (2500 mcg/mL) · 20 draws per vial
Concentration = 5 mg ÷ 2 mL = 2.5 mg/mL Volume = 250 mcg ÷ 2500 mcg/mL = 0.1 mL Units = 0.1 mL × 100 (U-100) = 10 units
Math only, not medical advice. Verify every number yourself.