How-to · 3 min read
Reading an insulin syringe
Units, ml, and why the tick marks matter.
Peptide doses are drawn with U-100 insulin syringes. “U-100” means the barrel is marked so that 100 units = 1ml. The units are just volume markings — they say nothing about the drug inside. What a unit is “worth” depends on how you mixed the vial.
Three common sizes
| Syringe | Holds | Marks | Best for |
|---|---|---|---|
| 0.3ml | 30 units | often half-units | Small, precise doses |
| 0.5ml | 50 units | 1 unit | Everyday use |
| 1ml | 100 units | 2 units | Larger doses |
Turning a dose into units
Units = dose ÷ strength × 100. With a 10mg vial in 2ml (5mg/ml), a 0.25mg dose is 0.05ml — 5 units. The calculator does this for you.
Tips
- Read the mark at the top edge of the plunger’s rubber, not the tip of the cone.
- Tap out air bubbles and push them back before reading.
- If a dose works out to more than the syringe holds, mix with less water or use a bigger vial.