Insulin syringe units, explained
The lines on an insulin syringe measure liquid, not peptide. On a U-100 syringe, 100 units equals 1 mL. How much peptide is in those units depends on how much water you mixed in.
The one rule
100 units = 1 mL · 1 unit = 0.01 mL
That's true for every U-100 insulin syringe, whatever its size. The 0.3 mL, 0.5 mL and 1 mL versions just hold 30, 50 or 100 units.
Units vs mL vs mg
To turn a dose into units: units = dose (mg) ÷ (vial mg ÷ water mL) × 100.
Which syringe size to use
| Syringe | Holds | Each small line | Best for |
|---|---|---|---|
| 0.3 mL | 30 units | 1 unit (some have half units) | Small doses where precision matters |
| 0.5 mL | 50 units | 1 unit | Most daily peptide doses |
| 1 mL | 100 units | 2 units | Larger doses |
The smaller the syringe, the easier it is to read a small dose accurately.
Try it
Common questions
Is 10 units the same as 10 mg?
No. Units are volume, so 10 units is 0.1 mL. How many mg that holds depends on how strong your mix is.
Can I use a U-40 syringe?
Don't. U-40 syringes are marked differently, and every peptide chart and calculator assumes U-100.
How do I read half units?
Some 0.3 mL syringes have half-unit marks. Otherwise, add more water when you mix so your dose lands on a whole number.