Insulin Syringe Units Explained: Reading 30, 50, and 100-Unit Syringes
"Units" is the most confusing word in peptide tracking, because it sounds like an amount of compound. It isn't. On a standard U-100 insulin syringe, a unit is a volume: 1/100th of a milliliter. This guide covers how to read the three common syringe sizes and convert between mL and units.
Note: this article explains how syringe markings work. It does not recommend doses or protocols.
The one conversion you need
units = mL × 100 mL = units ÷ 100
| Volume | U-100 units |
|---|---|
| 0.05 mL | 5 units |
| 0.1 mL | 10 units |
| 0.25 mL | 25 units |
| 0.5 mL | 50 units |
| 1.0 mL | 100 units |
The three common sizes
| Syringe | Total volume | Typical marking |
|---|---|---|
| 30-unit (0.3 mL) | 0.3 mL | Every 1 unit (some ½ unit) |
| 50-unit (0.5 mL) | 0.5 mL | Every 1 unit |
| 100-unit (1 mL) | 1.0 mL | Every 2 units |
All three use the same unit scale: 10 units is 0.1 mL on every one of them. Smaller barrels spread the same volume over more physical length, so small draws are easier to read precisely on a 30-unit syringe than on a 100-unit syringe, where each tick is 2 units.
Common mistakes
- Reading a 100-unit syringe as if every tick is 1 unit. On most 1 mL syringes each small line is 2 units.
- Assuming the same units means the same amount. 10 units of a 2.5 mg/mL solution and 10 units of a 5 mg/mL solution contain different amounts. Units depend on how you reconstituted the vial (see our reconstitution math guide).
- Mixing up U-100 and U-40 syringes. U-40 syringes (used in veterinary settings) have a different scale entirely. Everything here assumes U-100.
See the fill line instead of counting ticks
PepMinder (free on Android) converts your amount to units and draws a visual syringe diagram for your syringe size (30, 50, or 100 unit), with the fill line marked. No tick counting, no mental math.
Try PepMinder free on Android
Reconstitution calculator, dose reminders, and an injection log in one private app. No account, works offline.
Get it on Google PlayPepMinder is a personal tracking and calculation tool. It does not provide medical advice, diagnosis, dosing recommendations, or protocols, and it does not sell or link to any products. Always consult a licensed healthcare provider about your treatment.