U-100 Syringe Units Explained: How Many Units to Draw
Published: 2026-08-29 · PeptApp
The single most common point of confusion in peptide tracking: the numbers on an insulin syringe are not a dose. They are a volume. Once that clicks, every conversion becomes three small steps.
Units measure volume, not peptide
U-100 means 100 units per millilitre. One unit is 0.01 ml of liquid — nothing more. How much peptide is in that unit depends entirely on the concentration you created at reconstitution. The same “10 units” holds twice the peptide in a 5 mg/ml vial as in a 2.5 mg/ml vial.
The three-step conversion
To find how many units to draw:
- mcg → mg: divide by 1000.
- mg → ml: divide by the vial’s concentration in mg/ml.
- ml → units: multiply by 100 (on a U-100 syringe).
A quick chart at 2.5 mg/ml
| Dose | Volume | U-100 units |
|---|---|---|
| 100 mcg | 0.04 ml | 4 |
| 250 mcg | 0.10 ml | 10 |
| 500 mcg | 0.20 ml | 20 |
| 1 mg | 0.40 ml | 40 |
The chart only holds at 2.5 mg/ml — change the reconstitution volume and every row changes. That is why a chart can never replace redoing the math for your vial.
Watch out for U-40 syringes
Veterinary and some imported syringes are U-40: 40 units per ml, so one unit is 0.025 ml — two and a half times more liquid than a U-100 unit. Drawing a U-100 number on a U-40 syringe over-doses by 150%. Always check the barrel before trusting any unit figure.
Make it automatic
Doing this chain by hand twice a day invites mistakes. PeptApp stores each vial’s concentration and syringe type, converts every scheduled dose to draw units automatically, and shows the number right on the reminder.
Let the app do this math
PeptApp calculates reconstitution and syringe units, schedules every dose, tracks vial expiry and reminds you to inspect — all on your device, nothing in the cloud.
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