GLP1 MathHow to read a U-100 insulin syringe
A U-100 insulin syringe is marked in units. On these syringes, 100 units always equals 1 mL, so one unit is 0.01 mL. The common sizes are 0.3 mL (30 units), 0.5 mL (50 units) and 1 mL (100 units). Smaller syringes have finer markings and are easier to read for small doses.
Units measure liquid, not medicine
The units tell you how much liquid you are drawing. How much medicine is in that liquid depends on the vial strength, written as mg per mL. That is why your pharmacy label matters more than any chart you find online.
The two-step math
First, mL = your dose in mg ÷ the vial strength in mg/mL. Second, units = mL × 100. Example: a 1 mg dose from a 5 mg/mL vial is 0.2 mL, which is 20 units.
Read at eye level
Hold the syringe at eye level and read the line at the flat top of the plunger. Tap out air bubbles before you confirm the reading, since bubbles take up space that should be medicine.