Insulin syringes, decoded

U-100

U-100 means 100 units of insulin per mL. Peptide users borrow the barrel as a volume ruler: 100 units = 1.00 mL, 10 units = 0.10 mL, 1 unit = 0.01 mL.

The unit tick is volume. Micrograms depend on how concentrated you mixed the vial. That is why Mix asks for milligrams and water first.

Pick a barrel that fits

0.3 mL syringes (30 units) are accurate for tiny doses. If the calculator says 40 units, you need a 0.5 mL or 1 mL barrel — or more water in the vial, which makes each unit fewer mcg.