Syringe sizes explained: 0.3 mL, 0.5 mL and 1 mL

Insulin syringes used for peptides are U-100: 100 units is 1 mL, whatever the size of the syringe. They come in three common sizes: 0.3 mL (30 units), 0.5 mL (50 units) and 1 mL (100 units).

A dose is the same number of units on all three. Smaller syringes just have their lines closer together, so they’re easier to read.

Lines every 2 units. It holds the biggest doses, but a dose on an odd number of units sits halfway between two lines, which makes small doses hard to read.

Lines every unit. A good fit for most doses up to 50 units.

Lines every unit, and on some brands every half unit. The calculator always rounds to whole units to be safe. The easiest to read for small doses.

Use the smallest syringe that holds your whole dose in one draw: up to 30 units, 0.3 mL; up to 50 units, 0.5 mL; above that, 1 mL.

If a dose is more than 100 units, don’t split it into two draws. Recheck your numbers: it usually means the vial was mixed with more water than the dose needs.