Syringe units, mL and mcg
A unit is a volume, not an amount. What it holds depends on the vial.
Insulin syringes are marked in units. On the U-100 scale used by nearly all insulin syringes sold today, 100 units is exactly 1 mL, so each unit is 0.01 mL. That relationship is fixed. What changes is how many micrograms sit in each 0.01 mL, and that is set by the vial: the mass of peptide in it divided by the liquid added.
The converter below goes both ways: a syringe reading to mL and mass, or a mass to the reading it would occupy, at whatever concentration is entered.
Units converter
Set the vial and water first; both conversions use the resulting concentration.
Units to mL and amount
0.1 mL = 250 mcg
Amount to units
10 units = 0.1 mL
U-100 units to mL, and what they hold at three concentrations
| Units | mL | 5 mg in 2 mL | 10 mg in 2 mL | 10 mg in 1 mL |
|---|---|---|---|---|
| 1 | 0.01 | 25 mcg | 50 mcg | 100 mcg |
| 2 | 0.02 | 50 mcg | 100 mcg | 200 mcg |
| 5 | 0.05 | 125 mcg | 250 mcg | 500 mcg |
| 10 | 0.1 | 250 mcg | 500 mcg | 1 mg |
| 15 | 0.15 | 375 mcg | 750 mcg | 1.5 mg |
| 20 | 0.2 | 500 mcg | 1 mg | 2 mg |
| 25 | 0.25 | 625 mcg | 1.25 mg | 2.5 mg |
| 30 | 0.3 | 750 mcg | 1.5 mg | 3 mg |
| 40 | 0.4 | 1 mg | 2 mg | 4 mg |
| 50 | 0.5 | 1.25 mg | 2.5 mg | 5 mg |
| 75 | 0.75 | 1.875 mg | 3.75 mg | 7.5 mg |
| 100 | 1 | 2.5 mg | 5 mg | 10 mg |
Reading the scale
A 1 mL U-100 syringe usually has a mark every 2 units and a number every 10. Half-mL and 0.3 mL barrels usually mark every unit, and some 0.3 mL barrels mark half units. A result such as 7.5 units falls between marks on a 1 mL barrel but on a mark on a finer one, which is why the calculators let the barrel size be selected.
The math in both directions is the same pair of steps: mL = units / 100, and mass = mL x concentration. The vial calculator runs it from the vial side, and each peptide page applies it to that peptide's usual vial sizes.
Syringe unit questions
How many mL is 10 units on an insulin syringe?
On a U-100 syringe, 10 units is 0.1 mL. Every unit is 0.01 mL, so 50 units is 0.5 mL and 100 units is 1 mL.
How many mcg is 10 units?
It depends on the concentration. At 2,500 mcg/mL (5 mg in 2 mL), 10 units holds 250 mcg. At 5,000 mcg/mL (10 mg in 2 mL), the same 10 units holds 500 mcg.
Are 0.3 mL, 0.5 mL and 1 mL syringes read differently?
Not if they are all U-100. The marks are the same volume on each; a smaller barrel just ends sooner, at 30, 50 or 100 units. Smaller barrels usually have finer gradations, which makes small volumes easier to read.
What is a U-40 syringe?
U-40 syringes are made for U-40 insulin, mostly in veterinary use. On them 40 units is 1 mL, so each unit is 0.025 mL, two and a half times the volume of a U-100 unit. The calculators on this site use the U-100 scale only.
Why do units not equal mcg or mg?
A unit on the syringe is a volume mark. The mass in that volume depends on how much peptide is in the vial and how much liquid was added, which is why the same reading can hold very different amounts from one vial to another.