Question 1

How many units is 250 mcg?

Accepted Answer

At 2,500 mcg/mL (a 5 mg vial with 2 mL of water) 250 mcg is 0.1 mL, which is 10 units on a U-100 syringe. At 5,000 mcg/mL (10 mg with 2 mL) it is 5 units, and at 1,000 mcg/mL (2 mg with 2 mL) it is 25 units. The microgram figure alone cannot give one answer — the concentration you mixed decides it.

Question 2

How many units is 200 mcg on an insulin syringe?

Accepted Answer

At 2,500 mcg/mL (a 5 mg vial with 2 mL of water) 200 mcg is 0.08 mL, which is 8 units on a U-100 syringe. At 5,000 mcg/mL (10 mg with 2 mL) it is 4 units, and at 1,000 mcg/mL (2 mg with 2 mL) it is 20 units. The microgram figure alone cannot give one answer — the concentration you mixed decides it.

Question 3

How many units is 100 mcg on an insulin syringe?

Accepted Answer

At 2,500 mcg/mL (a 5 mg vial with 2 mL of water) 100 mcg is 0.04 mL, which is 4 units on a U-100 syringe. At 5,000 mcg/mL (10 mg with 2 mL) it is 2 units, and at 1,000 mcg/mL (2 mg with 2 mL) it is 10 units. The microgram figure alone cannot give one answer — the concentration you mixed decides it.

Question 4

How many units is 300 mcg?

Accepted Answer

At 2,500 mcg/mL (a 5 mg vial with 2 mL of water) 300 mcg is 0.12 mL, which is 12 units on a U-100 syringe. At 5,000 mcg/mL (10 mg with 2 mL) it is 6 units, and at 1,000 mcg/mL (2 mg with 2 mL) it is 30 units. The microgram figure alone cannot give one answer — the concentration you mixed decides it.

Question 5

How many units is 500 mcg?

Accepted Answer

At 2,500 mcg/mL (a 5 mg vial with 2 mL of water) 500 mcg is 0.2 mL, which is 20 units on a U-100 syringe. At 5,000 mcg/mL (10 mg with 2 mL) it is 10 units, and at 1,000 mcg/mL (2 mg with 2 mL) it is 50 units. The microgram figure alone cannot give one answer — the concentration you mixed decides it.

Question 6

What is the formula for mcg to units?

Accepted Answer

Units = (dose in mcg ÷ concentration in mcg/mL) × 100 on a U-100 syringe. The concentration is the vial's contents in micrograms divided by the millilitres of water you added: a 5 mg vial is 5,000 mcg, and with 2 mL of water that is 2,500 mcg/mL. Use × 40 instead of × 100 on a U-40 veterinary barrel.

Question 7

Is a unit on an insulin syringe the same as a microgram?

Accepted Answer

No. A syringe unit is a volume — one hundredth of a millilitre on a U-100 barrel. A microgram is a mass. The number of micrograms in one unit depends on how concentrated your solution is: 25 mcg per unit at 2,500 mcg/mL, 50 mcg per unit at 5,000 mcg/mL.

Dose	1,000 mcg/mL2 mg + 2 mL	2,000 mcg/mL2 mg + 1 mL	2,500 mcg/mL5 mg + 2 mL	5,000 mcg/mL10 mg + 2 mL	10,000 mcg/mL10 mg + 1 mL
50 mcg	5 units0.05 mL	2.5 units0.025 mL	2 units0.02 mL	1 units0.01 mL	0.5 units0.005 mL
100 mcg	10 units0.1 mL	5 units0.05 mL	4 units0.04 mL	2 units0.02 mL	1 units0.01 mL
200 mcg	20 units0.2 mL	10 units0.1 mL	8 units0.08 mL	4 units0.04 mL	2 units0.02 mL
250 mcg	25 units0.25 mL	12.5 units0.125 mL	10 units0.1 mL	5 units0.05 mL	2.5 units0.025 mL
300 mcg	30 units0.3 mL	15 units0.15 mL	12 units0.12 mL	6 units0.06 mL	3 units0.03 mL
500 mcg	50 units0.5 mL	25 units0.25 mL	20 units0.2 mL	10 units0.1 mL	5 units0.05 mL
1,000 mcg	100 units1 mL	50 units0.5 mL	40 units0.4 mL	20 units0.2 mL	10 units0.1 mL

mcg to Units Calculator for an Insulin Syringe

Set up your vial

The formula

mcg to units table (U-100 syringe)

Can you actually read that mark?

U-40 and the other conversions people mix up

Common questions

Sources