How to convert mcg to units
Divide the dose in mcg by the strength in mcg/mL, then multiply by 100 for a U-100 syringe, where 100 units are 1 mL.[1]
units = dose (mcg) ÷ strength (mcg/mL) × 100
strength in mcg/mL = strength in mg/mL × 1,000
Example. 250 mcg from a 1 mg/mL liquid. 1 mg/mL is 1,000 mcg/mL. 250 ÷ 1,000 = 0.25 mL = 25 units.
mcg to units chart
| Dose | 0.5 mg/mL (500 mcg/mL) | 1 mg/mL (1,000 mcg/mL) | 2 mg/mL (2,000 mcg/mL) | 5 mg/mL (5,000 mcg/mL) | 10 mg/mL (10,000 mcg/mL) |
|---|---|---|---|---|---|
| 50 mcg | 10 | 5 | 2.5 | 1 | 0.5 |
| 100 mcg | 20 | 10 | 5 | 2 | 1 |
| 200 mcg | 40 | 20 | 10 | 4 | 2 |
| 250 mcg | 50 | 25 | 12.5 | 5 | 2.5 |
| 300 mcg | 60 | 30 | 15 | 6 | 3 |
| 500 mcg | 100 | 50 | 25 | 10 | 5 |
| 750 mcg | – | 75 | 37.5 | 15 | 7.5 |
| 1,000 mcg | – | 100 | 50 | 20 | 10 |
Dashes mean more than 100 units, the capacity of a 1 mL insulin syringe.[3]
100, 250, 300 and 500 mcg to units
At 1 mg/mL, each U-100 unit holds 10 mcg, so 100 mcg is 10 units, 200 mcg is 20, 250 mcg is 25, 300 mcg is 30 and 500 mcg is 50 units. At 2 mg/mL every answer halves: 100 mcg is 5 units and 500 mcg is 25. At 5 mg/mL, 300 mcg is 6 units on the insulin syringe.
Write it “mcg”, with a zero before the point
The Institute for Safe Medication Practices lists “µg” as an error-prone abbreviation because it can be misread as “mg”, a 1,000-fold error. It recommends writing “mcg”. It also warns against a trailing zero (“1.0 mg” read as “10 mg”) and a missing leading zero (“.5 mg” read as “5 mg”).[2]
Before converting, rewrite your dose and the strength in the same unit. The calculator handles mg and mcg in both boxes, so you can enter them exactly as they are printed.
Decimal slips and unit mix-ups are covered in syringe measuring mistakes. If your strength is printed as a total such as 500 mcg in 2 mL, the strength calculator converts it. To check how much a reading already in the syringe contains, use units to mg.
Frequently asked questions
100 mcg to units: how many units is 100 mcg?
At 1 mg/mL (1,000 mcg/mL), 100 mcg is 0.1 mL, which is 10 units on a U-100 syringe. At 2 mg/mL it is 5 units.
250 mcg to units: how many units is 250 mcg?
At 1 mg/mL it is 25 units (0.25 mL); at 5 mg/mL it is 5 units.
500 mcg to units: how many units is 500 mcg?
500 mcg is 0.5 mg. At 1 mg/mL it is 50 units; at 5 mg/mL it is 10 units.
200 mcg to units: how many units is 200 mcg?
At 1 mg/mL it is 20 units (0.2 mL); at 2 mg/mL it is 10 units.
How many mcg are in one unit?
One U-100 unit is 0.01 mL. Multiply by the strength in mcg/mL: at 1 mg/mL (1,000 mcg/mL) each unit holds 10 mcg.