100 mcg to units
100 mcg (0.1 mg) is 4 units on a U-100 insulin syringe when the vial is 2.5 mg/mL, and 2 units at 5 mg/mL. The answer changes with concentration: units = mg ÷ mg/mL × 100.
100 mcg in units, by concentration
Find the concentration of your vial in the left column. If you do not know it, divide the mg in the vial by the mL of water added.
| Concentration | Volume | 100 mcg = |
|---|---|---|
| 1 mg/mL · 5 mg vial + 5 mL | 0.1 mL | 10 units |
| 2 mg/mL · 10 mg vial + 5 mL | 0.05 mL | 5 units |
| 2.5 mg/mL · 5 mg vial + 2 mL | 0.04 mL | 4 units |
| 3 mg/mL · 15 mg vial + 5 mL | 0.03333 mL | 3.333 units |
| 5 mg/mL · 10 mg vial + 2 mL | 0.02 mL | 2 units |
| 7.5 mg/mL · 15 mg vial + 2 mL | 0.01333 mL | 1.333 units · too small to read reliably |
| 10 mg/mL · 10 mg vial + 1 mL | 0.01 mL | 1 unit · too small to read reliably |
| 15 mg/mL · 30 mg vial + 2 mL | 0.006667 mL | 0.6667 units · too small to read reliably |
| 20 mg/mL · 20 mg vial + 1 mL | 0.005 mL | 0.5 units · too small to read reliably |
100 mcg in units, by vial size and water added
The same conversion, starting from what is printed on the vial and how much bacteriostatic water went in.
| Vial | 1 mL water | 2 mL water | 3 mL water |
|---|---|---|---|
| 2 mg | 5 units | 10 units | 15 units |
| 5 mg | 2 units | 4 units | 6 units |
| 10 mg | 1 unit · too small to read reliably | 2 units | 3 units |
| 15 mg | 0.6667 units · too small to read reliably | 1.333 units · too small to read reliably | 2 units |
Calculate for your vial
The amount is filled in. Add your vial size and the water added.
Enter the vial size and the water you added.
Arithmetic only. This tool does not recommend a dose; use the one your prescriber gave you.
Questions
How many units is 100 mcg?
It depends on the concentration of the vial. At 2.5 mg/mL (5 mg vial + 2 mL) 100 mcg is 4 units on a U-100 insulin syringe. At 5 mg/mL (10 mg vial + 2 mL) it is 2 units.
Why is there no single answer for 100 mcg in units?
Units measure volume: 100 units is 1 mL. Milligrams and micrograms measure the amount of substance. The link between them is the concentration, which is set by how much water was added to the vial.
How many mL is 100 mcg?
Divide 0.1 mg by the concentration in mg/mL. At 2.5 mg/mL that is 0.04 mL; at 5 mg/mL it is 0.02 mL.
How many mg is 100 mcg?
100 mcg is 0.1 mg. There are 1,000 mcg in 1 mg.
What if 100 mcg comes to less than 2 units?
Below about 2 units the marks on an insulin syringe are too coarse to read reliably. At 7.5, 10, 15 and 20 mg/mL, 100 mcg is under 2 units. A weaker mix (more water in the same vial) makes the same amount a larger, easier volume to read.
The same amount written the other way: 0.1 mg to units.
Nearby conversions
- 50 mcg to units
- 150 mcg to units
- 200 mcg to units
- 250 mcg to units
- 300 mcg to units
- 400 mcg to units
- 0.05 mg to units
- 0.1 mg to units
- 35 units to mg
- 10 units to mL
- 0.5 mL to units
- mcg to mg
- All conversions