100 mcg to units on an insulin syringe
100 mcg to units depends on how strong your vial is. At 2.5 mg/mL, 100 mcg (0.1 mg) is 4 units on a U-100 insulin syringe. Use the calculator for your own vial and water, or find your mix in the chart below.
Units to draw
15units
Draw 15 units on a U-100 syringe, halfway between the 14- and 16-unit marks.
- Dose
- 100 mcg (0.1 mg)
- Volume
- 0.15 mL
- Concentration
- 666.67 mcg/mL (0.66667 mg/mL)
- Per unit
- 6.67 mcg (0.00667 mg)
- Full doses in vial
- 20
Show the math
- Convert the vial amount to mcgmg × 1,000 = mcg2 mg × 1,000 = 2,000 mcg
- Concentrationvial (mcg) ÷ water (mL) = mcg per mL2,000 mcg ÷ 3 mL = 666.67 mcg/mL (0.66667 mg/mL)
- Volume to drawdose (mcg) ÷ concentration (mcg/mL) = mL100 mcg ÷ 666.67 mcg/mL = 0.15 mL
- Units to drawmL × units per mL = units0.15 mL × 100 units/mL = 15 units
- Amount in each unitmcg per mL ÷ units per mL = mcg per unit666.67 mcg/mL ÷ 100 units/mL = 6.67 mcg per unit (0.00667 mg)
- Doses in the vialvial (mcg) ÷ dose (mcg), rounded down2,000 mcg ÷ 100 mcg = 20 full doses
100 mcg to units chart
Units on a U-100 syringe for 100 mcg at common vial sizes and water volumes, calculated by this site. A dash means 100 mcg is more than the whole vial.
| 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 units | 2 units | 3 units |
| 15 mg | 0.7 units | 1.3 units | 2 units |
| 20 mg | 0.5 units | 1 units | 1.5 units |
| 30 mg | 0.3 units | 0.7 units | 1 units |
Across these mixes, 100 mcg measures between 2 and 15 units where it fits one syringe. In 9 mixes it is under 2 units, too small to read reliably.
100 mcg to units by concentration
If you already know your concentration in mg per mL, read it straight from this table.
| Concentration | Units (U-100) | Volume |
|---|---|---|
| 0.5 mg/mL (500 mcg/mL) | 20 units | 0.2 mL |
| 1 mg/mL (1,000 mcg/mL) | 10 units | 0.1 mL |
| 2 mg/mL (2,000 mcg/mL) | 5 units | 0.05 mL |
| 2.5 mg/mL (2,500 mcg/mL) | 4 units | 0.04 mL |
| 5 mg/mL (5,000 mcg/mL) | 2 units | 0.02 mL |
| 10 mg/mL (10,000 mcg/mL) | 1 units | 0.01 mL |
How do you convert 100 mcg to units?
Divide the amount in mcg by ten times your concentration in mg/mL: units = mcg ÷ (10 × mg/mL). For 100 mcg at 2.5 mg/mL that is 100 ÷ (10 × 2.5) = 4 units.
Your concentration is the peptide in the vial divided by the water you added: a 2 mg vial with 3 mL of water is 0.67 mg/mL. The reconstitution math guide shows every step.
Which syringe fits 100 mcg?
With a 2 mg vial and 3 mL of water, 100 mcg is 15 units, which fits a 0.3 mL (30-unit) U-100 syringe. Smaller barrels have wider spacing between marks, so they are easier to read for small amounts.
See the insulin syringe units chart for how each syringe size is marked.
Frequently asked questions
How many units is 100 mcg?
It depends on the concentration of your vial. At 2.5 mg/mL, 100 mcg is 4 units on a U-100 syringe; at 5 mg/mL it is 2 units.
Is 100 mcg the same number of units on a 30, 50 and 100-unit syringe?
Yes, if they are all U-100 syringes. Every U-100 syringe holds 100 units per mL; the barrel size only changes how many units fit and how easy the marks are to read.
How many units is 100 mcg on a U-40 or U-50 syringe?
Fewer units, because each unit holds more liquid. With a 2 mg vial and 3 mL of water, 100 mcg is 15 units on U-100, 7.5 on U-50 and 6 on U-40.
What is 100 mcg in mg?
100 mcg is 0.1 mg. There are 1,000 mcg in 1 mg.