Conversion table
| Micrograms (mcg) | International Units (IU) |
|---|---|
| 10 mcg | 400 |
| 15 mcg | 600 |
| 20 mcg | 800 |
| 25 mcg | 1000 |
| 50 mcg | 2000 |
| 100 mcg | 4000 |
| 125 mcg | 5000 |
| 250 mcg | 10000 |
How to convert mcg to IU
IU = mcg × (factor)vitamin D = 40 IU/mcg · reverse: mcg = IU ÷ factor
- mcg
- micrograms of the vitamin
- IU
- the equivalent International Units
- factor
- IU per mcg, set by the vitamin and form
Because IU is form-specific, converting only makes sense for a named substance. This is reference information, not dosing advice.
Frequently asked questions
How many IU is 25 mcg of vitamin D?
25 mcg of vitamin D is 1000 IU, since the factor is 40 IU per microgram.
How many mcg is 5000 IU of vitamin D?
5000 IU is 125 mcg of vitamin D.
Why is there no single mcg-to-IU number?
Because an IU is defined by biological activity for each substance, so vitamin D, A and E all use different factors.
What is 1 mcg of vitamin A in IU?
About 3.33 IU as retinol (RAE); beta-carotene forms use smaller factors.