Mcg to mg Calculator
Convert micrograms to milligrams by dividing by 1,000. This calculator also shows the equivalent in grams, nanograms, and Vitamin D International Units for supplement labels.
The microgram (mcg or µg) and milligram (mg) are both metric mass units, with 1,000 micrograms making up one milligram. Getting this conversion right matters for medications and supplements, where a 1,000-fold error can be dangerous.
Formula: mg = mcg / 1,000
Metric Mass Scale:
| Unit | Symbol | In Grams |
|---|---|---|
| Kilogram | kg | 1,000 g |
| Gram | g | 1 g |
| Milligram | mg | 0.001 g |
| Microgram | mcg (µg) | 0.000001 g |
| Nanogram | ng | 0.000000001 g |
Common Supplement Conversions:
| Supplement | Common Dose | In mg |
|---|---|---|
| Vitamin D | 1,000 mcg (40,000 IU) | 1 mg |
| Vitamin B12 | 500 mcg | 0.5 mg |
| Folic acid | 400 mcg | 0.4 mg |
| Selenium | 200 mcg | 0.2 mg |
| Chromium | 200 mcg | 0.2 mg |
| Biotin | 5,000 mcg | 5 mg |
Vitamin D note: Vitamin D labels sometimes use IU (International Units) instead of mcg. The conversion is 1 mcg of Vitamin D = 40 IU. So 25 mcg = 1,000 IU, and 125 mcg = 5,000 IU.