# mcg to mg Converter URL: https://speedycalculator.com/calculators/conversion/mcg-to-mg/ Last updated: 2026-10-25 > Convert micrograms (µg) to milligrams (mg): 1 microgram = 0.001 mg, so multiply by 0.001 or divide by 1,000. Both fields are editable, so you can also type in milligrams and get micrograms back. ## Inputs - Micrograms (µg) ## Results - Milligrams ## Formula ``` 1 µg = 0.001 mg 1 mg = 1,000 µg mg = µg × 0.001 ``` ## Explanation One milligram is 1,000 micrograms (mcg or µg). Vitamin labels mix the two: vitamin B12 and D are listed in mcg, vitamin C in mg. Always confirm doses with the label or a pharmacist. ### How to use the mcg to mg Converter - Type the number of micrograms into the **Micrograms** field. Decimals such as 500 are fine. - Read the answer in **Milligrams** – it updates as you type, with no button to press. - To convert the other way, type into **Milligrams** and the micrograms are recalculated. - Press **Copy results** to copy both values with the page title, or **Copy link** to share this exact conversion. This page converts only µg ⇄ mg. Need a different unit? Use the general weight converter, where you can choose any “from” and “to” unit. ### How it works Both units measure weight, so they are always in the same ratio: one microgram equals 0.001 milligrams. The calculator multiplies the number of micrograms you type by 0.001 to give milligrams, and when you type into the milligrams field it divides by the same factor to give micrograms. Because the ratio never changes, doubling the micrograms always doubles the milligrams. Results are calculated at full precision and rounded only for display (up to eight decimal places, with very large or small values shown in scientific notation). ### How to convert micrograms to milligrams - Write down the value in micrograms, for example **1,000 µg**. - Multiply by the conversion factor 0.001 (because 1 microgram = 0.001 mg). - 1,000 × 0.001 = **1 mg**. - To go back from milligrams to micrograms, divide by 0.001 – or multiply by 1,000. ### µg to mg conversion table MicrogramsMilligramsMilligramsMicrograms1 µg0.001 mg1 mg1000 µg10 µg0.01 mg2 mg2,000 µg25 µg0.025 mg5 mg5,000 µg50 µg0.05 mg10 mg10,000 µg100 µg0.1 mg20 mg20,000 µg250 µg0.25 mg50 mg50,000 µg400 µg0.4 mg100 mg100,000 µg500 µg0.5 mg1,000 mg1,000,000 µg1,000 µg1 mg2,500 µg2.5 mg5,000 µg5 mg ### What is a microgram? A microgram (µg or mcg) is one millionth of a gram. Potent medicines and some vitamins, such as B12, D and folate, are dosed in micrograms. Doctors often write “mcg” to avoid confusing µ with m. ### What is a milligram? A milligram is one thousandth of a gram. Medicine strengths, vitamins and minerals on supplement labels are usually given in milligrams. ### Common mistakes to avoid Confusing fluid ounces (volume) with ounces (weight), using troy ounces for food or regular ounces for gold, and mixing u.s. short tons, uk long tons and metric tonnes. ## Worked example Inputs — Micrograms: 1,000 µg. Results — **Milligrams = 1 mg**. ## FAQ **How many mcg in a mg?** 1,000. **How many mg is 500 mcg?** 0.5 mg. **How many milligrams are in one microgram?** 1 µg = 0.001 mg. **How many micrograms are in one milligram?** 1 mg = 1,000 µg. **How do I convert micrograms to milligrams?** Multiply the number of micrograms by 0.001. For example, 1,000 µg × 0.001 = 1 mg. **How do I convert milligrams back to micrograms?** Divide by 0.001 (or multiply by 1,000), or simply type the value into the milligrams field above. **What is 10 µg in milligrams?** 10 µg = 0.01 mg. **What is 100 µg in milligrams?** 100 µg = 0.1 mg. **Is this conversion exact?** Yes. The factor comes from the official definitions of both units (NIST and the SI), so the only difference you may see is rounding in the last displayed digit. **Can I convert to other units on this page?** This page converts only between micrograms and milligrams. To pick any weight unit, use the general weight converter linked under Related calculators. **What formula does the mcg to mg Converter use?** 1 µg = 0.001 mg. ## Sources - [NIST Special Publication 811 – Guide for the Use of the International System of Units](https://www.nist.gov/pml/special-publication-811) - [NIST Handbook 44 Appendix C – General tables of units of measurement](https://www.nist.gov/pml/owm/nist-handbook-44-current-edition)