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Milligrams to micrograms

Multiply milligrams by 1,000 to get micrograms.

1 mg = 1,000 mcgBIPM SI
mg
10,000mcg

10 mg = 10,000 mcg

How to convert milligrams to micrograms

The microgram is one millionth of a gram (10⁻⁹ kg), written mcg in medicine. The milligram is one thousandth of a gram (10⁻⁶ kg).

Worked example — 10 mg: 10 × 1,000 = 10,000 mcg.

Milligrams to micrograms table

Common conversions. The reverse table is on micrograms to milligrams.
MilligramsMicrograms
0.5 mg500 mcg
1 mg1,000 mcg
2 mg2,000 mcg
5 mg5,000 mcg
10 mg10,000 mcg
25 mg25,000 mcg
50 mg50,000 mcg
100 mg100,000 mcg
500 mg500,000 mcg

Reverse and related

About milligrams and micrograms

Milligram (mg)

1 mg = 1,000 mcg

Definition. One thousandth of a gram (10⁻⁶ kg)

History and origin

The milligram is one thousandth of a gram, part of the decimal metric system. Its small size suits doses and trace amounts.

Current use

Milligrams are the everyday unit for medication doses and for nutrients on food labels.

Source: BIPM, The International System of Units (SI), 9th ed. (2019)

Microgram (mcg)

1 mcg = 0.001 mg

Definition. One millionth of a gram (10⁻⁹ kg), written mcg in medicine

History and origin

The microgram is one millionth of a gram, a thousandth of a milligram. In medicine it is written mcg rather than µg to avoid a handwritten mix-up with mg.

Current use

Micrograms measure very small doses of vitamins and drugs, such as vitamin D, folic acid and thyroid medication.

Source: BIPM, The International System of Units (SI), 9th ed. (2019)

Where people use this

Milligrams: medication doses, nutrition labels. Micrograms: vitamin and drug doses. 1 mg is exactly 1000 mcg.

How we know this is right
The factor is fixed by the standards that define the units, not chosen — so it is exact, not a measurement:
1 mcg = 0.001 mg, so 1 mg = 1 ÷ 0.001 = 1,000 mcg.

Every value is carried to full double precision; the display is rounded.

Both units are defined in BIPM, The International System of Units (SI), 9th ed. (2019).

Questions people ask

How many mcg in a mg?

One milligram is exactly 1000 micrograms.

How many mcg is 5 mg?

5 mg is 5000 mcg.

How many mcg is 0.5 mg?

Half a milligram is 500 mcg.

All milligram conversions