What Does mg Stand For?
Small mg means milligram, a thousandth of a gram. Capital-M Mg is the chemical symbol for magnesium. Here is how to tell them apart.
mg = milligram
mg stands for milligram, a unit of mass in the metric system. "Milli" means one thousandth, so 1 mg = 0.001 g. You see it on medicine, vitamin and food labels, and in lab work whenever small amounts are weighed.
| Unit | In mg | In grams |
|---|---|---|
| 1 milligram (mg) | 1 | 0.001 g |
| 1 gram (g) | 1,000 | 1 g |
| 1 kilogram (kg) | 1,000,000 | 1,000 g |
| 1 microgram (mcg or µg) | 0.001 | 0.000001 g |
Mg = magnesium
In chemistry, Mg (capital M, lowercase g) is the symbol for the element magnesium, atomic number 12. It forms the Mg²⁺ ion, which is why you see compounds such as MgO (magnesium oxide) and MgCl₂ (magnesium chloride). Capitalisation matters: mg is a mass, Mg is an element, so "25 mg of Mg" is a perfectly sensible sentence.
mg on medicine labels
A label that says "500 mg" gives the amount of active ingredient per tablet or per dose. For liquids it is usually given per volume, such as 250 mg per 5 ml, which means 50 mg in each ml. Always follow the label or a pharmacist for doses.
Converting mg
- mg to g: divide by 1,000 (2,500 mg = 2.5 g).
- g to mg: multiply by 1,000 (0.4 g = 400 mg).
- mg to mcg: multiply by 1,000 (0.5 mg = 500 mcg).
- mg to ml: needs a concentration, use the mg to ml Converter.
To work out moles from a mass of magnesium, use the Molar Mass Calculator(Mg is 24.305 g/mol).
Frequently asked questions
What does mg stand for?
Lowercase mg stands for milligram, a unit of mass equal to one thousandth of a gram. In chemistry, Mg with a capital M is the symbol for the element magnesium.
What does mg stand for in medicine?
On medicine labels, mg means milligrams of the active ingredient. A 500 mg tablet contains 500 milligrams (0.5 g) of the drug.
How many mg are in a gram?
There are 1,000 mg in 1 gram, and 1,000,000 mg in 1 kilogram. To convert grams to mg, multiply by 1,000.
Is mg the same as ml?
No. mg measures mass and ml (millilitres) measures volume. Converting between them needs a concentration or density; see the mg to ml converter.
Is mcg the same as mg?
No. mcg (or µg) is a microgram, one thousandth of a milligram. 1 mg = 1,000 mcg, so mixing them up gives a dose 1,000 times off.
