Milligrams to Grams Converter

Nutrition and supplement labels mix units. Protein and sugar are usually listed in grams, while sodium, caffeine or vitamins appear in milligrams. To compare them, or to add two products together, bring everything into grams:

• 1500 mg is 1.5 g
• 500 mg is 0.5 g
• 250 mg is 0.25 g
• 25 mg is 0.025 g

Without the converter, move the decimal point three places to the left. 400 mg becomes 0.4 g, and 5 mg becomes 0.005 g. Fill the gaps with zeros, which is where most slips happen: 5 mg is not 0.05 g.

Totals are easier in one unit as well. Two 250 mg capsules plus one 500 mg capsule add up to 1000 mg, which is exactly 1 g.

Labels often write large milligram amounts with a thousands separator, as in 1,000 mg or 2,500 mg. Type them as printed: 1,000 is read as one thousand and converts to 1 g, and 2,500 converts to 2.5 g.

A European label may use a decimal comma instead, as in 1,25 mg. That works too, giving 0.00125 g, because a comma followed by one, two, or four or more digits is taken as the decimal mark. The one shape the converter has to guess at is a comma followed by exactly three digits, which it reads as thousands unless the number starts with 0. So 0,500 is half a milligram, but a decimal 1,250 should be typed as 1,25.

Very small results switch to scientific notation. Anything under 0.1 mg comes out this way: 0.05 mg shows as 5.0000e-5 g, which means 5 × 10⁻⁵, or 0.00005 g. Read the number after the e as how many places to move the point to the left.

This also tells you something about your scale. A jewellery or lab scale that reads to 0.001 g has a smallest step of 1 mg. Half a milligram (0.0005 g) is below that step, so the scale can't weigh it reliably, whatever the converter says.

Results under 1 g keep five significant digits, so 1 mg shows as 0.001 g and 25 mg as 0.025 g.