Grams to Milligrams (g to mg)

How to convert grams to milligrams

Multiply the grams by 1,000:

mg = g × 1,000

2.5 g × 1,000 = 2,500 mg. Multiplying by 1,000 moves the decimal point three places to the right, filling in zeros as needed:

The prefix milli- means one thousandth in every SI unit, the same as in millimeter and milliliter. To go the other way, divide milligrams by 1,000 — see mg to grams.

Grams to milligrams chart

Nutrition labels

U.S. Nutrition Facts labels give fat, carbohydrate, sugar and protein in grams, but sodium, cholesterol and many vitamins and minerals in milligrams. Converting puts them on one scale: 2.3 g of sodium is the 2,300 mg Daily Value, and a snack with 0.4 g of sodium has 400 mg. Caffeine, too, is stated in milligrams: the FDA lists about 71 mg in 12 fluid ounces of black tea — 0.071 g.

Milligrams on a scale

Most kitchen scales read to 1 g, so they cannot weigh a few hundred milligrams accurately: 250 mg is a quarter of their smallest step. Pocket or jewelry scales that read to 0.01 g show 0.25 g directly, and laboratory balances read to 0.001 g — one milligram. When a recipe or a formula gives an amount in milligrams, convert it to grams and check that your scale’s smallest step is at least ten times smaller than the amount; otherwise weigh a larger batch and divide. For larger weights, kg to grams uses the same factor of 1,000.

Supplements, medicine and small amounts

Supplements list their doses in milligrams or micrograms; one gram of a powder is 1,000 mg, so a 500 mg capsule holds half a gram. For medicine, always follow the label or a pharmacist: liquid medicines are dosed by concentration, such as mg per mL, and kitchen spoons are not accurate enough. In the kitchen, grams are usually the smallest unit worth measuring, but jewelry scales and lab balances that read to 0.001 g weigh to the milligram. For grams and ounces, use grams to ounces; for micrograms, mcg to mg.