Grams to Milligrams Converter

Exactly 1000. The relationship is fixed by the SI definition of the milligram as one-thousandth of a gram, so 1 g = 1000 mg with no rounding. Going further down the scale, 1 mg = 1000 mcg, which means 1 g = 1,000,000 mcg. Follow the unit and strength on a medication label rather than inferring a dose from a unit conversion.

500 mg equals 0.5 g. Divide milligrams by 1000 to get grams, or multiply grams by 1000 to get milligrams. This arithmetic converts units only and does not determine a medication dose.

Medication labels use the unit that keeps the number readable. Confusing grams with milligrams creates a 1000-fold error, so check the printed unit and concentration every time. This converter checks unit arithmetic only and must not be used to choose or measure a dose.

Because the active doses are small enough that mg would force awkward decimals. Vitamin B12 is sold at 25 to 1000 mcg (0.025 to 1 mg) per tablet, folic acid at 400 to 800 mcg, biotin at 30 to 300 mcg, iodine at 150 mcg, and selenium at 55 to 200 mcg. Writing those as 0.0004 mg or 0.000150 g would be harder to read and easier to misdose, so labels switch units. 1 mg = 1000 mcg and 1 g = 1,000,000 mcg, all exact. US drug labels prefer mcg over the symbol ug because handwritten ug can be misread as mg, which would multiply the dose 1000-fold.

100 mg equals 0.1 g, or one tenth of a gram. Divide milligrams by 1000 to get grams. Other reference points are 10 mg = 0.01 g, 50 mg = 0.05 g, 250 mg = 0.25 g, and 1000 mg = 1 g.