Convert grams to micrograms

µg = g × 1,000,000

Between the two sits the milligram: 1 g = 1,000 mg, and 1 mg = 1,000 µg. Most mistakes with this conversion come from stopping one step early.

The everyday version of this question is mcg to mg: divide micrograms by 1,000. A 500 mcg tablet is 0.5 mg; a 1,000 mcg vitamin B12 dose is 1 mg.

The official symbol is µg, using the Greek letter mu. Handwritten or printed small, µ can look like an m, turning a microgram dose into a milligram dose — a thousandfold error. For that reason medication safety bodies recommend writing mcg, and many supplement labels do. Both mean exactly the same unit.

• Vitamin D is often listed as 10 µg or 25 µg (400 or 1,000 IU)
• Vitamin B12 daily values are a few micrograms
• Folate is commonly listed in hundreds of micrograms

Converting those to grams gives numbers like 0.000025 g — accurate, and useless for reading a label, which is why labels stay in micrograms.

A grain of table salt weighs roughly 60 µg. A single eyelash is in the same range. A microgram is well below what any kitchen scale can register; laboratory balances that resolve one microgram sit in enclosures to shield them from air currents.

The reverse direction is on micrograms to grams.

Because micro means 10⁻⁶ under the SI prefixes in the SI Brochure published by the International Bureau of Weights and Measures (BIPM). On labels the unit is usually written “mcg”: the FDA’s 2016 Nutrition Facts rule moved vitamin D to micrograms, and the Institute for Safe Medication Practices lists the µg symbol as error-prone in medication orders because it is easily misread as mg.