microgram

Everyday

A unit of mass equal to one millionth of a gram; its symbol is µg (sometimes mcg on medicine labels). tree →

In the lessons

In science and on vitamin or medicine labels, micrograms measure very tiny amounts, such as vitamin D or vitamin B12. In maths, conversions: 1 gram = 1000 milligrams = 1 000 000 micrograms; 1 milligram = 1000 micrograms. Phrases: «micrograms of vitamin D», «per microgram», «µg».

Examples

• The vitamin tablet has 10 micrograms of vitamin D. tree →
• One milligram equals one thousand micrograms. tree →
• A grain of sand weighs much more than a microgram. tree →
• The label says «400 µg of folic acid». tree →
• Scientists measure tiny amounts of poison in micrograms. tree →
• How many micrograms are in half a milligram? Five hundred. tree →
• Medicine doses in micrograms must be measured very carefully. tree →

Note

Plural «micrograms». Symbol µg (µ is the Greek letter mu) or «mcg». Maths: micro = one millionth; to change grams to micrograms multiply by 1 000 000; milligrams to micrograms multiply by 1000. Trap: do not mix up mg (milligram) and µg (microgram) — a microgram is 1000 times smaller. Safety: only adults should give medicines.