Gram science definition

A gram is a unit of mass equal to one thousandth of a kilogram. Its symbol is g. In scientific writing, mass and weight are different quantities: mass describes an amount of matter, while weight involves gravitational force.

Meaning and context

A laboratory balance may display a sample’s mass in grams. For smaller quantities, milligrams are often convenient: one gram equals one thousand milligrams. For larger quantities, one thousand grams equals one kilogram. Keep the unit attached to the number when recording a result.

Examples and usage

For example, a sample with a mass of 2.5 g has a mass of 2,500 mg. This is a unit conversion, not a change in the physical sample. Moving the decimal point without identifying the original and target units makes errors harder to spot.

What to check

Use g rather than an improvised plural symbol such as gs. A gram is not a unit of volume, so grams and milliliters cannot always be exchanged numerically. Converting between mass and volume requires the material’s density and the relevant conditions.

Explore more: Word meanings and writing guides