The Metric System of Measurements uses the mass units: gram (g), kilogram (kg) and tonne (t).

1000 g = 1 kg

1000 kg = 1 tonne

Adding prefixes of the International System of Units (SI) allows to express weight as multiples or fractions of 1 gram:

1 gigatonne (Gt) =1 000 000 000 000 000 g

1 megatonne (Mt) =1 000 000 000 000 g

1 tonne (t) =1 000 000 g

1 kilogram (kg) =1 000 g

1 gram (g) =1 g

1 milligram (mg) =0.001 g

1 microgram (µg) =0.000 001 g

1 nanogram (ng) =0.000 000 001 g

1 picogram (pg) =0.000 000 000 001g

Imperial and US weight units can also be expressed as metric units:

Metric units

1 US ton (ton) =0.907 tonne

1 UK ton (ton) =1.016 tonne

1 lb (pound) =453.59 g

1 oz (ounce) =28.35g

Further information on the International System of Units (SI) is provided by the International Bureau of Weights and Measures (BIPM)