The metric unit for measuring weight is the gram. The gram is a very small measurement (about 0.0353 of a U.S. ounce); therefore, the base measure is the kilogram (1,000 gr or 2.2046 lb).

Prefixes are added to gram to show multiples and submultiples, just as in length. The units used most often are the kilogram, the gram, and the millligram.

Conversion between units of mass in the metric system involves moving the decimal point to the right or to the left. Listing the units in order from largest to smallest will indicate how many places to move the decimal point and in which direction.

To convert 312 g to kilograms, first write the units in order from largest to smallest:

312 g = 0.312 kg