Base Unit Method

Category-Specific Formula

Weight vs Mass

Mass is the amount of matter in an object (measured in kg), while weight is the force gravity exerts on that mass (measured in newtons). In everyday use, we often use 'weight' to mean 'mass'.

The Kilogram Standard

Since 2019, the kilogram is defined by fundamental physical constants rather than a physical prototype. This provides unprecedented accuracy and stability for mass measurements worldwide.

Imperial System Origins

The pound comes from the Roman 'libra' (hence lb). The stone (14 pounds) is primarily used in UK and Ireland for body weight. The ounce has different definitions for weight (avoirdupois) vs volume (fluid).

Cooking and Recipe Conversions

Recipe conversions require careful attention to whether ingredients are measured by weight or volume. Professional baking typically uses weight measurements for consistency and accuracy.