The ounce equals 28.35 grams and is 1/16 of a pound. It is common in American and British cooking for small ingredient weights. The fluid ounce (29.57 ml in the US, 28.41 ml in the UK) is a volume unit and is completely different from the mass ounce.
Real-world: A US tin of tuna is 5 oz (142 g). A Starbucks grande coffee is 16 fl oz (473 ml). Gold is traded in troy ounces (31.10 g).
Read full ounce reference →The kilogram is the SI base unit of mass. Since 2019 it has been defined via the fixed numerical value of Planck's constant — a major shift from the previous definition based on a physical artifact. One litre of water at 4 °C has a mass of almost exactly 1 kg, a coincidence designed into the original 1795 definition.
Real-world: A litre of water weighs 1 kg at 4 °C. An average adult weighs 60–90 kg. A standard bag of flour is 1 kg.
Read full kilogram reference →