Mass units
Convert grams to kilograms, pounds, ounces, tonnes and back. Metric and British units, historical Russian measures.
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Converter
Presets
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Russian historical mass units
historical Russian mass units (pre-1924)03
About mass units
The kilogram is the SI base unit of mass, defined via the Planck constant since 2019. British units (pound, ounce, stone) are still in use in the US, UK and Ireland — in medicine, cooking and body weight. The carat — 1 carat = 0.2 g, ISO 1000 standard, used in jewellery.
Careful with 'pound': the Russian funt (409.5 g) and the British pound (453.6 g) are different units with similar names.
Kilogram — base unit
SIkg — via Planck constant (2019)
Since 2019 the kilogram is defined via a fixed value of the Planck constant h = 6.626 070 15 × 10⁻³⁴ J·s. Before that — as the mass of the International Prototype in Sèvres near Paris.
British pound
US / UK1 lb = 453.592 g · 1 oz = 28.3495 g
The British pound, stone and ounce are still in use: medicine, cooking, body weight. The standard 'avoirdupois pound' = 16 ounces (of 28.35 g each). The troy ounce for precious metals — 31.1 g — is used in commodity trading.
Russian measures
pre-19241 pud = 40 funt = 16 380 g
The Russian mass system was used until 1924. Zolotnik = 4.266 g, Russian funt = 96 zolotniks = 409.5 g (different from the British pound!). Pud = 40 funts. Still found in historical and reference texts.
Mass vs Weight
PhysicsF = m·g · m — kg · F — N
Mass is a measure of inertia, in kilograms, independent of gravity. Weight is the force with which a body presses on a surface due to gravity, measured in newtons. On the Moon a person weighs ~6 times less, but has the same mass. Shop 'scales' actually measure mass.