Sprint 8 Converter + Math
Weight & Mass Converter
Universal conversion engine with resilient numeric parsing.
Result
10.000000
How it works
Weight and mass are technically different physical quantities — mass is the amount of matter (measured in kilograms), while weight is the gravitational force on that mass (measured in newtons). In everyday use, however, "weight" and "mass" are used interchangeably because we all live at approximately the same gravitational acceleration (g ≈ 9.81 m/s²). The Weight & Mass Converter handles both contexts: it converts across all common mass units for everyday use, and also supports newtons and kilonewtons for engineering contexts where true weight (force) matters.
**Unit coverage** Metric: milligrams, grams, kilograms, metric tonnes (1000 kg). Imperial/US: ounces (avoirdupois), pounds, US short tons (2000 lb), UK long tons (2240 lb), stones. Scientific: atomic mass units (u or Da, used in chemistry), carats (200 mg each, used in gemstones), troy ounces (used for precious metals — 31.1035 g, not the same as the avoirdupois ounce of 28.3495 g). Force: newtons, kilonewtons.
**Important distinctions** The troy ounce vs. avoirdupois ounce difference matters when dealing with gold, silver, or pharmaceutical compounds. Troy system: 12 troy ounces per troy pound. Avoirdupois system: 16 ounces per pound. Gold prices quoted in troy oz; kitchen recipes use avoirdupois oz — confusing these causes 9.7% errors.
Stones (used informally in the UK for body weight) = 14 pounds. A "14-stone person" weighs 196 pounds = 88.9 kg.
**Engineering context** Force converters (N, kN) are essential for structural engineering, where load calculations are expressed in newtons but material specifications may be in pounds-force or kilograms-force. 1 kgf = 9.80665 N exactly.
Privacy: all conversions run in the browser. No data is transmitted.
Frequently Asked Questions
- Mass is the amount of matter in an object, measured in kilograms (kg). Weight is the gravitational force on that mass, measured in newtons (N). Weight = mass × gravitational acceleration. On the Moon (g ≈ 1.62 m/s²), your mass is the same but your weight is about 1/6 of your Earth weight. In everyday life we say 'weight' when we mean 'mass' because gravitational acceleration barely varies across Earth's surface.
- The avoirdupois ounce (used for general goods) = 28.3495 g = 1/16 pound. The troy ounce (used for precious metals and gems) = 31.1035 g = 1/12 troy pound. Troy weight originates from the French trade city of Troyes and has been used for precious metals since medieval times. Gold, silver, platinum, and pharmaceutical compounds are priced per troy ounce — not avoirdupois. Confusing the two would introduce a 9.7% error.
- 1 stone = 14 pounds = 6.35029 kg. The stone is an informal unit still commonly used in the UK and Ireland for body weight — you'll see '12 stone 8' on British bathroom scales (= 176 lbs = 79.8 kg). It is not a legal unit in the UK for trade, but remains in widespread colloquial use.
- No — these are two different uses of the word 'carat'. For gemstones (diamonds, rubies, sapphires), 1 carat = 200 mg = 0.2 g — a unit of mass. For gold purity, 'carat' (or 'karat' in US spelling) is a fraction of 24: 24-carat gold = pure gold; 18-carat gold = 18/24 = 75% gold by mass. Despite the same name, gemstone carats and gold carats are unrelated measures.