Weight Calculator
Convert Between Weight Units: kg, lb, oz, stone, carat, grain & More
Weight Unit Converter
Weight Unit Reference Table
| Unit | Symbol | Equivalent (kg) | System | Common Use |
|---|---|---|---|---|
| Kilogram | kg | 1 | Metric (SI) | Scientific standard |
| Gram | g | 0.001 | Metric | Daily use |
| Milligram | mg | 0.000001 | Metric | Medicine, chemistry |
| Metric Ton | t | 1000 | Metric | Industrial, shipping |
| Pound | lb | 0.453592 | Imperial | US/UK daily use |
| Ounce | oz | 0.0283495 | Imperial | Cooking, packaging |
| Troy Ounce | troy oz | 0.0311035 | Specialized | Precious metals |
| Stone | st | 6.35029 | Imperial | UK body weight |
| US Ton | ton | 907.185 | US Custom | US shipping, industry |
| Carat | ct | 0.0002 | Specialized | Gems, diamonds |
| Grain | gr | 0.00006479891 | Specialized | Ammunition, pharmacy |
| Object | Mass (kg) | Scientific Notation |
|---|---|---|
| Electron | 0.000000000000000000000000000000910938 kg | 9.1 × 10⁻³¹ kg |
| Proton | 0.000000000000000000000000001672621 kg | 1.67 × 10⁻²⁷ kg |
| Atomic Mass Unit | 0.000000000000000000000000001660539 kg | 1.66 × 10⁻²⁷ kg |
| Moon | 73,477,000,000,000,000,000,000 kg | 7.35 × 10²² kg |
| Earth | 5,973,600,000,000,000,000,000,000 kg | 5.97 × 10²⁴ kg |
| Sun | 1,989,100,000,000,000,000,000,000,000,000 kg | 1.99 × 10³⁰ kg |
| Milky Way Galaxy | ~2 × 10⁴² kg | ~2 × 10⁴² kg |
History of Weight Measurement Systems
Early Babylonian and Egyptian records indicate weight measured by container capacities (gourds, clay vessels). Plant seeds served as measurement standards. Seeds and stones provided consistent references. The carat unit, still used for gems today, derives from carob seed consistency. Babylonians invented the talent as basic weight unit, divided into 60 parts (sexagesimal system).
Romans used 'uncia' (1/12 of Roman pound), from which English 'ounce' derived. Medieval Arabs measured weight using silver dirhem (45 barley grains). Ten dirhems made Wukyeh (450 grains, transliterated ounce). King Offa (8th century) halved dirhem to 222 grains, making ounce = 480 grains, pound = 5760 grains (avoirdupois system). This system evolved into British Imperial weights.
British Weights and Measures Act of 1824 officially defined imperial units. System later refined and reduced for consistency. Fire destroyed parliamentary standards (1855 - Houses of Parliament fire in London). New standards bureau established with imperial system prototypes. System came into official use across British Empire, adopted by United States.
Metric weights (gram, kilogram) developed by 18th-century French scientists. In 1791, French parliament imposed metric system nationwide. Kilogram defined as mass of 1 liter water at 4°C (water's maximum density point). Initial resistance in revolutionary France, but Napoleon abolished system (Emperor opposed). When Napoleon lost power, metric system was reinstated. Now standard in Continental Europe and many other parts of world.
| System | Origin | Base Logic | Usage Today |
|---|---|---|---|
| Metric (SI) | French 1790s | Decimal (powers of 10) | Science, most countries |
| Imperial | British Medieval | Historical ratios (12, 14, 16) | US, UK, some former colonies |
| Troy | Medieval France (Troyes) | 12 ounces per pound | Precious metals only |
| Specialized | Various origins | Industry-specific | Gems (carat), ammo (grain) |
- 1 milliliter water ≈ 1 cubic centimeter
- 1 milliliter water mass ≈ 1 gram
- 1 liter water mass ≈ 1 kilogram
- 1 cubic meter water mass ≈ 1000 kg (1 metric ton)
- US nickel weighs 5 grams
- US penny weighs 2.5 grams
- CD/DVD = 12 cm (120 mm) diameter
- 1 hectare = 10,000 square meters (football field sized)