Weight Converter
Convert between weight units — kilograms (kg), pounds (lb), grams (g), ounces (oz), stones (st), tonnes, quintals, short and long tons, troy ounces, grains and carats. Pick any two; it runs entirely in your browser.
Every factor is exact, anchored to the kilogram. The international pound has been exactly 0.45359237 kilograms since 1959, an ounce is a sixteenth of a pound, a stone is fourteen pounds, a short ton is 2,000 pounds and a long ton is 2,240. A grain is exactly 1/7000 of a pound and a metric carat is exactly 200 milligrams. So the live tool and the numbers on every page below always agree.
Weight or mass — does the difference matter here?
Strictly, mass is how much matter something contains and weight is the force gravity pulls it with, so a bag of rice has the same mass on the Moon but weighs about a sixth as much. In everyday use the two words are swapped freely: bathroom scales, shop scales and freight documents all say "weight" while actually measuring mass. Every unit on this page is a unit of mass, and because you are almost certainly weighing things on Earth, converting between them gives the answer you want either way.
The three different "tons"
"Ton" is the most dangerous word on this page, because it means three different masses. The tonne (metric ton) is exactly 1,000 kg and is what most of the world means. The short ton is 2,000 pounds and is what the United States means. The long ton is 2,240 pounds — the traditional British ton, still used in shipping. The tonne and the long ton are close enough to be mistaken for each other, and the short ton is noticeably lighter than both, so a contract priced "per ton" is worth different amounts depending on which one was intended.
Ounces, troy ounces and carats
An ordinary ounce is a sixteenth of a pound and is what food packaging means. A troy ounce is a different, heavier unit — 480 grains against 437.5 — and it is the one gold, silver and platinum are priced in, so "an ounce of gold" is about ten per cent more metal than an ounce of anything else. A carat is different again: exactly 200 milligrams, used for gemstones. Do not confuse it with karat, which describes how pure gold is out of 24 parts and is not a weight at all.
The quintal, and why Indian crop prices use it
A quintal is exactly 100 kilograms, so ten quintals make a tonne. In India it is the standard trading unit for grain: minimum support prices for wheat, paddy, pulses and sugarcane are announced in rupees per quintal, and mandi rates are quoted the same way. That makes quintal-to-kilogram and quintal-to-tonne the conversions most often needed when reading an Indian crop price.
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Units in this converter
| Unit | What it is |
|---|---|
| Kilogram (kg) | The kilogram is the SI base unit of mass — the unit almost every country weighs in. 1 kg = 1,000 grams. |
| Gram (g) | A gram is one thousandth of a kilogram — the everyday unit for food, spices and small parcels. |
| Milligram (mg) | A milligram is one thousandth of a gram. Medicine doses and vitamin labels are usually written in milligrams. |
| Microgram (µg) | A microgram is one thousandth of a milligram. Labels often write it as "mcg" because the µ symbol is easy to mistype. 1,000 mcg = 1 mg. |
| Tonne (t) | A tonne (metric ton) is exactly 1,000 kilograms — the unit used for freight, crops and vehicle loads. |
| Quintal (q) | A quintal is exactly 100 kilograms. It is the standard unit for crop prices in India — wheat, rice and sugarcane rates are quoted per quintal. |
| Pound (lb) | The pound is the main US and UK weight unit. Since 1959 it has been exactly 0.45359237 kilograms, so pound conversions are exact and not rounded. |
| Ounce (oz) | An ounce is one sixteenth of a pound (28.349523125 g exactly). This is the ounce used for food and post — gold uses the heavier troy ounce. |
| Stone (st) | A stone is exactly 14 pounds. Britain and Ireland still give body weight in stones and pounds. |
| Short ton (ton (US)) | A short ton is exactly 2,000 pounds — the "ton" used in the United States. It is lighter than both the tonne and the long ton. |
| Long ton (ton (UK)) | A long ton is exactly 2,240 pounds — the traditional British ton, still used for shipping. 1 long ton = 1.12 short tons. |
| Troy ounce (oz t) | A troy ounce is 480 grains (31.1034768 g exactly) — the unit gold, silver and platinum are priced in. It is about 10% heavier than a normal ounce. |
| Grain (gr) | A grain is exactly 1/7000 of a pound (64.79891 mg). It is the oldest English weight unit and is still used for bullets, arrows and some medicines. |
| Carat (ct) | A metric carat is exactly 200 milligrams — the weight unit for gemstones. Do not confuse it with karat, which measures gold purity, not weight. |