Weight Unit Converter – Check All 150 Units

Type a number in the Convert from field and choose its unit from the list below the field, then choose the unit you want below the Convert to field. The result appears as you type. It also works the other way round: type a number in the Convert to field and the converter fills in the first one.

Both lists hold the same 150 units in 28 groups. The most used units come first, followed by imperial and US customary units, troy and apothecaries' weights, gemstone units and biblical weights. After them come metric, engineering, astronomical and physics units, old units from Poland, Russia and the rest of Europe, Japanese, Chinese and Indian units, and ancient ones.

You don't have to look for the unit in the list. Type it after the number, for example “150 lbs”, “12 oz” or “3 tonnes”, and the converter sets the unit in the list below the field and tells you which one it picked. Plurals and abbreviations work, so “2 kilos”, “2 kg” and “2 kilograms” all set the kilogram.

Some names cover several units. If you type just “2 tons”, the converter takes the short ton of 2,000 pounds used in the US and notes below the field that there are other tons on the list. Hundredweights, drams, shekels and talents work the same way.

Many old units have no single agreed value, because the original standards are lost or the sources disagree. When you pick one of them, a line below the fields shows the value we calculate with and, where the sources differ, the range they give. The result then has only as many digits as the sources can support.

The Copy result button copies the number from the Convert to field, and Clear all empties both fields.

A pound is exactly 0.45359237 kg, so a kilogram is about 2.20462 pounds. NIST gives this value with a reference to the Federal Register notice of July 1, 1959[1], and the British Weights and Measures Act 1985 uses the same number. Under the act an ounce is a sixteenth of a pound and a stone is 14 pounds[2], so an ounce is exactly 28.349523125 g and a stone 6.35029318 kg.

To convert pounds to kilograms, multiply by 0.45359237, and to convert kilograms to pounds, divide by the same number. A body weight of 70 kg is about 154.32 lb, and a 50 lb checked bag is 22.6796185 kg. Single pairs with ready tables are in the pounds to kg converter, the kg to pounds converter and the ounces to grams converter.

Stones and pounds

In the UK and Ireland people still give their body weight in stones and pounds[3]. Of the larger old British units, only the stone survives in everyday use[1]. Type “11 st 6” and the converter reads it as 11 stone and 6 pounds, that is 160 pounds or 72.5747792 kg. The stone to kg converter has a table of whole stones.

The base unit of mass in the International System of Units (SI) is the kilogram. Since 2019 it has been defined by fixing the Planck constant at exactly 6.626 070 15 × 10⁻³⁴ J s. Before that, the kilogram was the mass of the international prototype, and the number in the new definition was chosen so that the kilogram stayed the same[4].

The kilogram is the only coherent SI unit whose name already contains a prefix, so multiples and submultiples of mass are formed from the gram: a millionth of a kilogram is a milligram, not a microkilogram[4]. The list has every unit from the quectogram to the quettagram, so a 500 mcg vitamin dose is 0.5 mg, and the field also reads “mcg” and “ug”.

The tonne is not an SI unit, but it's accepted for use with the SI and equals 1,000 kg. The CIPM adopted it in 1879, and some English-speaking countries call it the metric ton[4]. The field reads “t”, “tonne”, “metric ton” and the trade abbreviation “MT”, while “Mt” stays the megatonne. The British act also defines the quintal as 100 kilograms[2].

Not quite. Mass measures how much matter a body contains, while weight is the force that gravity puts on it. In everyday speech weight often means mass, and NIST recommends saying mass whenever mass is meant[1]. This converter works with mass, so it won't take forces in newtons or pounds-force.

A kilogram-force (kgf, also called the kilopond) is the weight of 1 kg under standard gravity of 9.806 65 m/s², exactly 9.806 65 N, and a kip is 1,000 pounds-force[5]. If you type “10 kgf” or “5 kip”, the field says it isn't a unit of mass or weight.

The British act builds the larger units from the pound: a quarter is 28 pounds, a hundredweight 112 pounds, a cental 100 pounds and a ton 2,240 pounds[2]. In the United States that ton is called the long ton, and the ordinary US ton, the short ton, is 2,000 pounds[1]. So the long ton (UK) is 1,016.0469088 kg, the short ton (US) is 907.18474 kg, and the metric ton is 1,000 kg.

In the United States and Canada the short ton is the one most commonly used, in Great Britain the long ton, and in metric countries the metric ton[1]. Ship displacement is traditionally given in long tons[6]. Hundredweights follow the same split: 112 pounds in the UK, 100 pounds in the US, where the short hundredweight is still used in selling livestock and some grains[7]. The abbreviation “cwt” sets the short hundredweight and notes below the field that the UK one is on the list too.

The slug is a unit of mass in the British imperial and US customary systems: it's the mass that one pound-force accelerates at one foot per second squared[8], about 14.5939 kg[5].

Jewelers, mints and pharmacists have their own units, and their ounce is heavier than the kitchen one. The troy ounce is 31.1034768 g[2], about 10% more than an ordinary ounce, and gold, silver and platinum prices are quoted per troy ounce. The troy pound has 12 troy ounces[1], and a pennyweight is 24 grains[2]. Britain abolished the troy pound on January 6, 1879 and kept only the troy ounce and its subdivisions, while in the US the troy pound is still legal but seldom used[1].

The apothecaries' system shares the troy ounce and divides it into 8 drachms of 3 scruples each[2]. That's why “1 drachm” in the field sets the dram (apothecaries'), while “1 dram” sets the avoirdupois dram, a sixteenth of an ordinary ounce, and notes that there are two.

Carats and points

The carat is 0.2 g. Its name goes back to the carob seed, and the carat was later standardized at 1/444 ounce and then 0.2 gram[1]. The United States adopted the metric carat on July 1, 1913 and the United Kingdom on April 1, 1914, and a carat divides into 100 points[9], so a 50-point diamond weighs half a carat. Pearls were also weighed in pearl grains of a quarter carat[10]. Karats of gold are a different thing: they give purity, not weight, so the field answers “18 karat” with a note that it isn't a unit of mass.

Grains

The grain is the oldest unit of mass and the smallest in the avoirdupois, troy and apothecaries' systems. It started as a grain of wheat or barley used to weigh silver and gold[1]. Today it's 64.79891 mg, because a pound is exactly 7,000 grains, and the troy ounce has 480 grains[1]. Grains are commonly used for the weight of bullets and propellant, and archers weigh arrows in them[10]. The field reads “gr” as the grain, and the grains to grams converter has a ready table.

Before the metric system each European country weighed in its own pounds. The Russian funt was 409.512 g, divided into 32 lots, 96 zolotniks and 9,216 doli[11], and a pood was 40 funts[12]. Russian kettlebells were traditionally measured in poods of about 16.38 kg[13], and a 16 kg kettlebell is one pood rounded to a whole kilogram[12]. The converter counts the pood as about 16.3805 kg.

In Germany the word Pfund still means half a kilogram in a shop: in 1854 the German Customs Union fixed the pound at exactly 500 grams[14]. A Zentner is 50 kg in Germany but 100 kg in Austria and Switzerland[15]. The old Vienna pound was about 560 g[14], and the Bohemian centner held 120 pounds of 0.513 kg, 61.6 kg in all[16]. Poland's old centner was 160 pounds, about 64.8 kg[17].

France weighed in the Paris livre of about 489.5 g, divided into 16 ounces[18]. In Spain an arroba was 25 Castilian pounds, about 11.5 kg, while in Colombia half a kilogram is called a libra, which makes the arroba 12.5 kg there[19]. Portugal and Brazil rounded the arroba to 15 kg[20], and Brazil still weighs cattle in it[19]. Venice used two pounds, a light libbra sottile and a heavy libbra grossa, each divided into 12 ounces[21].

The tola is 180 grains, 11.6638038 g. It was the base of the British Indian weights and the standard measure for gold and silver bullion, and although India replaced it with metric units in 1956, gold bars are still sold in tolas in Bangladesh, India, Nepal, Pakistan and Singapore, most often as ten-tola bars[22]. The seer and the maund were larger Indian trade units built on the tola.

In Hong Kong the catty is 604.78982 g and the tael is a sixteenth of it[23], about 37.8 g. In China the jin has been half a kilogram since 1929, when it held 16 liang[24], and in 1959 the government of the People's Republic ordered it to be divided into 10 liang[25], so a liang is now 50 g.

Japan's Weights and Measures Act of 1891 set the kan at 3.75 kg, exactly 1,000 momme[26]. A momme is therefore 3.75 g, and it's still a recognized unit in the international pearl trade[27].

Astronomers often give the mass of planets and stars in Earth masses, Jupiter masses or solar masses. According to NASA the Earth is 5.9722 × 10²⁴ kg, the Moon 7.346 × 10²² kg and the Sun 1.9884 × 10³⁰ kg[28]. That makes the Sun about 332,943 Earth masses and Jupiter about 317.8.

At the other end of the scale is the dalton (atomic mass unit), a twelfth of the mass of a carbon-12 atom. The dalton (Da) and the unified atomic mass unit (u) are two names for the same unit, 1.66053906892 × 10⁻²⁷ kg[4], and the field also reads “amu”. The list also has the electron, proton and neutron masses from CODATA 2022[29].

The Babylonians and Sumerians had 60 shekels in a mina and 60 minas in a talent, and the pound derives from the mina of ancient civilizations[1]. The Roman pound (libra) was divided into 12 ounces[1], and the converter counts it as about 329 g[30]. The Attic drachma, a hundredth of the Attic mina, is about 4.31 g[31]. Egypt weighed in debens, about 13.6 g in the Old and Middle Kingdoms and about 91 g in the New Kingdom[32].

The shekel is the basic unit of weight in the Bible. Stone weights found by archaeologists average about 11.3 g, with a spread of 11–13 g[33]. Exodus calls the shekel twenty gerahs and the half shekel a bekah (Exodus 30:13; 38:26)[34]. The converter counts the biblical shekel as about 11.3 g and shows the range from the sources below the fields.

A talent was 3,000 shekels, about 34 kg[33]. Exodus shows the ratio: the silver from 603,550 men at half a shekel each came to a hundred talents and 1,775 shekels (Exodus 38:25–26)[34], and the NIV footnote puts the hundred talents at about 3.4 metric tons[35]. The 666 talents of gold Solomon received each year (1 Kings 10:14) are about 22.6 t in the converter, and Absalom's hair, cut once a year, weighed 200 shekels (2 Samuel 14:26), about 2.26 kg[35].

The mina was 50 shekels in Palestine, about 565 g, and 60 shekels in Babylonia[33]. Ezekiel 45:12 adds up “twenty shekels, five and twenty shekels, fifteen shekels” to a maneh, which is 60[34], and the NIV footnote notes that the common mina was 50 shekels[35]. The converter counts the biblical mina (maneh) as 50 shekels, about 565 g.