Weight & Mass Converter

Convert any weight & mass unit to another with this free weight & mass converter. It supports 11 units including kilograms, grams, milligrams, micrograms, metric tons, pounds, and more. Pick a conversion below for a dedicated calculator, formula, and reference table. For example, 1 kg = 1000 g.

All weight & mass conversions

Kilogram → Gram Kilogram → Milligram Kilogram → Microgram Kilogram → Metric Ton Kilogram → Pound Kilogram → Ounce Kilogram → Stone Kilogram → US Ton Kilogram → Imperial Ton Kilogram → Carat Gram → Kilogram Gram → Milligram Gram → Microgram Gram → Metric Ton Gram → Pound Gram → Ounce Gram → Stone Gram → US Ton Gram → Imperial Ton Gram → Carat Milligram → Kilogram Milligram → Gram Milligram → Microgram Milligram → Metric Ton Milligram → Pound Milligram → Ounce Milligram → Stone Milligram → US Ton Milligram → Imperial Ton Milligram → Carat Microgram → Kilogram Microgram → Gram Microgram → Milligram Microgram → Metric Ton Microgram → Pound Microgram → Ounce Microgram → Stone Microgram → US Ton Microgram → Imperial Ton Microgram → Carat Metric Ton → Kilogram Metric Ton → Gram Metric Ton → Milligram Metric Ton → Microgram Metric Ton → Pound Metric Ton → Ounce Metric Ton → Stone Metric Ton → US Ton Metric Ton → Imperial Ton Metric Ton → Carat Pound → Kilogram Pound → Gram Pound → Milligram Pound → Microgram Pound → Metric Ton Pound → Ounce Pound → Stone Pound → US Ton Pound → Imperial Ton Pound → Carat Ounce → Kilogram Ounce → Gram Ounce → Milligram Ounce → Microgram Ounce → Metric Ton Ounce → Pound Ounce → Stone Ounce → US Ton Ounce → Imperial Ton Ounce → Carat Stone → Kilogram Stone → Gram Stone → Milligram Stone → Microgram Stone → Metric Ton Stone → Pound Stone → Ounce Stone → US Ton Stone → Imperial Ton Stone → Carat US Ton → Kilogram US Ton → Gram US Ton → Milligram US Ton → Microgram US Ton → Metric Ton US Ton → Pound US Ton → Ounce US Ton → Stone US Ton → Imperial Ton US Ton → Carat Imperial Ton → Kilogram Imperial Ton → Gram Imperial Ton → Milligram Imperial Ton → Microgram Imperial Ton → Metric Ton Imperial Ton → Pound Imperial Ton → Ounce Imperial Ton → Stone Imperial Ton → US Ton Imperial Ton → Carat Carat → Kilogram Carat → Gram Carat → Milligram Carat → Microgram Carat → Metric Ton Carat → Pound Carat → Ounce Carat → Stone Carat → US Ton Carat → Imperial Ton

About these units

Kilogram (kg)

Definition: The kilogram (kg) is the SI base unit of mass, defined since 2019 by fixing the value of the Planck constant.
History: It was originally the mass of one liter of water, then a platinum-iridium cylinder kept near Paris until the 2019 redefinition.
Current use: The kilogram is the global standard for weighing goods, people, and ingredients in science and commerce.

Gram (g)

Definition: A gram (g) is one thousandth of a kilogram, a small metric unit of mass used for light objects.
History: Defined in the 1790s as the mass of one cubic centimeter of water at its freezing point.
Current use: Grams are used for food portions, nutrition labels, postage, and laboratory work worldwide.

Milligram (mg)

Definition: A milligram (mg) is one thousandth of a gram, used for very small masses such as medication doses.
History: It is a standard metric subdivision using the prefix "milli-" (one thousandth).
Current use: Milligrams express drug dosages, vitamin content, and quantities in chemistry and pharmacology.

Microgram (µg)

Definition: A microgram (µg) is one millionth of a gram, used for trace amounts of substances.
History: It uses the SI prefix "micro-" (one millionth) and is sometimes written "mcg" on labels to avoid confusion.
Current use: Micrograms measure potent drugs, hormones, and micronutrients like vitamin B12 and folate.

Metric Ton (t)

Definition: A metric ton or tonne (t) equals 1,000 kilograms and is the metric unit for large masses.
History: It was adopted with the metric system as a convenient multiple of the kilogram.
Current use: Metric tons quantify cargo, industrial materials, vehicle weights, and carbon emissions.

Pound (lb)

Definition: A pound (lb) is an imperial unit of mass equal to exactly 0.45359237 kilograms, divided into 16 ounces.
History: Derived from the Roman "libra" (hence the abbreviation lb), it was standardised internationally in 1959.
Current use: Pounds are the everyday unit of body and food weight in the United States.

Ounce (oz)

Definition: An ounce (oz) is an imperial unit of mass equal to one sixteenth of a pound, about 28.35 grams.
History: It also descends from the Roman "uncia" (a twelfth) and was later fixed at 1/16 of the avoirdupois pound.
Current use: Ounces measure food portions, postal weights, and ingredients in the US and UK.

Stone (st)

Definition: A stone (st) is a British imperial unit of mass equal to 14 pounds, or about 6.35 kilograms.
History: Historically the stone varied by commodity before being fixed at 14 pounds in 1835.
Current use: Stones are still widely used in the UK and Ireland to express body weight.

US Ton (ton)

Definition: A US ton (short ton) equals 2,000 pounds, or about 907.18 kilograms.
History: It became the standard "ton" in the United States as the country adopted the avoirdupois pound.
Current use: Short tons measure freight, mining output, and bulk goods in the United States.

Imperial Ton (long ton)

Definition: An imperial ton (long ton) equals 2,240 pounds, or about 1,016 kilograms.
History: The long ton derives from 20 hundredweight of 112 pounds each in the British imperial system.
Current use: Long tons appear in UK shipping and in expressing the displacement of ships.

Carat (ct)

Definition: A carat (ct) is a unit of mass for gemstones equal to exactly 200 milligrams.
History: It takes its name from the carob seed, once used as a counterweight, and was standardised at 0.2 g in 1907.
Current use: Carats express the weight of diamonds and other precious stones in the jewellery trade.

Frequently asked questions

What weight & mass units can I convert?

This weight & mass converter supports 11 units: kilograms, grams, milligrams, micrograms, metric tons, pounds, ounces, stones, us tons, imperial tons, carats. Select any pair below to open a dedicated converter with a formula and conversion table.

How accurate is the weight & mass converter?

Conversions use exact definitional factors, so results are accurate to the precision you need for science, engineering, and everyday use. Values are rounded only for display.

Is the weight & mass converter free?

Yes. Every weight & mass conversion is completely free, needs no sign-up, and runs entirely in your browser — your inputs never leave your device.

Free, private, and instant — every conversion runs in your browser.

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