Mass Converter - Weight & Mass Unit Converter

Metric Units: Kilograms, Grams, Milligrams, Micrograms, Metric Tons

The metric system is the international standard for mass measurement. The base unit is the kilogram (kg), the only SI base unit with a prefix. Historically, the kilogram was defined by a physical prototype (a platinum‑iridium cylinder), but since 2019 it is defined by the Planck constant. Metric mass units are decimal‑based: 1 kg = 1000 g, 1 g = 1000 mg, 1 mg = 1000 μg, and 1 metric ton (t) = 1000 kg. This simplicity makes conversions easy: to convert kg to g, multiply by 1000; to convert g to kg, divide by 1000.

Practical examples: A typical human weighs 70–80 kg. A bag of flour is 1 kg (2.2 lb). A paperclip weighs about 1 gram. A grain of salt is about 0.5 mg. A small car weighs about 1 metric ton (1000 kg). The metric system is used for scientific, medical, and most international trade purposes.

Imperial Units: Pounds, Ounces, Stones, US/UK Tons

The imperial system (US customary units) is still the primary system for everyday mass measurements in the United States and partially in the UK and Canada. Conversions are non‑decimal: 1 pound (lb) = 16 ounces (oz), 1 stone (st) = 14 lb, 1 US ton = 2000 lb, 1 UK ton = 2240 lb. This makes manual conversion more complex, so a lbs to kg converter or stones to kg calculator is essential for international communication.

Common examples: A typical adult weighs 150–200 lb (11–14 stones). A loaf of bread weighs about 1 lb. A letter weighs around 1 oz. A large SUV weighs about 2.5 US tons. Our tool makes it easy to convert kg to lbs (multiply by 2.20462), convert lbs to kg (multiply by 0.453592), and convert stones to kg (multiply by 6.35029).

Troy Units: Troy Ounces and Grains - Precious Metals

The troy weight system is used almost exclusively for precious metals (gold, silver, platinum, palladium) and gemstones. A troy ounce (oz t) is heavier than a standard ounce: 1 troy ounce = 31.1034768 grams, compared to 28.3495 grams for a standard ounce. A grain (gr) is the same in both troy and avoirdupois systems: 1 grain = 64.79891 mg. There are 480 grains in a troy ounce and 437.5 grains in a standard ounce. When buying or selling gold, silver, or other precious metals, prices are quoted per troy ounce. Our troy ounce converter helps you convert between oz t, grams, and standard ounces accurately.

Carats: Precious Gemstones

A carat (ct) is the standard unit of mass for gemstones (diamonds, rubies, sapphires, etc.). One carat equals exactly 200 milligrams (0.2 grams). Carats are further divided into 100 points, so a 0.25 ct diamond is also called a 25‑point diamond. The carat weight of a gemstone is the single most important factor in its price, though cut, colour, and clarity also matter. To convert carats to grams, multiply by 0.2. To convert grams to carats, multiply by 5. Our converter handles this seamlessly.

Atomic Mass Units: Molecular and Atomic Scales

The atomic mass unit (u), also called a dalton (Da), is a unit used to express atomic and molecular masses. It is defined as 1/12 of the mass of a carbon‑12 atom. 1 u ≈ 1.660539 × 10⁻²⁷ kg. While unimaginably small, this unit is essential in chemistry and physics for calculating molar masses, molecular weights, and isotopic abundances. Our converter includes u for scientific users.

How do I convert kilograms to pounds?

To convert kg to lbs, multiply the kilogram value by 2.20462. For example, 5 kg × 2.20462 = 11.0231 lb. Conversely, to convert lbs to kg, divide by 2.20462 or multiply by 0.453592. Our tool does this instantly.

How many grams are in an ounce?

One standard ounce (avoirdupois) equals exactly 28.349523125 grams. For practical purposes, 1 oz ≈ 28.35 g. To convert ounces to grams, multiply by 28.3495. To convert grams to ounces, divide by 28.3495.

What is the difference between a US ton and a UK ton?

A US short ton equals 2000 pounds (907.185 kg). A UK long ton equals 2240 pounds (1016.047 kg). The metric ton (tonne) equals 1000 kg (2204.62 lb). Our converter includes all three.

How accurate is this mass converter?

Our converter uses exact conversion factors based on international standards (e.g., 1 lb = 0.45359237 kg exactly). It displays results to 6 decimal places, providing excellent precision for cooking, shipping, science, and jewelry.

Can I use this weight converter offline?

Yes. Once the page has loaded, all conversion logic runs locally in your browser. No internet connection is required, making it reliable anywhere - in the kitchen, at the gym, or at the jewellery store.

What is a troy ounce and why is it different?

A troy ounce (oz t) is used for precious metals like gold and silver. It weighs 31.1034768 grams, whereas a standard (avoirdupois) ounce weighs 28.3495 grams. Gold prices are always quoted per troy ounce. Our converter handles troy ounces and standard ounces separately to avoid costly mistakes.

How many carats in a gram?

One carat equals 0.2 grams, so there are 5 carats per gram. To convert carats to grams, multiply by 0.2. To convert grams to carats, multiply by 5. Diamond weights are always expressed in carats (e.g., a 1 carat diamond weighs 0.2 g).