Mass Converter
Convert units of mass like kilograms, pounds, ounces, grams, stone, and more.
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Base Unit
Relative Value
*Diagram shows values relative to the selected base unit (Kilogram).
Unit Information
What are Kilograms (kg)?
The kilogram (symbol: kg) is the base unit of mass in the International System of Units (SI). It is widely used across the globe for nearly all applications requiring mass measurement. It is now defined based on fixed numerical values of fundamental physical constants, specifically the Planck constant.
What are Grams (g)?
A gram (symbol: g) is a metric unit of mass equal to one thousandth of a kilogram. It is a very common unit for everyday measurements, such as food ingredients in cooking or the weight of small items.
What are Milligrams (mg)?
Milligrams (one-thousandth of a gram) are very small units of mass used extensively in medicine, pharmaceuticals, and chemistry for measuring dosages and minute quantities of substances.
What are Micrograms (µg)?
Micrograms (one-millionth of a gram) are extremely small units of mass used in pharmacology, toxicology, and analytical chemistry for measuring trace amounts of substances.
What are Pounds (lb)?
The pound (symbol: lb, or sometimes #) is a unit of mass used in the imperial and United States customary systems. The internationally recognized avoirdupois pound is legally defined as exactly 0.45359237 kilograms. One pound is divided into 16 avoirdupois ounces.
What are Ounces (oz)?
The ounce (symbol: oz) is an imperial and US customary unit of mass. One ounce is 1/16th of a pound. It is commonly used for measuring food products, postal items, and is also used for the weight of precious metals (as the troy ounce, which is slightly different).
What is a Stone (st)?
The stone (symbol: st) is an imperial unit of mass equal to 14 pounds (approximately 6.35 kg). It is still commonly used in the UK and Ireland for measuring human body weight.
What are Carats (ct)?
A carat (symbol: ct) is a unit of mass used for measuring gemstones and pearls. One carat is defined as exactly 200 milligrams (0.2 grams). It should not be confused with 'karat', which is a measure of gold purity.
What is a Metric Ton (Tonne)?
A metric ton, also known as a tonne (symbol: t), is a unit of mass equal to 1,000 kilograms or approximately 2,204.6 pounds. It is commonly used for measuring large quantities, such as the weight of vehicles, cargo, and industrial materials.
Formulas
1 kg ≈ 2.20462 lb
To convert kilograms to pounds, multiply by approximately 2.20462.
1 lb = 0.45359237 kg
To convert pounds to kilograms, multiply by 0.45359237.
1 stone = 14 lb
One stone is defined as exactly 14 pounds.
1 ounce = 1/16 lb
One ounce is defined as one-sixteenth of a pound.
1 kg = 1000 g
One kilogram is equal to one thousand grams.
1 carat = 0.2 g
One carat is defined as 0.2 grams.
Key Reference Points
- A liter of water has a mass of approximately 1 kilogram (or about 2.2 pounds).
- An average adult male might weigh around 70-90 kilograms (or 154-198 pounds).
- A standard pineapple typically weighs between 1 and 2 kilograms (2 to 4.5 pounds).
- A US nickel coin weighs exactly 5 grams.
- A standard chicken egg has a mass of about 50-60 grams.
- A small car typically has a mass of 1,000 to 1,500 kilograms.
- A large African elephant can have a mass of over 6,000 kilograms (6 metric tons).
- The Eiffel Tower has a mass of about 7,300 metric tons.
- A standard 20-foot shipping container can hold up to about 28 metric tons of cargo.
- The Space Shuttle Orbiter had a mass of about 78,000 kilograms when empty.
Did You Know?
The 'stone' (st) is a unit of mass still commonly used in the UK and Ireland for measuring human body weight. One stone is equal to 14 pounds (approximately 6.35 kg). Its use dates back to historical trade where stones were used as standard weights.
An object's mass remains the same on the Moon as on Earth, but its weight would be about 1/6th because the Moon's gravitational pull is weaker. This highlights the difference between mass (amount of matter) and weight (force due to gravity).
The modern definition of the kilogram is based on a fixed numerical value of the Planck constant, a fundamental constant in quantum mechanics. This provides a more stable and universal definition than a physical artifact.
The 'grain' is one of the oldest units of mass, originally based on the mass of a single grain of cereal. It is still used today in some fields, such as for measuring the mass of bullets and the dosage of some pharmaceuticals. 1 gram is approximately 15.4 grains.
The Earth has a mass of approximately 5.97 x 10²⁴ kilograms. This immense mass is what creates the gravitational field that keeps us on the ground.
At the atomic level, kilograms are too large. Scientists use the atomic mass unit (amu) or Dalton (Da). One amu is defined as 1/12th the mass of a carbon-12 atom. It's approximately 1.66 x 10⁻²⁷ kg.
The troy ounce is a unit of mass used for precious metals like gold and silver. It is slightly heavier than the standard (avoirdupois) ounce, weighing about 31.1 grams compared to 28.35 grams.
The blue whale is the most massive animal on Earth, with adults reaching up to 190 metric tons (190,000 kilograms or about 420,000 pounds).
In some engineering systems, the 'slug' is a unit of mass. It's defined as the mass that accelerates by 1 ft/s² when a force of one pound-force is exerted on it. One slug is approximately 14.6 kg.
Density is the mass of a substance per unit volume (e.g., kg/m³). Osmium is one of the densest elements, meaning a small volume of it is surprisingly heavy.
By a convenient near-coincidence, one liter of water has a mass of almost exactly one kilogram at its temperature of maximum density (4 °C).
In addition to the metric ton (1000 kg), there's the 'short ton' (common in the US), which is 2000 lbs (about 907 kg), and the 'long ton' (used in the UK), which is 2240 lbs (about 1016 kg).
Einstein's famous equation reveals that mass and energy are equivalent. This means mass can be converted into energy, a principle that powers nuclear reactors and stars.
The carat, used for gemstones, originated from the carob seed. These seeds were historically used as a standard for weight due to their perceived uniform mass.
Inertial mass is an object's resistance to acceleration (from F=ma), while gravitational mass determines the strength of the gravitational force it exerts. Einstein's principle of equivalence states that these two masses are identical.
The dram is an old unit of mass, part of both the apothecaries' and avoirdupois systems. In the avoirdupois system, 16 drams make an ounce.
Although an astronaut is 'weightless' in orbit, they still have the same mass. This means a significant force is still required to accelerate or decelerate them.
The mass of the Earth was first accurately determined by Henry Cavendish in 1798. He used a torsion balance to measure the gravitational attraction between lead spheres, allowing him to calculate Earth's density and mass.