Weight Conversion
Weight measures the force exerted by gravity on an object's mass. It is crucial in science, engineering, commerce, and daily activities like cooking and shipping. Weight units fall into two main systems: metric, based on grams and kilograms, and imperial, including pounds and ounces. Accurate weight measurement ensures consistency in trade, health, and scientific experiments.
Kilograms (kg)
Grams (g)
Milligrams (mg)
Micrograms (µg)
Metric Tons (t)
Pounds (lb)
Ounces (oz)
Stone (st)
US Tons (Short Tons) (US t)
Imperial Tons (Long Tons) (imp t)
Carats (ct)
Troy Ounces (oz t)
Troy Pounds (lb t)
Grains (gr)
Pennyweights (dwt)
Hundredweights (US) (US cwt)
Hundredweights (Imperial) (imp cwt)
Slugs (slug)
Atomic Mass Units (u)
Unit Descriptions
- Kilograms
- The base SI unit of mass equal to 1,000 grams, used worldwide for most weight measurements.
- Grams
- A metric unit of mass, defined as one-thousandth of a kilogram, common in everyday and scientific use.
- Milligrams
- One-thousandth of a gram, used for precise measurements in medicine and chemistry.
- Micrograms
- One-millionth of a gram, essential for measuring extremely small masses like contaminants or nutrients.
- Metric Tons
- Also called tonnes, equal to 1,000 kilograms, used globally for large mass measurements.
- Pounds
- An imperial unit equal to 0.453592 kilograms, commonly used in the US and UK for body weight and goods.
- Ounces
- An imperial unit equal to 1/16 of a pound or 28.3495 grams, used for smaller weights in cooking and postal services.
- Stone
- An imperial unit equal to 14 pounds, mainly used in the UK for expressing human body weight.
- US Tons (Short Tons)
- Also called short tons, equal to 2,000 pounds or about 907.1847 kilograms, used in the United States.
- Imperial Tons (Long Tons)
- Also called long tons, equal to 2,240 pounds or about 1,016.0469 kilograms, used in the UK and some Commonwealth countries.
- Carats
- A unit of mass for gemstones equal to 200 milligrams, critical in jewelry and gem trade.
- Troy Ounces
- Used for precious metals, equal to approximately 31.1035 grams, distinct from avoirdupois ounces.
- Troy Pounds
- Comprised of 12 troy ounces, used in precious metal markets; one troy pound equals about 373.2417 grams.
- Grains
- A small imperial unit equal to 64.79891 milligrams, traditionally used in measuring bullets and medicine.
- Pennyweights
- Equal to 24 grains or about 1.555 grams, used mainly for weighing precious metals.
- Hundredweights (US)
- Also known as the short hundredweight, equal to 100 pounds, used in the US for bulk goods.
- Hundredweights (Imperial)
- Also called the long hundredweight, equal to 112 pounds, used in the UK and Commonwealth.
- Slugs
- An imperial unit of mass equal to about 14.5939 kilograms, used in physics to relate mass and force.
- Atomic Mass Units
- A unit for atomic-scale masses, defined as one twelfth of the mass of a carbon-12 atom.
FAQ
What is the difference between weight and mass?
Mass is the amount of matter in an object, measured in kilograms or grams. Weight is the force gravity applies on that mass, varying with location. Weight is measured in newtons in physics but commonly expressed in kilograms or pounds in everyday use.
How does gravity affect weight measurement?
Weight depends directly on gravitational acceleration, which varies slightly over Earth’s surface. Objects weigh less at higher altitudes or on the Moon. Scales calibrated for Earth gravity measure weight as mass times standard gravity 9.80665 m/s².
Why do metric and imperial systems use different weight units?
The metric system uses grams and kilograms based on the International System of Units (SI) for universal standardization. The imperial system evolved historically in English-speaking countries using pounds and ounces. Both systems coexist depending on regional preferences and applications.
What is a metric ton compared to a US ton?
A metric ton (tonne) equals exactly 1,000 kilograms. A US ton (short ton) equals 2,000 pounds or about 907.1847 kilograms. The metric ton is widely used internationally, while the US ton is common in the United States.
How are carats used in weight measurement?
Carats measure the weight of gemstones and pearls, with one carat equal to 200 milligrams. This unit provides precision necessary for valuing precious stones in jewelry and trade.
What are troy ounces and where are they used?
Troy ounces are units for precious metals, equal to approximately 31.1035 grams. This system differs from the avoirdupois ounce and is standard in trading gold, silver, platinum, and other precious metals.
What is a slug in weight measurement?
A slug is an imperial unit of mass used in the US, equal to about 14.5939 kilograms. It represents the mass that accelerates by 1 ft/s² when a force of one pound-force is applied.
Why do weight measurements sometimes vary in everyday settings?
Variations arise from using different units, calibration differences in scales, or environmental factors affecting gravity. Using standardized units and calibrated instruments reduces these discrepancies.
What is the atomic mass unit used for?
The atomic mass unit (amu) measures mass at the atomic scale, defined as one twelfth of the mass of a carbon-12 atom. It is essential in chemistry and physics for expressing atomic and molecular masses.
How do grains and pennyweights relate to each other?
Both are traditional units in the imperial system; one pennyweight equals 24 grains. These units are often used in measuring precious metals and pharmaceuticals.