Weight Converter

Convert between different weight units.

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Quick Conversions

What Is Weight Conversion?

Weight conversion is the process of translating a measurement of mass or weight from one unit to another. Different measurement systems have evolved around the world, and professionals in fields from medicine to shipping routinely need to switch between them. The three major systems relevant to weight are the metric system, the US customary system, and the British imperial system.

The metric system uses the gram as its fundamental unit of mass, with kilograms (thousands of grams) and metric tons (millions of grams) being the most frequently used practical units. The US customary system centers on the pound and ounce, while British imperial measurements add the stone as a commonly used unit for body weight. Each system also includes specialized units like grains, hundredweight, and various definitions of the ton that serve specific commercial and technical purposes.

How Weight Conversion Works

This converter uses the gram as its base unit for all calculations. Each supported weight unit has a defined conversion factor representing how many grams it equals. To convert between any two units, the tool first multiplies the input value by the source unit's gram factor to obtain grams, then divides by the target unit's gram factor to produce the result.

For example, to convert 5 pounds to kilograms: 5 pounds multiplied by 453.592 grams per pound gives 2,267.96 grams. Then 2,267.96 grams divided by 1,000 grams per kilogram gives 2.268 kilograms. This approach through a common base unit ensures every pairwise conversion is mathematically consistent.

The conversion factors used are based on international standard definitions. The international pound is defined as exactly 0.45359237 kilograms, and all other imperial and US customary weight units derive from this definition. Metric units follow strict decimal relationships: 1 kilogram equals exactly 1,000 grams, and 1 metric ton equals exactly 1,000 kilograms.

How to Use This Calculator

Enter a weight value in the input field on the left. Any positive number is accepted, including decimals for fractional amounts.
Select the source unit from the dropdown below the input. Units are grouped into Metric, Imperial/US, and Imperial/UK categories for easy navigation.
Select the target unit from the dropdown on the right. The converted result appears immediately in the output box.
Use the swap button between the two unit selectors to reverse the direction of conversion instantly without retyping the number.
Use the quick conversion buttons to load common starting values: 1 Kilogram, 1 Pound, 1 Ounce, or 1 Stone. Each button sets the corresponding value and unit as the input.
Review the all-conversions table below the main result for a comprehensive view of your input weight in every supported unit.

Common Conversions

Metric to Imperial

From	To	Factor
1 kilogram	2.20462 pounds	kg x 2.20462
1 gram	0.03527 ounces	g x 0.03527
1 metric ton	2,204.62 pounds	t x 2,204.62
1 kilogram	35.274 ounces	kg x 35.274

Imperial to Metric

From	To	Factor
1 pound	0.45359 kilograms	lbs x 0.45359
1 ounce	28.3495 grams	oz x 28.3495
1 stone	6.35029 kilograms	st x 6.35029
1 US ton	907.185 kilograms	US ton x 907.185

Within Imperial

From	To	Factor
1 pound	16 ounces	lbs x 16
1 stone	14 pounds	st x 14
1 US ton	2,000 pounds	US ton x 2,000
1 UK ton	2,240 pounds	UK ton x 2,240

Practical Examples

Example 1: Luggage Weight

Your airline allows 23 kilograms per checked bag. Your suitcase weighs 48 pounds on a bathroom scale. Convert: 48 pounds times 0.4536 equals 21.77 kilograms. You are under the limit with about 1.23 kilograms to spare.

Example 2: Cooking Measurement

A British recipe calls for 8 ounces of flour. To measure on a metric kitchen scale: 8 ounces times 28.35 equals 226.8 grams. Round to 227 grams for practical measuring.

Example 3: Body Weight

You weigh 75 kilograms and want to express this in stones and pounds for a British friend. Convert: 75 kilograms divided by 6.35029 equals 11.81 stones, which is 11 stone 11.3 pounds (0.81 times 14 equals 11.3 pounds).

Example 4: Shipping

A freight shipment weighs 4.5 metric tons. For a US shipping document: 4.5 times 2,204.62 equals 9,920.8 pounds, or 4.96 US tons.

Tips and Common Mistakes

Always specify which type of ton you mean. The metric ton, US ton (short ton), and UK ton (long ton) are all different. In international trade, specifying "metric tons" or "tonnes" removes ambiguity.

Do not confuse avoirdupois and troy ounces. The standard ounce used in this converter is the avoirdupois ounce at 28.35 grams. Precious metals use the troy ounce at 31.10 grams. Using the wrong ounce type when buying or selling gold, silver, or platinum results in a roughly 10 percent error.

Be precise with medication dosages. When converting milligrams to other units for medical purposes, even small rounding errors can matter. Always use the exact conversion rather than rough approximations, and verify dosages with a healthcare professional.

Remember that 1 kilogram does not equal 1 pound. This seems obvious, but in casual conversation the two units are sometimes loosely equated. A kilogram is approximately 2.2 times heavier than a pound, so confusing them leads to a large error.

Use the all-conversions table when working with multiple unit systems. Entering a value once and reading off all equivalents prevents the rounding errors that can accumulate when chaining multiple individual conversions together.

Frequently Asked Questions

How do I convert kilograms to pounds?

Multiply the kilogram value by 2.20462 to get pounds. For example, 70 kilograms equals 70 times 2.20462, which is 154.32 pounds. The conversion factor is based on the international pound being defined as exactly 0.45359237 kilograms. Our converter performs this calculation automatically and displays the result rounded to a practical number of decimal places.

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

A US ton, also called a short ton, equals 2,000 pounds or approximately 907.185 kilograms. A UK ton, also called a long ton, equals 2,240 pounds or approximately 1,016.047 kilograms. The UK ton is about 12 percent heavier. A metric ton equals 1,000 kilograms or 2,204.62 pounds. Confusion between these three types of tons can lead to significant measurement errors in commerce and shipping.

How many grams are in an ounce?

One ounce (avoirdupois) equals approximately 28.3495 grams. This is the standard ounce used for most everyday weighing in the United States. Note that a troy ounce, used for precious metals, equals approximately 31.1035 grams. When converting between ounces and grams, always confirm which type of ounce is relevant to your context to avoid errors.

What is a stone and where is it used?

A stone equals 14 pounds or approximately 6.35 kilograms. It is used primarily in the United Kingdom and Ireland for measuring body weight. For example, a person weighing 150 pounds would be described as 10 stone 10 pounds in British English. The stone is not commonly used in the United States, where body weight is typically stated in pounds only.

How do I convert milligrams to grams?

Divide the milligram value by 1,000 to get grams. For example, 500 milligrams equals 0.5 grams. This conversion follows the metric system where the prefix milli means one-thousandth. Milligrams are commonly used for medication dosages, nutritional supplement amounts, and chemical measurements where quantities are very small relative to a full gram.

What is a grain and when would I use it?

A grain equals approximately 0.0648 grams or 64.8 milligrams. It is one of the oldest units of weight measurement, originally based on the weight of a single grain of barley. Today it is used primarily in ballistics to measure bullet and propellant weights, in pharmacy for certain traditional dosage measurements, and in precious metal weighing alongside troy ounces.

How do I convert between metric tons and US tons?

To convert metric tons to US tons, multiply by 1.10231. To convert US tons to metric tons, multiply by 0.907185. For example, 5 metric tons equals 5.512 US tons. The difference is about 10 percent, which can be significant in industrial shipping and trade. Always specify which type of ton you mean in contracts and documentation to avoid costly misunderstandings.

Is weight the same as mass?

Technically, mass and weight are different physical concepts. Mass measures the amount of matter in an object and is constant regardless of location. Weight measures the gravitational force acting on an object and varies depending on the strength of gravity. However, in everyday usage and in this converter, the terms are used interchangeably because all measurements are assumed to be taken at standard Earth gravity.