Weight Conversion Tool

Easily convert between metric and imperial weight units including kilograms, pounds, grams, ounces, stone, tons, and more. Get precise conversions for all your weight measurement needs.

Value

From Unit

To Unit

Notes:

Conversion results are rounded to 6 decimal places for precision.
The metric system (kilograms, grams, etc.) is used internationally as the standard system of measurement.
The imperial system (pounds, ounces, etc.) is primarily used in the United States and some other countries.
Stone is commonly used for body weight in the UK and Ireland.

Understanding Weight Measurements

Weight is a measure of the force of gravity acting on an object. Throughout history, different civilizations have developed various systems to measure weight. Today, we primarily use two systems: the metric system (used globally) and the imperial system (used mainly in the United States and a few other countries).

Weight Conversion Formulas

Converting between different units of weight requires specific formulas based on the relationship between units. Here are some common conversion formulas:

Metric Conversions:

1 kilogram (kg) = 1,000 grams (g)
1 gram (g) = 1,000 milligrams (mg)
1 metric ton (t) = 1,000 kilograms (kg)

Imperial Conversions:

1 pound (lb) = 16 ounces (oz)
1 stone (st) = 14 pounds (lb)
1 US ton (short ton) = 2,000 pounds (lb)
1 Imperial ton (long ton) = 2,240 pounds (lb)

Metric to Imperial Conversions:

1 kilogram (kg) = 2.20462 pounds (lb)
1 pound (lb) = 0.453592 kilograms (kg)
1 ounce (oz) = 28.3495 grams (g)
1 stone (st) = 6.35029 kilograms (kg)
1 metric ton (t) = 2204.62 pounds (lb)
1 metric ton (t) = 0.984207 Imperial tons (long tons)
1 metric ton (t) = 1.10231 US tons (short tons)

Common Weight Units Comparison

This table provides a comparison of different weight units to help visualize their relative sizes:

Unit	Symbol	System	Equivalent in Grams	Common Uses
Milligram	mg	Metric	0.001 g	Medicine, microscopic measurements
Gram	g	Metric	1 g	Food ingredients, small items
Ounce	oz	Imperial	28.35 g	Food portions, packaged goods in US
Pound	lb	Imperial	453.59 g	Body weight (US), medium-sized items
Kilogram	kg	Metric	1,000 g	Standard unit, body weight globally
Stone	st	Imperial	6,350.29 g	Body weight in UK and Ireland
Metric Ton	t	Metric	1,000,000 g	Heavy cargo, vehicles, large quantities
US Ton (Short)	ton	US	907,185 g	Freight and bulk materials in US
Imperial Ton (Long)	ton	Imperial	1,016,047 g	Shipping and trade in UK

History of Weight Measurements

Throughout history, humans have used various methods to measure weight:

Balance scales: Ancient civilizations used balance scales with standardized weights as early as 2400 BCE in Egypt.
Grain-based systems: Early units like the carat (derived from carob seeds) and grain were based on the weight of seeds.
Pound (libra): The Roman pound (libra) is the ancestor of modern pound units, with "lb" as its abbreviation.
Stone: Originally varied by location and commodity, now standardized at 14 pounds.

The metric system was developed during the French Revolution in the late 18th century to create a unified, decimal-based system of measurement. It defines the kilogram as its base unit of weight and uses consistent prefixes (kilo-, centi-, milli-, etc.) to indicate multiples and fractions.

Metric vs. Imperial Systems for Weight

Metric System

The metric system is based on units of 10, making conversions simple. The base unit for weight is the gram, with kilogram as the primary unit for everyday use.

Used by most countries globally
Easy decimal-based conversions
Scientifically precise definitions
Consistent prefixes across different types of measurements
1 kg of water = 1 liter in volume (at 4°C)

Imperial System

The imperial system has historical roots with less consistent ratios between units. Common weight units include ounces, pounds, and tons.

Primarily used in the United States
Based on traditional measurements
Non-decimal conversions between units
Different regional variations (US ton vs. Imperial ton)
Stone commonly used in UK for body weight

Practical Applications of Weight Conversion

Cooking and baking: Converting between grams and ounces for international recipes
Health and fitness: Converting body weight between kilograms, pounds, and stones
Shipping and logistics: Converting between pounds, kilograms, and tons for freight
Medicine: Converting between milligrams and other units for precise dosing
Science and education: Learning to work with different measurement systems
Commercial trade: Converting weights for international commerce and pricing
Manufacturing: Ensuring components meet weight specifications across different standards

Weight vs. Mass: Understanding the Difference

Although often used interchangeably in everyday conversation, weight and mass are different concepts:

Mass

Mass is a measure of the amount of matter in an object. It remains constant regardless of location. The SI unit of mass is the kilogram (kg).

Weight

Weight is the force exerted on an object due to gravity. It varies depending on gravitational field strength. The SI unit of weight (as a force) is the newton (N).

For practical purposes on Earth, weight and mass measurements are often treated as equivalent. However, an object's weight would be different on the Moon (about 1/6 of Earth) while its mass would remain the same.

Weight Converter