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.
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.