Understanding Weight and Mass

In physics, weight is defined as the force exerted on an object due to gravity, calculated as the product of mass and gravitational acceleration. Mass, on the other hand, is a measure of the amount of matter in an object and remains constant regardless of location. While weight can vary depending on gravitational pull, mass is invariant. Despite this distinction, in everyday language, the terms 'weight' and 'mass' are often used interchangeably.

Unit Systems for Measuring Weight


  • International System of Units (SI): The SI system is globally recognized and includes units such as the kilogram (kg), gram (g), and decagram (dag).
  • Imperial System: Predominantly used in the United States and a few other countries, this system features units like the pound (lb) and ounce (oz).

Weight unit conversion calculator

Metric tons

Stones

If you want to learn more about the stone unit, please read our article: Stone calculator

Conversion factors

Pounds

Want to learn more about the pound unit? Read our guide: Pound - what is this unit?

Conversion factors


Ounces

For more information about ounces, check out our article: Ounce conversion calculator

Conversion factors


Grams

All the most important information about the gram mass unit can be found in our guide: Gram - what unit is this?

Conversion factors:


Kilograms

Read the history and full definition in our article: Kilogram - what unit is this?

Conversion factors:


What are the world's weight units?

Weight (mass) units vary across the world based on region, tradition, and standardization systems. Below is a breakdown by continent and country:

North America

South America

Europe

Africa

Asia

Australia and Oceania

The metric system (kg, g, t) is used in most of the world, but the Imperial system (lb, oz, st, ton) remains in the U.S. and parts of the UK.

News in the guide

12 Apr, 2025 / By Sizees
Stone calculator
03 Apr, 2025 / By Sizees
Ounce conversion calculator
01 Apr, 2025 / By Sizees
Kilogram - what unit is this?