Calculator tool
How this calculator works
Use the explanation to understand the formula, assumptions, and practical limits behind the calculator result.
What This Calculator Does
This calculator converts mass between common units such as grams, kilograms, pounds, ounces, and stones. Mass tells you how much matter something contains.
Mass and Weight
In everyday life, people often say weight when they mean mass. In science, they are different: mass stays the same, while weight changes if gravity changes. Near Earth's surface, the everyday conversion still uses the familiar mass units people expect.
A Simple Example
Because 1 kilogram = 1,000 grams, a mass of 2.5 kg equals 2,500 g. The idea is straightforward, but the starting unit must be correct.
How to Avoid Mistakes
Check the input unit before converting, especially when moving between metric and customary units. Keep enough digits during the calculation, then round only the final result you plan to use.
Frequently asked questions
Is mass the same as weight?
Strictly speaking, no. Mass is the amount of matter, while weight is the force caused by gravity. In everyday use near Earth, people often use the words as if they mean the same thing.
How many grams are in a kilogram?
There are exactly 1,000 grams in 1 kilogram, so that metric conversion is exact.
Why should I delay rounding?
Rounding too early can slightly change later calculations. Keep more digits while working, then round the final displayed answer.
Why do stones appear in some weight conversions?
Stone is still commonly used for body weight in the UK and Ireland, where 1 stone = 14 pounds.
