Conversions

Weight & Mass Converter

What this does

Convert weights between milligrams, grams, kilograms, tonnes, ounces, pounds, stone and US tons using exact internationally agreed factors.

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Calculator inputs

How to use it

Using the weight & mass converter

  1. 01

    Enter the weight

    Any positive number works, from milligram recipes to tonne freight.

  2. 02

    Set the units

    Pick the source unit and the target unit from the dropdowns.

  3. 03

    Compare common units

    Alongside your conversion, see grams, kilograms, ounces and pounds equivalents.

Good to know

Pounds, stone and kilos

Britons quote body weight in stone (14 lb), Americans in pounds, and most of the world in kilograms. One stone is 6.35029318 kg; knowing your own weight in all three makes international conversations instant.

Mass versus weight

Strictly, kilograms measure mass while pounds-force measure weight under gravity. Everyday converters treat them interchangeably at Earth’s surface, where the distinction never changes a recipe or a shipping quote.

Cooking across borders

Recipes mix ounces with grams constantly. Since one ounce is exactly 28.349523125 g, converting a 12 oz bag of chocolate gives about 340 g; which is exactly what European packaging prints.

How it's calculated

The math behind this calculator

result = value × factor(from) ÷ factor(to) Exact anchors: 1 lb = 0.45359237 kg, 1 oz = 28.349523125 g

Each amount converts to kilograms using internationally agreed exact constants; the 1959 agreement fixes the pound at 0.45359237 kg and the ounce at one sixteenth of that; then divides by the destination unit’s factor.

Assumptions & limitations

  • Results are rounded only for display; full precision is used internally.
  • Conversions use exact standard definitions of each unit.

Worked example

A 10 lb bag of flour weighs about 4.536 kg on a metric scale.

FAQ

Frequently asked questions

Is a UK long ton included?
No; the “US ton” here is the short ton of 2,000 lb (907.18474 kg). The 2,240 lb long ton survives mostly in UK shipping history.
How do I convert stone to pounds quickly?
Multiply stone by 14 mentally, or use the tool: 11 st equals 154 lb exactly.
Are carats or troy ounces supported?
Not in this tool; those are gemstone and precious-metal units with different definitions from ordinary avoirdupois ounces.

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