Weight / Mass Converter
Convert between grams, kilograms, pounds, ounces, stones, and tons instantly.
About the Weight Converter
The Weight / Mass Converter turns any weight or mass into another unit instantly — milligrams, grams, kilograms, tonnes (metric tons), ounces, pounds, stones, and US (short) tons. Type a number, pick the unit you have and the unit you want, and the answer appears immediately. All the math runs in your browser, so it's instant and works offline once the page has loaded.
Weight conversions come up constantly: following a recipe written for another country, weighing luggage against an airline limit, tracking body weight in stones or pounds, buying produce priced by the kilo, or shipping a parcel quoted in ounces. This tool removes the mental arithmetic and the risk of using the wrong factor, whether you're switching between the metric and imperial/US systems or just moving between grams and kilograms.
How to use
- Enter a value in the "From" box.
- Choose the unit you're converting from in the first dropdown.
- Choose the unit you want in the second dropdown — the result updates as you type.
- Use the ⇄ swap button to reverse the direction (for example, switch from "kilograms → pounds" to "pounds → kilograms") without re-entering anything.
Every conversion uses exact, internationally standardized factors relative to the gram — for instance, 1 ounce is exactly 28.349523125 grams, 1 pound is exactly 453.59237 grams, and 1 stone is exactly 6,350.29318 grams — so the results are accurate for cooking, shipping, schoolwork, and everyday use alike. Results are shown with enough significant figures to stay precise without cluttering the display.
Common conversions
- 1 kilogram = 2.20462 pounds
- 1 pound = 453.592 grams
- 1 ounce = 28.3495 grams
- 1 stone = 6.35029 kilograms
- 1 tonne = 1,000 kilograms
- 1 US ton = 907.185 kilograms
Frequently asked questions
How accurate are the conversions?
Very accurate. Every unit is defined relative to the gram using its exact international factor, so conversions are correct to eight significant figures — more than enough for cooking, shipping, science, and school. The only rounding is in how the final result is displayed.
Does this work without an internet connection?
Once the page has loaded, yes. All the calculations happen locally in your browser with no server involved, so conversions keep working even if you go offline.
What's the difference between weight and mass?
In everyday use the two terms are used interchangeably, and that's how this tool treats them: a kilogram and a pound both describe an amount of matter (mass). Strictly, weight is the force gravity exerts on that mass, but for kitchen scales, shipping, and daily life the practical answer is the same, so you can convert freely between all the listed units.
What is a stone and where is it used?
A stone equals exactly 14 pounds, or about 6.35 kilograms. It's still widely used in the UK and Ireland to describe body weight — someone might say they weigh "11 stone" rather than 154 pounds or 70 kilograms. This converter handles it directly.
What's the difference between a metric tonne and a US ton?
A metric tonne is exactly 1,000 kilograms (about 2,204.62 pounds). A US ton — also called a short ton — is 2,000 pounds, or about 907.18 kilograms, so it's noticeably lighter than a tonne. Choosing the right one matters for freight, so both are included as separate units.
Can I convert very large or very small numbers?
Yes. The converter handles everything from a fraction of a milligram to many tonnes. Extremely large or small results are shown in scientific notation so they stay readable and precise, and you can round the displayed answer to whatever precision your task needs.