Weight Converter
This weight converter switches between pounds, ounces, kilograms and grams, with stones, milligrams and metric tonnes included. Enter one weight and every unit updates live as you type, so pounds to kg for a doctor's form and ounces to grams for a recipe are answered together on one screen.
Weight Converter tool
Converted to every unit
| Unit | Value |
|---|---|
| Pounds (lb) | – |
| Ounces (oz) | – |
| Stones (st) | – |
| Grams (g) | – |
| Kilograms (kg) | – |
| Milligrams (mg) | – |
| Metric tonnes (t) | – |
Tap a row value to copy it.
How to use it
- Type the value you want to convert.
- Pick the unit you are converting from.
- Read every other unit at once, and tap a value to copy it.
What is weight conversion?
Weight conversion, or mass conversion, restates the same heaviness in another unit. Since 1959 the pound has been defined as exactly 0.45359237 kilograms, so every conversion here is exact:
kilograms = pounds × 0.45359237To go from pounds to kilograms, multiply by 0.4536; to go back, multiply kilograms by 2.2046. A 150 lb person weighs 68.04 kg, and a 70 kg person weighs 154.3 lb. Ounces divide the pound by 16, so one ounce is 28.35 grams, and the stone used for body weight in the UK is 14 pounds. All seven units on this page convert through the kilogram.
Worked example
Common weights in pounds and kilograms
| Pounds | Kilograms | Handy reference |
|---|---|---|
| 50 lb | 22.7 kg | Common US checked-bag limit |
| 100 lb | 45.4 kg | |
| 125 lb | 56.7 kg | |
| 150 lb | 68.0 kg | |
| 175 lb | 79.4 kg | |
| 200 lb | 90.7 kg | |
| 250 lb | 113.4 kg |
Pounds, ounces and kilograms
A pound is defined as exactly 0.45359237 kilograms, and there are 16 ounces in a pound, so an ounce is 28.3495 grams. Those fixed definitions, agreed in 1959, mean the conversions here are exact, which matters for shipping weights, recipes and lab work where small errors add up. In the other direction, a kilogram is 2.20462 pounds, or 2 lb 3.27 oz, and 100 grams is 3.527 ounces.
Body weight is the usual reason to convert. A person at 150 lb weighs 68.04 kg; someone at 70 kg weighs 154.3 lb. The stone, still used for body weight in the UK and Ireland, is 14 pounds or 6.35 kg, so 11 st 4 lb is 158 lb or 71.7 kg. Airline baggage limits are often 50 lb, which is 22.68 kg, or 23 kg, which is 50.7 lb. Being a pound over can cost a fee, so check the exact figure rather than rounding.
Units that look alike but are not
Fluid ounces measure volume and weight ounces measure mass. A cup of water is 8 fluid ounces and happens to weigh about 8.3 ounces, but a cup of flour weighs closer to 4.4 ounces. Precious metals use the troy ounce, 31.1035 grams, about 10% heavier than the 28.35 gram avoirdupois ounce in this tool. Tons split three ways: the metric tonne here is 1,000 kg (2,204.6 lb), the US short ton is 2,000 lb (907.2 kg), and the British long ton is 2,240 lb (1,016 kg).
Strictly speaking, pounds and kilograms both measure mass, and what a scale reads is the pull of gravity on that mass. On Earth the distinction rarely matters, and every everyday use, from body weight to postage, treats the two as interchangeable. Because all seven units convert through the kilogram, you can enter a value in any of them and read a package weight in both pounds and kilograms for a customs form, or a recipe amount in grams for a kitchen scale, in a single glance.
Common uses
- Converting body weight between pounds and kilograms
- Reading shipping weights for customs
- Switching recipes between ounces and grams
- Weighing luggage against airline limits
- Reading UK weights given in stones
- Comparing product weights on labels from different countries
When to use it
- You need to convert 150 pounds to kg for a medical or visa form.
- Your suitcase reads 23 kg on a hotel scale and the airline limit is 50 lb.
- A European recipe lists 250 grams of butter and your kitchen scale shows ounces.
- You follow UK sports and want to know what 12 stone is in pounds (it is 168 lb).
- A shipping form wants the package weight in kilograms and your bathroom scale reads pounds.
Related tools
The Length Converter handles the height half of any form that asks for both.
The Volume Converter covers cups and milliliters when a recipe measures liquids instead of weighing them.
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