Weight Converter: Pounds, Kilograms, Ounces, Grams
Convert weight between pounds, kilograms, ounces, and grams. Enter a value in one unit to see the exact equivalent in the other three units at once, instantly.
Weight Converter
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Weight Converter
A weight converter changes a weight value from one unit into another, such as pounds into kilograms or grams into ounces. This tool converts between pounds (lb), kilograms (kg), ounces (oz), and grams (g). Enter a value and pick its starting unit, and the tool shows the same weight in the other three units at once.
How to convert weight units
Enter a weight value in the input box. Choose the unit that value is measured in from the dropdown menu: pounds, kilograms, ounces, or grams. The tool then shows the equivalent weight in the other three units. Changing the number or the unit updates the results right away.
The tool accepts zero and positive numbers only, since a negative weight has no real-world meaning. It shows results to four decimal places.
Weight conversion formula
Every conversion in this tool works the same way. First, the entered value is converted to grams, since grams serve as the common base unit. Then grams are converted to whichever unit is needed:
target value = (source value × grams per source unit) ÷ grams per target unit
The grams-per-unit figures are fixed by international definition:
| Unit | Grams per unit |
|---|---|
| Pound (lb) | 453.59237 |
| Kilogram (kg) | 1,000 |
| Ounce (oz) | 28.349523125 |
| Gram (g) | 1 |
These come from the international avoirdupois pound, defined in 1959 as exactly 0.45359237 kilograms. An ounce is one-sixteenth of a pound, which gives 28.349523125 grams exactly. Because the pound and the kilogram are linked by an exact figure, every conversion between pounds, ounces, kilograms, and grams is also exact — there is no rounding built into the definitions themselves, only in how many decimal places a result is displayed with.
From these base figures, the everyday conversion factors are:
- 1 kilogram = 2.20462262 pounds
- 1 pound = 0.45359237 kilograms
- 1 pound = 16 ounces
- 1 ounce = 0.0625 pounds
- 1 ounce = 28.349523125 grams
- 1 gram = 0.035273962 ounces
Example weight conversions
Pounds to kilograms. Multiply pounds by 0.45359237. 10 lb × 0.45359237 = 4.5359237 kg
Kilograms to pounds. Multiply kilograms by 2.20462262. 5 kg × 2.20462262 = 11.0231131 lb
Ounces to grams. Multiply ounces by 28.349523125. 4 oz × 28.349523125 = 113.398093 g
Grams to ounces. Divide grams by 28.349523125. 250 g ÷ 28.349523125 = 8.8185 oz
Pounds to ounces. Multiply pounds by 16. 2.5 lb × 16 = 40 oz
Common weight conversions
The table below lists frequently searched conversions.
| From | To | Result |
|---|---|---|
| 1 lb | kg | 0.4536 kg |
| 1 kg | lb | 2.2046 lb |
| 150 lb | kg | 68.0389 kg |
| 1 oz | g | 28.3495 g |
| 100 g | oz | 3.5274 oz |
| 8 oz | g | 226.7962 g |
Why two systems are still in use
Most countries use the metric system, built around grams and kilograms, for everyday weighing. The United States still uses pounds and ounces for most daily purposes, alongside the metric system in science, medicine, and much of manufacturing. A weight converter bridges the two, which is useful for cooking from a foreign recipe, reading a shipping label in another country's units, or comparing a bathroom scale reading to a doctor's chart.
Frequently asked questions
How accurate are these conversions? The factor between pounds and kilograms is exact by international agreement, so a conversion carries no built-in error. Any imprecision comes only from how a result is rounded for display, not from the conversion itself.
Is weight the same as mass? Not exactly. Mass measures the amount of matter in an object and stays the same everywhere. Weight measures the pull of gravity on that mass and changes slightly with location, such as on the Moon. A kitchen or bathroom scale actually reads mass, and this converter follows that everyday usage.
Does 1 kilogram really equal 2.2 pounds? Close enough for most purposes. The exact figure is 2.20462262 pounds. Rounding to 2.2 is fine for quick estimates but not for precise work like a lab measurement or a medication dose.
Are ounces for gold the same as ounces for food? No. This converter uses the standard avoirdupois ounce (28.349523125 g), used for food, mail, and most everyday items. Precious metals such as gold and silver are weighed in troy ounces, which equal about 31.1035 grams — roughly 10% heavier than a standard ounce.
What precision should I use for shipping? Most carriers round to the nearest 0.1 lb or 0.1 kg. Rounding a package's weight up slightly, rather than down, avoids disputes over declared weight.
Can I convert medication doses with this tool? Use it only to check a figure, not to decide a dose. Follow a prescriber's instructions in the units given, since a dosing error carries real risk.