Weight Converter

Convert one weight or mass unit to another

Enter a number, choose its current unit, and select the unit you need. The converter shows a readable result plus the factor used for that direction.

Weight and mass in everyday use

People often say “weight” when labels and measurements technically describe mass. Kilograms, grams, pounds, ounces, stone, and tonnes are treated here as mass units. True weight is a force that changes with gravity; that distinction matters in physics and engineering but rarely changes a recipe, parcel label, or personal measurement.

Conversion method

Every input is first converted to kilograms using a fixed factor, then converted from kilograms to the destination unit. One international avoirdupois pound is exactly 0.45359237 kilograms, and one pound contains exactly 16 avoirdupois ounces. One stone is 14 pounds. A metric tonne is 1,000 kilograms, while a US short ton is 2,000 pounds.

Worked example

Convert 10 kilograms to pounds. Divide 10 by 0.45359237 to get approximately 22.046226 pounds. Rounded to a practical two decimals, that is 22.05 lb. Reversing the conversion—22.046226 pounds multiplied by 0.45359237—returns very close to 10 kilograms, with tiny display differences possible from rounding.

Ounces can mean different things

This page uses the avoirdupois ounce for mass, the ordinary ounce used for most packaged goods in the United States. A fluid ounce measures volume and cannot be converted to grams without knowing the substance's density. Troy ounces, used for precious metals, are also different and are not included.

Choosing sensible precision

The result may display more decimals than your measurement deserves. A bathroom scale reading to the nearest pound does not become laboratory-accurate after conversion. Round based on the source measurement and the job: recipes may need grams, shipping may follow carrier increments, and structural work may require specified tolerances.

Accuracy and limitations

Factors are fixed and calculations run locally in your browser. The converter does not account for scale calibration, buoyancy, local gravity, packaging tare, or legal metrology rules. It accepts negative numbers mathematically, though negative mass is not meaningful for ordinary objects. Confirm unit definitions when working with historical units, trade-specific tons, or regulated labels.