Weight Converter

How to use the Weight Converter

Convert common mass and weight units with standard conversion factors between metric and imperial measurements.

Convert mass values among milligrams, grams, kilograms, ounces, pounds, stones, and metric tons. Everyday language often says weight, while the mathematical conversion relates unit quantities of mass.

The conversion runs locally using the stated factors or formulas. Keep enough precision for the task and verify regulated or engineering work against its controlling standard.

1. Enter a numeric value.
2. Choose the starting unit and target unit.
3. Fieldlet converts the source amount through kilograms and displays the equivalent.

Last reviewed for accuracy: 2026-08-31

Worked examples

How the result is produced

The converter uses kilograms as a base and applies defined unit factors. Avoirdupois ounces and pounds are used, not troy units used for some precious metals.

• 1 avoirdupois pound = exactly 0.45359237 kilograms
• 16 avoirdupois ounces = 1 pound
• Mass conversion does not account for a scale's calibration or local gravity

Mass units belong to different families

The converter uses avoirdupois ounces and pounds for ordinary mass measurements. Troy ounces, fluid ounces, and force measurements use different definitions, so a shared unit name is not enough to choose the correct conversion.

• 1 stone = exactly 14 avoirdupois pounds.
• 1 metric ton = exactly 1,000 kilograms.
• Round the converted value to match the source measurement's precision.

References

These primary references document standards or definitions used in the explanation above.

• NIST SI unit information

Limitations and common mistakes

• Troy ounces and fluid ounces are different units and are not interchangeable with avoirdupois ounces.
• Shipping and medical decisions may require certified equipment and prescribed rounding.

Common questions