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Unit converters
Weight and Mass Converter (kg, lb, oz)
Free online weight and mass converter
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About this tool
About this tool
Weight Converter converts mass between milligrams, grams, kilograms, metric tons, ounces, pounds, stones, and US or UK tons using exact international definitions. Type any value, select source and target units, and read the result immediately, with a complete table of all conversions below. Processing is 100 percent client-side.
Switch between metric and imperial weight units for cooking, fitness, shipping, and trade. Enter a value once and see it in every supported unit, from milligrams to long tons, with the main result shown in the unit you choose. All math runs in your browser, so recipes, body weight, and package weights stay private.
Built for daily work
- Convert a recipe ingredient from ounces to grams.
- Check body weight in kilograms against a pounds-based chart.
- Compare parcel weights between pounds and kilograms for couriers.
- Convert cargo weight between metric tons and long tons.
How to use this tool
How to use this tool
Choose source and target
Pick the unit you have on the left and the unit you need on the right, then swap if you change your mind.
Review all units
The table below lists the same mass in every unit so you can compare values at a glance.
Key features
Key features
Metric and imperial in one place
Nine units cover everyday and commercial use, from milligrams for precision to long tons for heavy cargo.
Exact conversion factors
The tool uses the official definitions, including the exact 0.45359237 kilogram pound and the 6.35029318 kilogram stone.
Instant results
Every keystroke updates the main result and the full unit table with no button presses.
Private by default
Weights are processed locally. Nothing is stored or transmitted.
Practical use cases
Practical use cases
- Convert a recipe ingredient from ounces to grams.
- Check body weight in kilograms against a pounds-based chart.
- Compare parcel weights between pounds and kilograms for couriers.
- Convert cargo weight between metric tons and long tons.
- Translate gym plate weights between pounds and kilograms.
Private by default
For local tools, input is processed in your browser and is not sent to application analytics.
Data processing noticeTechnical details
Technical details
ProcessingLocal browser processing
Supported units9 units across metric and imperial systems
InputFree numeric entry
ReferenceInternational exact definitions
Limitations and important notes
Limitations and important notes
- The tool converts mass units, not force; pounds-force and newtons are out of scope.
- Very small masses in tons produce tiny decimals that are shown in scientific notation.
- Rounding for display does not affect internal precision.
Frequently asked questions
Frequently asked questions
A US short ton is 2000 pounds (907.18474 kg). A UK long ton is 2240 pounds (1016.0469088 kg). The metric ton is exactly 1000 kilograms.
Stones are common for body weight in the UK and Ireland, with one stone equal to exactly 14 pounds.
The converter preserves precision and rounds only for display. Small units like milligrams produce long decimals when converted to tons.
Yes. On Earth the practical difference is negligible, and this tool converts mass units as they are used in daily life and trade.
Related guides and solutions
Related guides and solutions
How to convert cooking units: grams, cups, and ounces
A guide to converting cooking measurements: grams, cups, ounces, and milliliters, with the density caveats that matter in recipes.
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