Convert mass and weight units with precision
| Unit | Symbol | = Kilograms | Common Use |
|---|---|---|---|
| Metric Ton | t | 1,000 | Heavy freight |
| Kilogram | kg | 1 | SI base unit |
| Pound | lb | 0.453592 | US body weight |
| Stone | st | 6.35029 | UK body weight |
| Gram | g | 0.001 | Food, cooking |
| Ounce | oz | 0.0283495 | Food portions |
| Milligram | mg | 0.000001 | Medicine dosage |
| Microgram | mcg | 0.000000001 | Pharmacology |
A weight converter is a tool that transforms a weight or mass value from one unit to another. Weight and mass are related but distinct concepts — weight is the force due to gravity, while mass is the amount of matter. In everyday use, the terms are used interchangeably. Units like kilograms and pounds measure mass, but are commonly called weight units in practical contexts.
From cooking recipes that list ingredients in grams to fitness trackers showing body weight in pounds, weight conversions are needed daily. Our free Weight Converter on Calculator Expert handles all major units in both the metric and imperial systems.
All conversions use kilograms as the base unit:
Example: Convert 150 lbs to kg:
Weight converters are used across many professions and daily activities. Cooks and bakers convert grams to ounces when following foreign recipes. Gym-goers and athletes track body weight in kg or lbs depending on their country. Medical professionals measure drug dosages in milligrams or micrograms. Logistics companies calculate shipping weights in metric tons. Scientists work with microgram-level precision in laboratory experiments.
The metric system uses powers of 10: 1 kg = 1,000 g = 1,000,000 mg. For imperial to metric: 1 lb = 0.4536 kg and 1 oz = 28.35 g. To convert kg to lb: multiply by 2.2046. For stone to kg: multiply by 6.3503. These factors are derived from internationally agreed-upon definitions.
Technically, mass is measured in kilograms (a true scalar quantity), while weight is a force measured in Newtons. However, in common use and everyday calculators, kg and lb are treated as "weight" units. On different planets, your weight changes but your mass does not. This calculator deals with everyday mass/weight conversions as commonly understood.
Enter your weight value, select the unit you are converting from, choose your target unit, and click Convert. The result appears instantly with a full conversion statement. This tool works on all devices — mobile, tablet, and desktop.
This tool supports standard international weight/mass units only. Regional units like tolas, maunds, or carats are not included. For pharmaceutical precision beyond milligrams, consult certified laboratory tools. Gravity effects on weight are not accounted for — this is a mass-to-mass converter.