Weight Converter
Turn any weight into a different unit — metric or imperial — using exact international conversion factors.
Exact factors
Every conversion uses the official 1959 international definitions, so a pound is exactly 453.59237 g — never a rounded approximation.
Display rounding
Results are shown to six decimal places, so very small or very large conversions may round the last digit.
What is a weight converter?
One value, any unit
A weight converter changes a measurement from one unit into another — kilograms to pounds, grams to ounces, tonnes to stone, and back. Strictly speaking it converts mass, but on Earth's surface weight and mass map one-to-one for everyday use, so "weight" and "mass" are interchangeable here. It works by translating every unit through a single shared base, the gram, so any pair of units can be converted with one consistent rule. This tool covers seven common units across the metric and imperial systems, making it useful for cooking, shipping, fitness, travel, and anywhere measurements in different systems need to meet.
Each unit has an exact size in grams. To convert, the value is first turned into grams, then into the target unit.
Result = value × (grams per from-unit) ÷ (grams per to-unit)Because the conversion factors are exact international definitions — ounce = 28.349523125 g, pound = 453.59237 g, stone = 6350.29318 g (14 pounds), and tonne = 1,000,000 g — the result is mathematically exact, limited only by how many decimal places are displayed. The same single rule handles every direction, so converting pounds back to kilograms just swaps which factor divides.
Suppose you want to convert 1 kilogram into pounds.
Find the base size
One kilogram is, by definition, 1000 grams.Divide by the target factor
A pound is 453.59237 grams, so 1000 ÷ 453.59237 = 2.204623.Read the result
1 kilogram converts to about 2.204623 pounds.
The converted figure is exact to the precision shown. Metric units (mg, g, kg, t) scale in powers of ten, so moving the decimal point is often enough between them, while imperial conversions rely on the fixed factors above. For everyday tasks like weighing ingredients or parcels, round the result to a sensible number of decimals; for scientific or trade work, keep the full precision. Stone is mainly a British unit for body weight — one stone is 14 pounds, so a figure that looks small in stone is heavier than it first appears.
The arithmetic is exact; the only limit is display precision.
Mass, not force
This tool converts mass — the amount of matter — not gravitational weight as a force in newtons, which changes with location. The two coincide for everyday use on Earth, so a kitchen scale reading in kilograms converts cleanly to pounds here. Results are rounded to six decimal places, so converting between units that differ enormously in size — milligrams to tonnes, for example — can lose the last digits. Stone is a UK-specific usage; for legal, trade, or precision-manufacturing work, always confirm against the governing standard for your field.