Free online tool
Weight Converter
Convert weights across metric and imperial units in one place.
Metric and imperial weights
Most of the world weighs in grams and kilograms, while the US uses ounces and pounds and the UK still measures body weight in stones. A stone is exactly 14 pounds, or about 6.35 kilograms. When you're reading a recipe, filling in a shipping form, or checking a fitness result written in unfamiliar units, a converter saves a lot of second-guessing.
Precision matters
For everyday use, two decimal places is enough. For shipping, medical, or scientific work, use the full precision this tool offers — 1 pound is exactly 453.59237 grams, and rounding early can add up over many items.
+Is a US ton the same as a metric tonne?
No. A US short ton is 2,000 lb (about 907 kg); a metric tonne is exactly 1,000 kg.
+Are troy ounces supported?
Not in this tool. Troy ounces are used only for precious metals and differ from standard (avoirdupois) ounces.
Mass and weight conversions, kitchen scale to shipping label
Weight conversion factors are defined precisely by international standards bodies, not rounded for convenience, which matters if you're working with cooking recipes at one extreme or freight manifests at the other.
It also helps to know which units are used where, since a pound in a US recipe and a stone on a UK bathroom scale aren't interchangeable without doing the arithmetic first.
The defining factor
One international avoirdupois pound equals exactly 0.45359237 kilograms — that's the legal definition, not an approximation, agreed by the US, UK and Commonwealth countries in 1959. From that single number everything else follows: one ounce is 1/16 of a pound, or roughly 28.3495 grams, and one stone (used mainly in the UK and Ireland) is 14 pounds, about 6.35 kg.
Metric ton versus imperial ton
A metric tonne is 1,000 kg. A US short ton is 2,000 lb (about 907.18 kg), and a UK long ton is 2,240 lb (about 1,016.05 kg) — three different 'tons' that differ by several percent, which matters a lot in shipping contracts and matters even more if the wrong one ends up on an invoice.
Worked example
A recipe calling for 2.2 lb of flour converts to almost exactly 1 kg (2.2 x 0.45359237 = 0.998 kg), which is why '2.2 pounds per kilogram' became the everyday rule of thumb even though the true factor carries more decimal places.
Kitchen-scale precision versus shipping precision
Baking is forgiving of small rounding — a gram or two of flour won't ruin a loaf — so converting 8 oz of butter to 227 g (rather than the exact 226.796 g) is perfectly fine. Freight and customs declarations are the opposite: a shipment declared at 907 kg versus a true 907.18 kg can trip a rounding rule in a tariff calculation, so professional logistics software generally carries the full decimal factor rather than a rounded one.
Body weight and the stone
The stone remains in everyday use in the UK and Ireland for body weight specifically, even though most other measurements there have gone fully metric. A person weighing 11 stone 6 lb is (11 x 14) + 6 = 160 lb, or about 72.6 kg — a two-step conversion that trips up anyone unfamiliar with reading stone-and-pounds notation.
Why avoirdupois isn't the only pound
The avoirdupois pound used for everyday weight is not the same as the troy pound used historically for precious metals — a troy pound is about 373.24 grams and contains 12 troy ounces rather than 16, and a troy ounce is actually heavier than an avoirdupois ounce despite the troy pound being lighter overall. Gold and silver prices quoted 'per ounce' almost always mean troy ounces, a distinction that matters if you're ever comparing precious metal prices against a kitchen scale reading.
People also search for
- kg to lbs converter
- pounds to kilograms calculator
- stone to kg conversion
- grams to ounces converter
- weight unit converter online
- convert lbs to stone
- metric ton vs short ton