Weight and Mass Converter – kg, lb, oz and stone

Convert mass between kg, grams, pounds, ounces and stone

Metric units are standard in most countries, but pounds, ounces, and stone remain common in recipes, gym equipment, shipping, and body-weight records. Converting from one shared base avoids inconsistent rounding.

Metric mass

One gram is 1,000 milligrams, one kilogram is 1,000 grams, and one metric tonne is 1,000 kilograms. A hectogram is 100 grams; it is still familiar in parts of Europe even if English speakers rarely use it day to day.

Pounds and ounces

The international avoirdupois pound is exactly 0.45359237 kg and contains exactly 16 ounces. One kilogram is therefore approximately 2.20462 lb.

Imported gym plates are often marked 45 lb, about 20.4 kg. Include the bar itself when comparing the total load of a lift.

Stone and body weight

Stone is still used mainly in the UK and Ireland. One stone is exactly 14 pounds, approximately 6.35029 kg. A mixed value such as 11 st 4 lb must combine both parts before conversion.

Mass is not volume

Grams measure mass; cups and tablespoons measure volume. There is no universal conversion between them. A cup of water, flour, sugar, and oil each has a different mass because their densities and packing differ.

Use an ingredient-specific reference for recipe volume. This calculator converts mass units only and does not assume a density.

Shipping and baggage

Postal tiers and baggage allowances can have strict limits. Weigh packaging as well as contents and avoid rounding down near a boundary. Always check the carrier’s current rules; converting the unit does not change the allowance.

Check the scale

An apple weighs a few hundred grams, an adult tens of kilograms, and a car more than a metric tonne. A result many orders of magnitude away usually means grams and kilograms were confused or a decimal was misplaced.