Quick answer: Weight conversion uses exact definitions: one pound is 0.45359237 kilograms, one ounce is 28.3495 grams, and one stone is 6.35029 kilograms. Metric units scale by powers of ten, so a tonne is 1000 kilograms. In science, mass in kilograms stays constant while weight as a force changes with gravity.
Last reviewed: September 2026
Key facts
- 1 kg = 2.20462 lb — the conversion travellers and shoppers need most.
- 1 lb = 0.45359237 kg exactly; 1 oz = 28.3495 g; 1 stone = 14 lb.
- Most of the world uses kilograms; the US, Liberia and Myanmar mainly use pounds.
- Shows a full table of every unit, so one conversion answers every follow-up question.
Recipes, luggage limits, gym plates — weight units change with every border. This free weight converter switches between milligrams, grams, kilograms, tonnes, ounces, pounds and stones instantly, with a complete conversion table for every unit.
Enter a value, pick the from and to units, and read the answer plus every equivalent below. Definitions are exact (1 lb = 0.45359237 kg), so results are precise to the displayed digits.
How to use
- Enter a value.
- Pick the from and to units (swap them in one tap).
- Read the answer and the full table of equivalents below.
How weight conversion works
| Term | Meaning |
|---|---|
| from-unit in kg | Each unit’s exact definition in kilograms. |
| to-unit in kg | The target unit’s definition in kilograms. |
Because every unit is defined against the kilogram, converting is one multiplication — exact, with no chained rounding.
Worked examples
Body weight
70 kg → lb: 70 × 2.20462 = 154.32 lb.
150 lb → kg: 150 × 0.45359237 = 68.04 kg.
Cooking and stones
8 oz → g: 8 × 28.3495 = 226.80 g — a US recipe’s “half pound” in metric.
11 stone → kg: 11 × 14 × 0.45359237 = 69.85 kg.
Weight units in kilograms
| Unit | Equals (kg) | Used for |
|---|---|---|
| Milligram (mg) | 0.000001 | Medicine, supplements |
| Gram (g) | 0.001 | Cooking, food labels |
| Kilogram (kg) | 1 | Body weight, most of the world |
| Tonne (t) | 1,000 | Vehicles, freight, industry |
| Ounce (oz) | 0.0283495 | US cooking, mail |
| Pound (lb) | 0.45359237 | US body weight, groceries |
| Stone (st) | 6.35029 | UK & Ireland body weight |
Tonnes here are metric tonnes (1,000 kg). A US (short) ton is 907.185 kg and a UK (long) ton is 1,016.05 kg.
Frequently asked questions
How many pounds are in a kilogram?
2.20462 lb per kg. Divide pounds by 2.20462 to go the other way.
What is a stone in weight?
A British unit: 1 stone = 14 pounds = 6.35029 kg, still used for body weight in the UK and Ireland.
Kilogram vs pound — which countries use which?
Most of the world uses kilograms; the US, Liberia and Myanmar mainly use pounds. The UK mixes both.
What is the difference between a tonne, a ton and a long ton?
A metric tonne is 1,000 kg. A US short ton is 907.185 kg; a UK long ton is 1,016.05 kg. In international trade, “tonne” almost always means metric.
How many grams in an ounce?
28.3495 g per avoirdupois ounce — the ounce used for food and postage. (Troy ounces for precious metals differ: 31.1035 g.)
Sources
Key takeaways
- 1 kg = 2.20462 lb; 1 lb = 0.45359237 kg exactly; 1 stone = 14 lb.
- Every unit is defined against the kilogram, so conversions are exact.
- Watch out for tonnes vs US/UK tons — three different units share the name.
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