Weight Converter
Convert kilograms, pounds, ounces, grams and stones (as you type).
1 kg = 2.204623 lb
Quick conversions
This converts between kilograms, grams, pounds, ounces and stones.
The pound is defined exactly in metric terms, so these conversions are precise rather than approximate.
How weight units relate
Weight conversion is one multiplication, and the anchor is that one pound is defined as exactly 0.45359237 kilograms. That is a definition set by international agreement in 1959, not a measured approximation.
So 1 kg is 2.204623 lb. A 70 kg person is 154.3 lb, and 180 lb is 81.6 kg.
The unit that catches people out is the stone, used for body weight in the UK and Ireland: 1 stone = 14 pounds. A UK weight of "11 stone" is 154 lb, and the mixed form "11 stone 4" means 11 × 14 + 4 = 158 lb.
A stone is 14 pounds, which is why UK body weights need two numbers and are not directly comparable to a single US figure.
What to enter
- Value and unit
- The weight to convert. Stones and pounds can be entered as a combined value.
- Target unit
- Kilograms, grams, pounds, ounces or stones.
Conversion factors
- 1 pound
- 0.45359237 kg exactly. 16 ounces.
- 1 kilogram
- 2.204623 lb, or about 2.2 for mental arithmetic.
- 1 ounce
- 28.3495 g. Sixteen to a pound.
- 1 stone
- 14 lb, or 6.35 kg. Used for body weight in the UK and Ireland.
- 1 metric tonne
- 1,000 kg, or 2,204.6 lb. Distinct from a US short ton at 2,000 lb.
What this assumes
These are avoirdupois units, the everyday system. Troy ounces, used for precious metals, are heavier at about 31.1 g.
Strictly these convert mass, not weight. In everyday use the distinction does not matter, since we all weigh things on the same planet.
How to calculate weight conversion
Multiply by the factor, or divide to reverse it.
- 0.45359237
- Exact by definition since 1959
- stone
- 14 lb, so 11 st 4 lb is 158 lb
Flatten compound units first. 11 stone 4 pounds becomes (11 × 14) + 4 = 158 lb before converting anything.
Multiply by the factor. 158 × 0.45359237 = 71.7 kg.
Divide to reverse. 70 kg ÷ 0.45359237 = 154.3 lb, or equivalently 70 × 2.204623.
Use 2.2 for mental estimates. 70 kg × 2.2 = 154, which is within half a pound of the exact answer.
See a worked example: converting a body weight three ways
- Weight
- 70 kg
To pounds: 70 × 2.204623 = 154.3 lb.
To stones: 154.3 ÷ 14 = 11.02, so about 11 stone.
Back the other way: 180 lb × 0.45359237 = 81.6 kg.
The mental shortcut of × 2.2 gives 154 for 70 kg, close enough for anything but a prescription.
154.3 lb, or about 11 stone
Frequently asked questions
2.204623 lb. For mental arithmetic, 2.2 is close enough: 70 kg × 2.2 gives 154, against an exact 154.3.
The relationship is exact by definition, since a pound is defined as 0.45359237 kg.
14 pounds, or about 6.35 kg. It is used for body weight in the UK and Ireland and almost nowhere else.
UK weights are usually given as stones and pounds: "11 stone 4" means 11 × 14 + 4 = 158 lb, which is 71.7 kg.
Double it and add 10%. 70 kg doubled is 140, plus 14 is 154. The exact answer is 154.3.
Going the other way, halve and subtract 10%: 154 halved is 77, less 7.7 is 69.3, against an exact 69.9. Slightly less accurate but usable.
A metric tonne is 1,000 kg, which is 2,204.6 lb. A US short ton is 2,000 lb, which is 907.2 kg. A UK long ton is 2,240 lb.
They are close enough to be confused and far enough apart to matter. Shipping and freight quotes should always specify which.
No. A troy ounce is about 31.1 g, against 28.35 g for the everyday avoirdupois ounce, so it is roughly 10% heavier.
Troy is used for gold, silver and other precious metals. A troy pound is also only 12 troy ounces, not 16, which compounds the confusion.
Strictly no. Mass is how much matter something contains; weight is the force gravity exerts on it. Kilograms measure mass, and newtons measure force.
In everyday use the distinction does not matter, because gravity is effectively constant everywhere we weigh things. It only matters in physics and off the planet.
Problems people actually run into
Reading a UK weight as a single number
"11 stone 4" is not 11.4 stone. It is 11 stone plus 4 pounds, which is 158 lb.
Convert stones to pounds and add the remainder before doing anything else. Treating the second number as a decimal produces an answer several pounds out.
Using 2 instead of 2.2
Doubling kilograms to get pounds is quick and 10% low. 70 kg becomes 140 rather than 154.
Double and add 10%. It takes one extra step and lands within half a pound.
Results are estimates for general information only and are not professional financial, medical, or legal advice. Read our full disclaimer.
Last updated: September 4, 2026