What this calculator does
Change kilograms to pounds, or pounds to kilograms, in one step. These are the two units most people meet when they weigh themselves, a suitcase or a bag of flour. The kilogram is the basic metric (SI) unit of mass, used almost everywhere outside the United States. The pound is used for body weight in the US, and in the UK alongside the stone. Luggage limits, gym plates, shipping labels and medical forms often switch between the two.
The link between them is fixed by law. Since 1959, one pound has been exactly 0.45359237 kilograms. So pounds to kilograms is one exact multiplication, and kilograms to pounds is one exact division. Enter a weight and choose the direction. You'll see the answer, the number used to convert, and the same weight in pounds and ounces. There's also a chart from 0.5 kg to 200 kg.
Where it's used
Why this math matters outside the classroom:
- Gym plates. A 20 kg barbell plate weighs about 44.1 lb.
- Luggage limits. A 23 kg checked-bag limit is about 50.7 lb.
- Birth weight. A newborn weighing 3.5 kg is about 7 lb 11½ oz.
- Cooking times. A 2 kg roast is about 4.4 lb, which matters for cooking times written per pound.
- Freight. Freight forwarders list a 150 kg crate as about 331 lb for a US carrier.
Grade level and standards: Grades 5–6; Common Core State Standards for Mathematics 6.RP.A.3.d. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Enter the weight. Decimals are fine, so 72.5 kg or 160.4 lb work as typed.
- Choose the direction: kilograms to pounds, or pounds to kilograms.
- Read the converted weight. Going from kg, you also get pounds and ounces, which is handy for baby weights and recipes. Going from lb, you also get grams.
- Open the chart under the result to read off nearby values without retyping.
What the inputs mean
- Value to convert
- A weight in kilograms (for kg → lb) or pounds (for lb → kg). The pound here is the everyday pound of 16 ounces, called the avoirdupois pound.
- Direction
- Which way to convert. The chart under the result switches to match.
Formula and method
lb = kg ÷ 0.45359237 ≈ kg × 2.20462262185 kg = lb × 0.45359237 ounces = (lb − whole pounds) × 16
In the formulas, kg is the weight in kilograms and lb is the weight in pounds. Everything rests on one fact: 1 lb = 0.45359237 kg. The US, the UK and other Commonwealth countries agreed on that exact number in 1959. So going from pounds to kilograms is an exact multiplication.
Going the other way, 1 ÷ 0.45359237 is a decimal that never ends: 2.2046226218… pounds per kilogram. So the calculator divides by the exact number instead, which avoids any rounding. Multiplying by 2.20462262185 gives the same answer, within a billionth of a pound, for everyday weights.
A pound has 16 ounces. So to turn the decimal part of a pound amount into ounces, multiply it by 16. The calculator rounds the ounces to one decimal place. If that reaches a full 16 oz, it adds one to the pounds instead.
Worked example
Convert a body weight of 70 kg to pounds, and to pounds and ounces.
- 1 lb is exactly 0.45359237 kg, so divide: 70 ÷ 0.45359237 = 154.3235835…
- Keep the 154 whole pounds. The leftover 0.3235835 lb × 16 = 5.18 oz, which rounds to 5.2 oz.
Result: 70 kg is about 154.32 lb, or 154 lb 5.2 oz. Checking the other way, 154.32 × 0.45359237 ≈ 70.00 kg.
Understanding the result
Here's a handy trick for kg to lb in your head: double the kilograms, then add 10% of that. For 70 kg, double is 140, and adding 14 gives 154. That's within a third of a pound of the exact 154.32. For lb to kg, halve the pounds and take away 10% of the half. So 160 lb → 80 − 8 = 72, close to the exact 72.57 kg.
A few numbers worth remembering: 1 kg ≈ 2.2 lb and 10 kg ≈ 22 lb. A common checked-bag limit of 23 kg is about 50.7 lb, and 100 kg is about 220.5 lb. A 20 kg weight plate is about 44.1 lb, and a 45 lb plate is about 20.4 kg. That's why gym plates in the two systems are close but never the same.
One thing that trips people up: "lbs" is only the short form for more than one pound, from the Latin word libra. It isn't a different unit. Another is stones: 11 st 4 lb means 11 × 14 + 4 = 158 lb, not 11.4 stone.
Assumptions and limitations
- The pound is the international (avoirdupois) pound, exactly 0.45359237 kg.
- Weights are treated as mass, the way bathroom and kitchen scales show them.
- Troy pounds, used in the past for precious metals, are a different, lighter unit. They aren't covered.
- The result is shown to several decimal places. Round it to match the scale you weighed on.
- Ounces in the pounds-and-ounces line are rounded to 0.1 oz, and the chart shows two decimals. Use the main result when you need more precision.
Frequently asked questions
How many pounds are in one kilogram?
2.20462262185 lb, to 12 digits. It's 1 divided by the exact 0.45359237 kg in a pound, so the decimal never ends.
Is 2.2 accurate enough?
For most things, yes. Using 2.2 instead of 2.20462 gives about 0.2% too few pounds. So 100 kg comes out as 220 lb instead of 220.46 lb. For shipping charges or anything you pay for by weight, use the exact number.
Why does my scale show a slightly different number after switching units?
Scales round each unit on its own, often to 0.1 kg or 0.2 lb. A reading of 70.0 kg can be anything from 69.95 to 70.05 kg. That's 154.2 to 154.4 lb. So the scale's number can differ from the exact conversion by a tenth or two.
How do I convert kilograms to pounds and ounces?
Convert to pounds first. Then multiply the decimal part by 16 to turn it into ounces. A 3.5 kg newborn is 7.716 lb, and 0.716 × 16 = 11.5, so the baby weighs 7 lb 11.5 oz. The calculator shows this line for you when converting from kg.
How many pounds is 100 kg?
100 kg is 220.46 lb, or 220 lb 7.4 oz. Since the conversion is one multiplication, every 10 kg adds 22.05 lb. So 50 kg is 110.23 lb and 200 kg is 440.92 lb.
Are kilograms a weight or a mass?
Strictly speaking, a mass. In physics, weight is a force measured in newtons. But in everyday life, people use both kilograms and pounds for how much they weigh. That everyday meaning is what this converter handles.
How this calculator is checked
Method: International yard and pound agreement (1959): 1 lb = 0.45359237 kg exactly. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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