Kilograms to Pounds Converter

Since 1959 the international avoirdupois pound has been defined as exactly 0.45359237 kilograms. That definition is not an approximation or a measurement — it is a legal definition agreed by the United States, the United Kingdom, Canada, Australia, New Zealand, and South Africa in the International Yard and Pound Agreement. Every pound-to-kilogram figure you will ever see derives from that single number.

Inverting it gives 1 kilogram = 1 ÷ 0.45359237 = 2.20462262185 pounds. To go from kilograms to pounds, multiply by 2.2046. To go from pounds to kilograms, divide by 2.2046 or multiply by 0.45359. Both directions are exact within the precision you carry; nothing about the conversion is regional or approximate.

The kilogram itself was redefined in 2019. It used to be the mass of a platinum-iridium cylinder kept outside Paris; it is now defined by fixing the numerical value of the Planck constant. In practice nothing changed for everyday users — the new kilogram was matched to the old one to within a few parts per billion — but the definition no longer depends on a physical object that could be scratched, contaminated, or lost.

For mental arithmetic, doubling and adding 10% gets you very close: 70 kg × 2 = 140, plus 10% = 154 lb, against a true 154.32 lb. Going the other way, halve and subtract 10%: 180 lb ÷ 2 = 90, minus 10% = 81 kg, against a true 81.65 kg. The shortcut runs about 0.2% low, which is fine for conversation and wrong for anything billed by weight.

Strictly, the kilogram measures mass — the amount of matter in an object — while the pound is used in everyday speech as a unit of force, or weight. On Earth's surface the distinction never bites, because a kilogram of mass always registers as about 2.2 pounds on a scale. On the Moon, the same kilogram would weigh a sixth as much while its mass stayed identical.

Engineers keep the two separate with explicit units: pound-mass (lbm) and pound-force (lbf). One pound-force is the weight of one pound-mass in standard Earth gravity of 9.80665 m/s². If you are reading a specification sheet that uses lbf, you are looking at a force, not a quantity of material, and the conversion to newtons rather than kilograms is what you want: 1 lbf = 4.44822 N.

There is also the metric ton and the two imperial tons to keep straight. A metric ton (tonne) is exactly 1,000 kg = 2,204.62 lb. A US short ton is 2,000 lb = 907.18 kg. A UK long ton is 2,240 lb = 1,016.05 kg. Shipping and construction documents frequently mix them, so always check which ton is meant before scaling a quote.

For everyday conversion — body weight, food, luggage, freight under a ton — none of this changes the arithmetic. Multiply or divide by 2.20462 and move on.

The UK and Ireland still quote body weight in stones and pounds. One stone is exactly 14 pounds, so 80 kg is 176.4 lb, which is 12 stone 8.4 lb, usually written 12st 8lb. The stone is essentially unused in the United States, where the same weight would simply be '176 pounds', and unused in metric countries, where it would be '80 kilos'.

Ounces matter below the pound. There are 16 ounces in an avoirdupois pound, so 0.4 lb is 6.4 oz. Infant weights, postal rates, and most American recipes use pounds-and-ounces rather than decimal pounds. Note that the fluid ounce is a volume, not a weight, and the two are only interchangeable for water at room temperature — a mistake that ruins baking conversions constantly.

Precious metals use a different pound entirely. The troy ounce is 31.1035 grams versus the avoirdupois ounce at 28.3495 grams, and a troy pound contains only 12 troy ounces, making it 373.24 grams rather than 453.59. If you are converting gold, silver, or platinum weights, the ordinary conversion on this page is the wrong one.

Grams are the right unit below about half a kilogram. Nutrition labels, coffee doses, medication, and postal items are almost always specified in grams internationally and in ounces in the United States. One ounce is 28.35 g, and 100 g is 3.53 oz — worth memorising if you read recipes from both traditions.

A traveller flying from Frankfurt to Chicago has a checked-bag allowance of 23 kg with the European carrier and 50 lb on the connecting US carrier. Converting: 23 kg × 2.20462 = 50.71 lb, and 50 lb ÷ 2.20462 = 22.68 kg. The allowances look identical in marketing copy but the US limit is about 320 g tighter.

The bag on the home scale reads 22.9 kg. Against the European limit there is 100 g of headroom; against the US limit of 22.68 kg the bag is 220 g overweight, which on many carriers triggers a flat overweight fee rather than a proportional one. Removing a paperback solves a problem that the marketing numbers hid.

Carry-on allowances make the gap wider because the numbers are smaller. A 7 kg cabin limit is 15.43 lb; carriers that advertise '15 lb' are actually 200 g stricter than the metric figure suggests. When two limits are quoted for the same journey, convert both and plan against the tighter one.

The general rule for anything with a hard threshold — baggage, freight class breaks, shipping bands, weight-based tolls — is to convert first, then compare, and never to assume that a rounded metric limit and a rounded imperial limit describe the same weight.

Kilograms to pounds — 1 kg = 2.20 lb · 5 kg = 11.02 lb · 10 kg = 22.05 lb · 20 kg = 44.09 lb · 45 kg = 99.21 lb · 50 kg = 110.23 lb · 60 kg = 132.28 lb · 70 kg = 154.32 lb · 80 kg = 176.37 lb · 90 kg = 198.42 lb · 100 kg = 220.46 lb.

Pounds to kilograms — 10 lb = 4.54 kg · 25 lb = 11.34 kg · 50 lb = 22.68 kg · 100 lb = 45.36 kg · 120 lb = 54.43 kg · 150 lb = 68.04 kg · 180 lb = 81.65 kg · 200 lb = 90.72 kg · 250 lb = 113.40 kg · 300 lb = 136.08 kg.

Common body weights in stones — 60 kg = 9st 6lb · 70 kg = 11st 0lb · 75 kg = 11st 11lb · 80 kg = 12st 8lb · 90 kg = 14st 2lb · 100 kg = 15st 10lb.

Small weights — 100 g = 3.53 oz · 250 g = 8.82 oz · 500 g = 1.10 lb · 1 oz = 28.35 g · 8 oz = 226.8 g · 1 lb = 453.6 g.

Medication dosing is the highest-stakes case. Paediatric and oncology doses are prescribed per kilogram of body weight, but American patients report their weight in pounds. A chart weight entered in pounds and treated as kilograms produces a dose 2.2 times too high. Every clinical system should force the unit, and every practitioner should sanity-check that an adult weight in kilograms is a number between roughly 40 and 200.

Freight and logistics is the most expensive case. Air freight is billed on chargeable weight, the greater of actual and volumetric weight, and carriers quote in kilograms internationally and pounds domestically. Mixing them inside a rate comparison makes a cheap carrier look expensive by a factor of two.

Strength training is the most common case. Olympic bars and plates are manufactured in kilograms internationally and in pounds in most American gyms. A 20 kg bar is 44 lb, not 45 lb, and a 'plate' means 20 kg to one lifter and 45 lb to another. Loading a percentage-based program without checking which bar you are on introduces a 2% error in every set.

Cooking is the most forgiving. Recipes tolerate a few percent on most ingredients, but baking by weight — the entire reason to weigh flour rather than scoop it — does not. Convert to grams for baking and skip pounds and ounces entirely; every serious baking recipe published in the last decade uses grams for exactly that reason.