Weight Converter

How weight conversion works

All weights are converted through kilograms using exact definitions — the international pound has been fixed at 0.45359237 kg since 1959, and every other unit derives from it. The only rounding is the precision you pick.

result = value × kilograms(from) ÷ kilograms(to)

Exact factors

Worked examples

• 10 kg to pounds — 10 ÷ 0.45359237 = 22.05 lb.
• 165 lb to kilograms — 165 × 0.45359237 = 74.84 kg.
• 12 stone to kilograms — 12 × 6.35 = 76.20 kg.

Mass vs. weight

Strictly speaking, kilograms and pounds measure mass — how much matter an object contains — while weight is the force gravity exerts on that mass. In everyday use the two words are interchangeable because gravity is effectively constant across the Earth's surface, so a converter that maps units through kilograms gives the answer people expect on a bathroom scale or a shipping label.

Quick reference

For fast estimates: 1 kg ≈ 2.2 lb, 1 lb ≈ 454 g, 1 oz ≈ 28 g, and 1 stone = 14 lb ≈ 6.35 kg. So 70 kg is roughly 154 lb or 11 stone. The calculator uses the exact 0.45359237 kg pound definition for precise results, which matters most for recipes, medication, and freight.

kg to stone and pounds for body weight

In the UK and Ireland body weight is given in stones and pounds — 11 st 4 lb rather than 158 lb — so converting from kilograms takes two steps: kilograms to pounds, then whole stones and the pounds left over.

pounds = kg ÷ 0.45359237  ·  stones = ⌊pounds ÷ 14⌋  ·  leftover = pounds − stones × 14

For a figure between rows, such as 71.7 kg: 71.7 ÷ 0.45359237 = 158.1 lb, and 158 lb is 11 stone (154 lb) with 4 lb over — 11 st 4 lb, or 11.29 stone as a decimal. Going the other way, multiply stones by 14, add the loose pounds, and multiply by 0.45359237.

Metric prefixes: hectogram, dekagram, decigram

Every metric prefix is a plain power of ten away from the gram, so these need no lookup table — shift the decimal point. A kilogram is 1,000 g, which makes it 10 hectograms (hg), 100 dekagrams (dag, also written dkg), and 10,000 decigrams (dg).

Kilograms and force: kgf, newtons, and ft·lb

A kilogram is mass, but a mass sitting in Earth's gravity produces a force. One kilogram-force (kgf) is defined as the pull on 1 kg at standard gravity, so 1 kgf = 9.80665 newtons, and 1 kg therefore corresponds to about 0.00981 kilonewtons (kN). This is a definition, not a measurement — it only holds at standard gravity, which is why engineers prefer newtons outright.

force in N = mass in kg × 9.80665

Foot-pounds are a different quantity again. A ft·lb measures torque or energy, not mass, so "kg to ft lbs" has no single answer — you need a distance as well as a mass before the question is complete.

Why kg to litres, cups, or cubic metres needs density

Mass and volume are different dimensions, so no fixed factor connects them. What bridges the two is density, and density changes with the substance:

volume = mass ÷ density

Water is the only common case where the numbers look like a conversion: 1 kg of water is 1 litre, which is why the shortcut gets repeated so often. It is wrong for flour by nearly a factor of two.

"kg to cm" and "kg to feet" are not conversions

Kilograms measure mass and centimetres measure length — there is no factor between them, and any site offering one is guessing. Searches like this almost always mean one of two things:

• You have a height and a weight and want a single number. That number is BMI — use the BMI calculator, which takes both and returns one figure.
• You are reading a chart that lists a healthy weight for a height. Those charts are BMI tables printed in reverse, not conversions.

The same applies to kg to calories. Body tissue is not a unit of energy; the usual rule of thumb is that losing one kilogram of fat requires roughly a 7,700 kcal deficit, which is an estimate about metabolism, not a unit conversion. The calorie calculator works that out from your own numbers.

Pressure, energy, and power need more than a mass

A few conversions get asked for constantly and none of them are possible from a mass alone:

Converting body measurements for a health check? The BMI calculator accepts imperial units directly. For all other unit types, see the unit converter.