The avoirdupois pound used in the U.S. and U.K. is defined exactly as 0.45359237 kilograms. Every other customary weight follows from it: an ounce is 1/16 lb (28.349523125 g), a stone is 14 lb, a U.S. short ton is 2,000 lb and a British long ton is 2,240 lb. So 150 lb is 68.04 kg, and 1 kg is about 2.20462 lb.
This converter uses those exact factors (NIST SP 811 lists the pound as 0.4535924 kg and the short ton as 907.1847 kg) and shows the result in every unit at once. Strictly these are units of mass; in everyday use "weight" means the same thing.
How to use the weight converter
- Enter the amount.
- Choose the unit you have and the unit you want.
- Read the result and the full table. For pounds and ounces, convert the ounces to a decimal first (8 oz = 0.5 lb).
Formula
Worked example
Convert 150 lb to kilograms, and 250 g to ounces.
- 150 × 0.45359237 = 68.0389 kg.
- 250 g ÷ 28.349523125 g/oz = 8.8185 oz.
- 11 st 6 lb = 160 lb = 72.57 kg.
Quick reference
| From | To | Multiply by |
|---|---|---|
| pounds | kilograms | 0.45359237 (exact) |
| kilograms | pounds | 2.20462 |
| ounces | grams | 28.3495 |
| grams | ounces | 0.035274 |
| stones | kilograms | 6.35029 |
| short tons | tonnes | 0.907185 |
Troy ounces (31.1035 g), used for precious metals, are a different unit and are not included here. NIST's kitchen guide rounds 1 oz to 28 g and 1 lb to 454 g for cooking. For recipes, see the cooking measurement converter. To compare prices per pound or per kilogram, use the unit price calculator.
Pounds and ounces to kilograms
Weights in the U.S. are often written as pounds and ounces (a baby at 7 lb 8 oz) and in the U.K. as stones and pounds (a person at 11 st 4 lb). To convert:
- Turn everything into one unit: 7 lb 8 oz = 7 + 8/16 = 7.5 lb; 11 st 4 lb = 11 × 14 + 4 = 158 lb.
- Multiply by 0.45359237: 7.5 lb = 3.402 kg; 158 lb = 71.67 kg.
Going the other way, multiply kilograms by 2.20462 to get pounds, then split off the whole pounds and multiply the remainder by 16 for ounces: 3.2 kg = 7.055 lb = 7 lb 0.9 oz.
Weight vs. mass
Kilograms, grams, pounds and ounces as used here are units of mass, the amount of matter in something. Strictly, weight is the force of gravity on that mass, measured in newtons, and it would be smaller on the Moon. In everyday life, and on scales, food labels and shipping forms, "weight" means mass, and this converter treats it that way.
Recipes and nutrition labels mix units: a nutrition label might list protein in grams while the package is sold in ounces. For grams of food in recipes, use the weight units here; for cups and spoons (which measure volume, not weight) use the cooking measurement converter.
Caveats and assumptions
- Avoirdupois units only; troy and apothecary units differ.
- Display limited to 10 significant digits.
Frequently asked questions
How many kilograms is 150 pounds?
68.04 kg (150 × 0.45359237).
How many pounds are in a kilogram?
About 2.20462 lb.
How many grams are in an ounce?
28.349523125 g exactly, often rounded to 28.35 g (or 28 g in recipes).
How many pounds is a stone?
14 pounds, or about 6.35 kg.
Is a ton the same as a tonne?
No. A U.S. short ton is 2,000 lb (907.2 kg), a U.K. long ton is 2,240 lb (1,016 kg) and a metric tonne is 1,000 kg (2,204.6 lb).
How do I convert kg to lbs?
Multiply by about 2.20462. 70 kg = 154.3 lb.
How many ounces are in a pound?
16 ounces.
Sources
- NIST SP 811 Appendix B.9 — Conversion factors — pound, ounce, short ton, long ton and tonne
- NIST — SI Units: Mass — the kilogram and metric mass units
- NIST Metric Kitchen — Cooking Measurement Equivalencies — rounded household equivalents (28 g, 454 g)
This calculator gives estimates for planning and education. Check measurements, local codes, supplier specs and your school's official policy before relying on a result. See our disclaimer and how we build and check calculators.