About the Pounds to kg Calculator
Pounds are how weight is given on American scales, recipes, product labels and fitness apps, and how many British people still state body weight alongside stone. Kilograms are what doctors, airlines, gyms and most of the world use. Converting pounds to kilograms is needed for medical forms, dosing, baggage limits, shipping, recipes and training programmes written in metric units.
This pounds to kg calculator converts pounds, or pounds and ounces together, to kilograms exactly. It also shows the weight in grams, the total in pounds or ounces, and in stone. Entering pounds and ounces separately makes it simple to convert a baby's birth weight such as 7 lb 8 oz.
How to Use the Pounds to kg Calculator
Enter the pounds.
If the weight includes ounces, enter them in the ounces field. Leave it at zero otherwise.
The kilograms appear straight away, with grams, the total and stone.
The Formula
total pounds = pounds + ounces ÷ 16
kilograms = total pounds × 0.45359237
grams = kilograms × 1,000A pound is exactly 0.45359237 kilograms by international definition, and there are 16 ounces in a pound, so the whole calculation is exact until the result is rounded for display.
Step-by-Step Example
150 pounds to kilograms.
150 × 0.45359237 = 68.0389 kgSo 150 lb is 68.0389 kg, or 68,038.9 grams — about 10 stone 10 pounds.
A baby weighing 7 lb 8 oz.
Total pounds: 7 + 8 ÷ 16 = 7.5 lb
Kilograms: 7.5 × 0.45359237 = 3.40194 kgThe baby weighs 3.40194 kg, about 3,402 grams.
Quick Reference
These conversions cover the most common weights, from a single pound up to typical adult body weights:
1 lb = 0.453592 kg = 453.592 g
10 lb = 4.53592 kg
50 lb = 22.6796 kg
100 lb = 45.3592 kg
150 lb = 68.0389 kg
200 lb = 90.7185 kg
250 lb = 113.398 kgThe Halve-and-Subtract Rule
A quick mental method is to halve the pounds and subtract a tenth of that half. For 150 lb: half is 75, a tenth of that is 7.5, and 75 − 7.5 = 67.5 kg, within about 1 percent of the exact 68.04. For a closer answer, multiply by 0.45: 150 × 0.45 = 67.5, the same figure, or by 0.4536 for near-exact results.
Pounds and Ounces
Ounces are sixteenths of a pound, not tenths, which is why 7 lb 8 oz is 7.5 lb and not 7.8 lb. Other common fractions: 4 oz is a quarter pound (0.25 lb, 113.4 g), 12 oz is three quarters (0.75 lb, 340.2 g). Entering pounds and ounces separately lets the calculator handle this correctly.
Medical and Health Uses
Hospitals and pharmacies record weight in kilograms because medicine doses, fluid volumes and body mass index are calculated per kilogram. A patient who gives their weight as 180 lb weighs 81.6466 kg. Because a pound-for-kilogram mix-up can double or halve a calculated dose, medical staff convert with the exact factor and write the kilogram figure clearly.
Shipping, Travel and Sport
Couriers, postal services and airlines outside the US price and limit by kilograms. A 50 lb suitcase is 22.6796 kg, just under the common 23 kg allowance. Weightlifting programmes and competitions use kilograms: a 225 lb lift is about 102.1 kg, and a 315 lb lift about 142.9 kg.
Cooking With Pound Measurements
American recipes often list meat, butter, cheese and produce by the pound, while metric kitchens weigh in grams. A pound of minced beef is 453.6 g, usually bought as a 500 g pack; half a pound of butter, two US sticks, is 226.8 g. Roasting times in American recipes are often given in minutes per pound, so convert the joint's weight to pounds, or the time to minutes per kilogram, by multiplying by 2.20462: 20 minutes per pound is about 44 minutes per kilogram. For baking, weigh in grams where you can, since it is more precise than converted cup measures.
Body Weight in Pounds, Stone and Kilograms
In Britain, body weight is often given in stone and pounds, such as 11 st 6 lb. To convert that, multiply the stone by 14 and add the pounds — 11 × 14 + 6 = 160 lb — then convert the pounds: 160 lb is 72.5748 kg. Fitness apps and smart scales can usually display any of the three units, but medical records, prescriptions and international studies use kilograms, so it is worth knowing your weight in kilograms as well.
Understanding Your Result
The headline is the weight in kilograms.
The grams line gives the same weight in grams.
The total line shows pounds and ounces combined as decimal pounds, or the total ounces for a weight in pounds only.
The stone line gives the weight in stone as a decimal.
When Should You Use This Calculator?
Use it for medical forms, dosing and health records that require kilograms.
Use it for baby weights in pounds and ounces.
Use it for shipping and baggage allowances in kilograms.
Use it for gym training, weight classes and recipes written in metric units.
Common Mistakes
Treating ounces as decimals. 7 lb 8 oz is 7.5 lb, not 7.8 lb.
Dividing by 2.2 with rounding. It is close, but use 0.45359237 for exact results.
Entering stone as pounds. Convert stone to pounds first: 1 st = 14 lb, so 11 st is 154 lb.
Mixing up fluid ounces and ounces. Fluid ounces are volume, not weight, so they cannot be converted to kilograms without knowing the density.
Rounding the kilograms too early. Keep the exact figure for dosing and records, and round only when reporting the final value.