Weight to Kilograms Converter
Free Weight kilograms Converter for human metrics units. Enter a value to see equivalent measurements across systems.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator
Weight to Kilograms Converter
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Formula: kg = lb x 0.45359237 | kg = oz x 0.028349523 | kg = st x 6.35029318 | kg = g / 1000
Worked example — 175 lb = 79.3787 kg = 12 st 7 lb
Formula
kg = lb x 0.45359237 | kg = oz x 0.028349523 | kg = st x 6.35029318 | kg = g / 1000
All conversions go through grams as the base unit. Each input unit has an exact conversion factor to grams. Kilograms are then derived by dividing grams by 1000. The pound to kilogram factor (0.45359237) is an exact definition established by international agreement.
Worked Examples
Example 1: Body Weight Conversion
Problem:Convert 175 pounds to kilograms and stone.
Solution:Kilograms: 175 x 0.45359237 = 79.3787 kg Stone: 175 / 14 = 12 stone 7 pounds Ounces: 175 x 16 = 2,800 oz Grams: 175 x 453.59237 = 79,378.66 g
Result:175 lb = 79.3787 kg = 12 st 7 lb
Example 2: Shipping Package Weight
Problem:Convert 5.5 kilograms to pounds and ounces for a shipping label.
Solution:Pounds: 5.5 x 2.20462 = 12.1254 lb Whole pounds: 12 lb Remaining ounces: 0.1254 x 16 = 2.0064 oz Total ounces: 5.5 x 35.274 = 194.007 oz
Result:5.5 kg = 12 lb 2 oz = 194.01 oz
Frequently Asked Questions
How do I convert pounds to kilograms?
Multiply the weight in pounds by 0.45359237 to get kilograms. This conversion factor is exact by definition: one pound avoirdupois equals exactly 0.45359237 kilograms. For a quick mental estimate, divide pounds by 2.2. So 150 pounds is approximately 150 / 2.2 = 68.18 kg (exact: 68.0389 kg). The inverse conversion multiplies kilograms by 2.20462262 to get pounds.
What is the difference between avoirdupois and troy weight systems?
The avoirdupois system is used for everyday weighing: 1 pound = 16 ounces = 453.59 grams. The troy system is used for precious metals: 1 troy pound = 12 troy ounces, where 1 troy ounce = 31.1035 grams. A troy ounce is heavier than an avoirdupois ounce, but a troy pound is lighter than an avoirdupois pound. When someone says an ounce of gold, they mean a troy ounce (31.1 g), not an avoirdupois ounce (28.35 g). This converter uses the avoirdupois system unless otherwise noted.
Why is the kilogram the SI base unit of mass?
The kilogram was redefined in 2019 based on the Planck constant, making it independent of any physical artifact. Previously, it was defined by a platinum-iridium cylinder kept in Paris since 1889. The kilogram is the only SI base unit with a prefix (kilo-) in its name, a historical quirk from the French Revolution when the gram was too small for practical commerce. All other mass units in the SI system are derived from the kilogram: 1 milligram = 0.000001 kg, 1 metric ton = 1000 kg.
What is the difference between mass and weight?
Mass measures the amount of matter in an object (kilograms) and is constant everywhere. Weight is the gravitational force on that mass (newtons) and varies by location. On Earth, a 1 kg object weighs about 9.8 newtons. In everyday use, the terms are often used interchangeably.
References
Reviewed for accuracy by Manoj Kumar, Mathematics Educator · Editorial policy
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