Lbs to Kg Converter

One pound (lb) is exactly equal to 0.45359237 kilograms. This is the internationally defined value. Rounded for practical use: 1 lb ≈ 0.454 kg. Conversely, 1 kilogram = approximately 2.20462 pounds. The pound is a unit from the imperial system, historically based on the weight of 7,000 grains (troy weight). The metric kilogram is defined in terms of the Planck constant since 2019, replacing the physical prototype kilogram.

Divide the pounds by 2.2 for a quick mental estimate. This is accurate to within about 0.2%. Examples: 100 lbs ÷ 2.2 ≈ 45.5 kg (exact: 45.4 kg). 160 lbs ÷ 2.2 ≈ 72.7 kg (exact: 72.6 kg). 200 lbs ÷ 2.2 ≈ 90.9 kg (exact: 90.7 kg). For greater precision, use the exact factor: multiply lbs by 0.4536.

150 pounds = 68.0 kg (exactly 68.0389 kg). At 150 lbs, a person would have a BMI of 26.6 if they are 5'6" (168 cm) tall — slightly above the 'normal weight' range of 18.5–24.9. BMI is calculated as weight(kg) / height(m)². Most international health systems and medical forms use kilograms as the standard unit for body weight.

200 pounds = 90.7 kg (exactly 90.718 kg). This is a common milestone weight in fitness and health tracking. 200 lbs is often discussed in strength training as a threshold (lifting '2 plates' per side on a barbell = 225 lbs / 102 kg). At 200 lbs, a 6-foot (183 cm) person has a BMI of 27.1 — classified as 'overweight' by WHO standards (BMI 25–29.9).

The US uses the imperial/customary system — including pounds for weight — because the country standardized its weights and measures before the metric system was fully established in the early 19th century. Despite several attempts to convert (including a Metric Conversion Act in 1975), the US has never mandated metric use in everyday life. Science, medicine, nutrition, and many industries in the US do use metric units, but everyday body weight and food packaging often still use pounds and ounces.