Convert pounds to kilograms with stones, ounces, grams output. Includes optional BMI calculator, body weight reference table, and visual weight bar.
This converter focuses on the most common everyday metric-imperial weight change: pounds to kilograms. One pound is defined as exactly 0.45359237 kilograms, so the underlying conversion is exact before rounding and presentation.
It also works in reverse and shows grams, ounces, and stone-plus-pounds notation alongside the main result. That makes it useful for body-weight tracking, forms, luggage checks, and any situation where the same value has to be reported in US, UK, and metric formats.
The optional BMI and reference sections add context, but the core job of the page is simple: turn pounds into a clean kilogram value quickly and accurately. That is useful when a US body-weight or luggage number needs to be restated in the metric format used by international forms, clinics, or travel rules. The extra outputs also help when the same number needs to be shown in kilograms, stones, and pounds without recalculating it separately.
Pounds are standard in the US, while kilograms are standard almost everywhere else. This converter bridges that gap directly and keeps the nearby units visible at the same time, so one input can be reused across forms, labels, luggage limits, and personal tracking logs. It is particularly useful when the same weight has to be reported in both US and metric systems without rounding twice.
Kilograms = Pounds × 0.45359237 Pounds = Kilograms ÷ 0.45359237 Stones = Pounds ÷ 14 BMI = kg ÷ (height in meters)²
Result: 68.04 kg | 10 st 10 lb | BMI 22.1 (Normal)
150 lbs × 0.45359237 = 68.04 kg. Divided by 14, that is 10 stones and 10 pounds. With a height of 5'9" (1.753 m), BMI = 68.04 ÷ 1.753² = 22.1, which falls in the normal weight category.
The pound has roots in the Roman "libra pondo" (a pound by weight), which is why its abbreviation is "lb." The kilogram was defined in 1799 as the mass of one liter of water at its densest temperature (4°C). In 2019, the kilogram was redefined in terms of the Planck constant, giving it a fundamental physics definition rather than a physical artifact.
The kilogram is the official mass unit in every country's legal metrology system, including the United States (where the pound is officially defined as exactly 0.45359237 kg). However, everyday use of pounds persists in the US, Myanmar, and Liberia. The UK uses a hybrid system—body weight in stones, food in grams, and some produce in pounds.
For fitness and health tracking, consistency matters more than the unit used. However, converting between systems is essential when following international fitness programs, consulting foreign medical references, or using equipment calibrated in a different system. This converter ensures accurate, instant translation between all major weight units.
Exactly 0.45359237 kg. For rough mental math, multiply pounds by 0.45 or divide by 2.2 when you only need a quick estimate.
Divide by 2.2 for an approximation. For example, 200 lbs ÷ 2.2 is about 90.9 kg, while the exact value is 90.72 kg.
The UK and Ireland traditionally measure body weight in stones and pounds. One stone equals 14 pounds, and that system still persists for personal weight even though the country officially uses metric units.
Yes. One pound is defined as exactly 0.45359237 kg, so the underlying conversion is fixed. Any difference you see comes only from display rounding.
Healthy weight depends on height, so BMI is usually the better reference than a single kilogram number. A BMI of 18.5–24.9 is considered normal, and for a person 170 cm tall that is roughly 53–72 kg.
Consumer digital scales are typically accurate to about ±0.2 kg (±0.5 lb). Mechanical scales can be off by 1–2 lb, so weighing at the same time daily on the same scale is the best way to compare readings.