Convert lbs to kg

Pound

What Is a Pound?

The pound (symbol: lb) is a mass unit in both the British Imperial and U.S. customary systems. Today’s international avoirdupois pound is defined as exactly 0.45359237 kg and divides neatly into 16 ounces for practical fractional measurements.

Historical Background

The term “pound” traces back to the Roman libra. In medieval Europe, many local variants existed until the 13th-century adoption of the avoirdupois system standardized a 16-ounce pound—chosen because 16 splits evenly by 2, 4, and 8. That definition was internationally ratified in 1959.

Where It’s Used

In the United States, pounds remain the everyday standard for body weight, groceries, and commercial weighing. In the UK, metric units dominate official use, but pounds still appear on food labels and in personal-weight descriptions—often alongside “stones” (1 stone = 14 lb).

Kilogram

What Is a Kilogram?

A kilogram (symbol: kg) is the SI base unit of mass. Since May 20 2019, it’s defined by fixing Planck’s constant at 6.62607015 × 10⁻³⁴ J·s, with the metre and second tied to the speed of light and the cesium-133 frequency. This modern approach preserves the kilogram’s exact weight without relying on a physical artifact.

Historical Background

“Kilogram” comes from the French kilogramme—Greek kilo- (“thousand”) plus Latin gramma (“small weight”). Originally (1794) it was linked to the mass of one litre of water at freezing point, but that proved too imprecise. Until 2019, a platinum-iridium cylinder near Paris served as the standard, until tiny drifts prompted the switch to a constants-based definition.

Where It’s Used

Globally, the kilogram underpins virtually all mass measurements in science, industry, commerce, and everyday life—forming the foundation of weight systems around the world.

Pound → Kilogram Conversion Table

How to Convert

• 1 lb = 0.45359237 kg

• 1 kg = 2.20462262 lb

Example

To convert 15 lb into kilograms: