Weight Converter

Convert weight and mass units free online -- kilograms, pounds, ounces, stone, and more. Accurate standard conversion factors between metric and imperial systems.

Value

From

Browser only.

How to Use This Tool

Enter a valueThe weight amount you want to convert

Choose from and to unitsMetric or imperial weight units

See the converted resultUsing exact international conversion factors

Weight and Mass -- Used Interchangeably in Practice

Physics distinguishes mass (an intrinsic property) from weight (the force gravity exerts on that mass), but everyday language, recipes, shipping labels, and body weight discussions all use these terms interchangeably, which is the convention this converter follows for practical usability.

The Exact Standard Behind Pound-to-Kilogram Conversion

Since 1959, the pound has been internationally defined as exactly 453.59237 grams, a precise standard rather than a rounded approximation. This calculator uses that exact figure, ensuring accuracy at any scale from small culinary measurements to large industrial weights.

Stone -- A Regional Holdout

Most of the English-speaking world moved to pounds or kilograms for body weight, but the UK and Ireland still commonly use stone (14 pounds) in everyday conversation and even some official health contexts, which is why this converter includes it specifically for that regional use case.

Frequently Asked Questions

Strictly speaking, kilograms measure mass while weight is a force that varies with gravity, but in everyday usage (and on Earth's surface, where this calculator is intended to apply) these terms are used interchangeably, which is the convention this tool follows.

1 pound equals exactly 453.59237 grams by international agreement, a precisely defined standard rather than an approximation, ensuring accurate conversion regardless of magnitude.

Stone (14 pounds) remains commonly used for body weight specifically in the UK and Ireland, while most other English-speaking countries and the rest of the world use pounds or kilograms directly without the stone unit.

Yes, the underlying calculation uses standard floating-point precision suitable for anything from milligram-scale measurements to multi-ton industrial weights, converting accurately across that full range.

This reflects a different ambiguity -- fluid ounces (volume) and weight ounces (mass) are different measurements that happen to share a name, which is a common source of cooking conversion confusion separate from what this weight-specific converter addresses.