Unit Conversion Guide: Metric to Imperial Made Simple

Two measurement systems exist in the world — metric and imperial — and knowing how to convert between them is an essential everyday skill.

Why do two systems exist?

The metric system (International System of Units, SI) was developed in France in the late 1700s and adopted by almost every country as the official standard.

The imperial system originated in Britain and remains in everyday use in the United States. South Africa, Australia and Canada officially use metric though some imperial references persist.

Length and distance conversions

• 1 kilometre = 0.621 miles
• 1 mile = 1.609 kilometres

Quick reference for runners: 5K = 3.1 miles, 10K = 6.2 miles, Marathon = 42.2km = 26.2 miles

Weight conversions

• 1 kilogram = 2.205 pounds
• 1 pound = 0.454 kilograms

Volume conversions

• 1 litre = 4.227 US cups
• 1 US gallon = 3.785 litres

Area conversions

• 1 square metre = 10.764 square feet
• 1 hectare = 2.471 acres

Frequently asked questions

Why does the US use imperial and not metric? Despite several attempts, the US has never fully transitioned to metric.

Does South Africa use metric or imperial? South Africa officially uses metric.

What is the easiest way to convert km to miles? Multiply km by 0.621.