The world uses two major measurement systems: the metric system (used by 95% of the world) and the imperial/US customary system (used primarily in the United States).
The Metric System
Based on powers of 10, using meters, grams, and liters as base units. Created in France in the 1790s and adopted internationally.
- Length: mm, cm, m, km
- Weight: mg, g, kg
- Volume: mL, L
The Imperial System
Uses inches, feet, yards, miles for length; ounces, pounds, stones for weight; and fluid ounces, pints, gallons for volume.
Key Differences
- Metric uses base-10; Imperial uses irregular ratios (12 inches/foot, 3 feet/yard)
- Metric is standard in science, medicine, and most countries
- Imperial is used daily in the US, Liberia, and Myanmar