Metric vs Imperial: A Complete Measurement Conversion Guide
Everything you need to know about metric and imperial measurement systems. Learn the history, differences, and how to convert between them easily.
Two Systems, One World
Despite living in an increasingly connected world, we still use two different measurement systems: metric and imperial. This guide explains both systems, their history, and how to convert between them.
The Metric System
Overview
The metric system (also called SI - International System of Units) is used by most of the world. It's based on powers of 10, making calculations straightforward.
Base Units
| Measurement | Unit | Symbol | |
| Length | Meter | m | |
| Mass | Kilogram | kg | |
| Time | Second | s | |
| Temperature | Kelvin/Celsius | K/°C | |
| Volume | Liter | L | |
| Prefix | Symbol | Factor | Example |
| Kilo | k | 1,000 | Kilometer (km) |
| Hecto | h | 100 | Hectare (ha) |
| Deca | da | 10 | Decagram |
| (base) | - | 1 | Meter, Gram, Liter |
| Deci | d | 0.1 | Decimeter |
| Centi | c | 0.01 | Centimeter (cm) |
| Milli | m | 0.001 | Millimeter (mm) |
| From | To | Multiply by | |
| Inches | Centimeters | 2.54 | |
| Feet | Meters | 0.3048 | |
| Miles | Kilometers | 1.609 | |
| Centimeters | Inches | 0.3937 | |
| Meters | Feet | 3.281 | |
| Kilometers | Miles | 0.6214 | |
| From | To | Multiply by | |
| Ounces | Grams | 28.35 | |
| Pounds | Kilograms | 0.4536 | |
| Grams | Ounces | 0.03527 | |
| Kilograms | Pounds | 2.205 | |
| From | To | Multiply by | |
| Fluid oz | Milliliters | 29.57 | |
| Cups | Milliliters | 236.6 | |
| Gallons (US) | Liters | 3.785 | |
| Liters | Gallons (US) | 0.2642 | |
| Celsius | Fahrenheit | Description | |
| 0°C | 32°F | Water freezes | |
| 20°C | 68°F | Room temperature | |
| 37°C | 98.6°F | Body temperature | |
| 100°C | 212°F | Water boils |
Practical Applications
Cooking
US recipes use cups, tablespoons, and Fahrenheit, while most other countries use grams, milliliters, and Celsius.
Common cooking conversions:
Travel
Understanding both systems helps when:
Health
Why the US Still Uses Imperial
The United States attempted metrication in the 1970s but it wasn't mandatory, leading to inconsistent adoption. Reasons for continued imperial use include:
Interestingly, US science, military, and medicine largely use metric.
Tips for Converting Mentally
Length
Weight
Temperature
Conclusion
Whether you're traveling, cooking, or working internationally, understanding both measurement systems is valuable. While metric is simpler mathematically, imperial remains common in daily life for millions of people.
Use our unit converter to quickly convert between any units in both systems.
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