Korea follows the International System of Units (SI, Metric System), while the United States and the United Kingdom use Imperial and U.S. Customary Units. This difference exists due to historical, international standardization, and economic reasons.
Metric System vs. Imperial System
✅ Korea: Metric System (SI Units)
Metric System Used in Korea:
Length: Meters (m), Kilometers (km) | Weight: Kilograms (kg), Grams (g) | Volume: Liters (L), Milliliters (mL) | Temperature: Celsius (°C)
Length: Meters (m), Kilometers (km) | Weight: Kilograms (kg), Grams (g) | Volume: Liters (L), Milliliters (mL) | Temperature: Celsius (°C)
- Length: Meters (m), Kilometers (km)
- Weight: Kilograms (kg), Grams (g)
- Volume: Liters (L), Milliliters (mL)
- Speed: Kilometers per hour (km/h)
- Temperature: Celsius (°C)
Historical Background: How Did the Differences Develop?
📌 The Origin of the Imperial System
- The Imperial System was officially adopted by the British monarchy in the 12th century.
- During the Industrial Revolution, British influence spread this system worldwide.
- The U.S., a former British colony, maintained this system after independence.
📌 Korea's Transition to the Metric System
- Before the 20th century, Korea used traditional units such as cheok (尺), geun (斤), and ri (里).
- In 1894, Korea introduced the metric system during the Gabo Reform but used both systems simultaneously.
- During the Japanese colonial period (1910–1945), Korea gradually adopted the metric system.
- In 1961, Korea officially enforced the metric system through the Measurement Act, phasing out traditional units.
Why Didn’t the U.S. Switch to the Metric System?
Reasons the U.S. Did Not Adopt the Metric System:
High conversion costs | Cultural resistance | Existing industries reliant on Imperial units | Military and space technology compatibility
High conversion costs | Cultural resistance | Existing industries reliant on Imperial units | Military and space technology compatibility
- Economic Costs: Changing road signs, manufacturing systems, and everyday usage would cost billions of dollars.
- Cultural Resistance: Americans are accustomed to inches, pounds, and miles, making a shift unpopular.
- Industrial Challenges: Many American businesses and factories are built around Imperial units.
- Military and Space Technology: The U.S. military and NASA have standardized equipment in Imperial units.
📌 Conclusion: Why Are Korea and the U.S. Different?
| Category | Korea (Metric System) | U.S. (Imperial System) | U.K. (Mixed Usage) |
|---|---|---|---|
| Length | Meters (m), Kilometers (km) | Feet (ft), Miles (mile) | Miles (mile), Meters (m) |
| Weight | Kilograms (kg), Grams (g) | Pounds (lb), Ounces (oz) | Pounds (lb), Kilograms (kg) |
| Volume | Liters (L) | Gallons (gal), Pints (pt) | Gallons (gal), Liters (L) |
| Temperature | Celsius (°C) | Fahrenheit (°F) | Celsius (°C) |
Ultimately, Korea adopted the metric system due to international trade, ease of calculations, and government regulations, while the U.S. retained its system due to cost, cultural familiarity, and industrial dependency. The U.K. remains in between, using a mix of both.
