Unit Converter
Convert between different units of measurement
Unit Categories
Common Length Conversions
About Length
• The meter (m) is the base unit of length in the International System of Units (SI)
• 1 kilometer = 1,000 meters
• 1 mile = 1,609.344 meters
• 1 foot = 0.3048 meters
Complete Unit Conversion Guide
Metric vs. Imperial: A Brief History
The metric system (SI — Système International) was established during the French Revolution in 1795 to create a universal, decimal-based measurement system. It uses meters for length, kilograms for mass, and seconds for time. Today, virtually every country uses the metric system as its official measurement standard.
The imperial system, derived from English units, is still used primarily in the United States, Myanmar, and Liberia. It includes familiar units like feet, pounds, and Fahrenheit. Understanding both systems is essential for international travel, science, cooking, and commerce.
Essential Length Conversions
- 1 inch = 2.54 centimeters
- 1 foot = 30.48 centimeters (12 inches)
- 1 yard = 0.9144 meters (3 feet)
- 1 mile = 1.609 kilometers (5,280 feet)
- 1 meter = 3.281 feet (39.37 inches)
- 1 kilometer = 0.621 miles
Essential Weight Conversions
- 1 ounce = 28.35 grams
- 1 pound = 453.6 grams (16 ounces)
- 1 kilogram = 2.205 pounds
- 1 stone = 6.35 kilograms (14 pounds)
- 1 metric ton = 1,000 kilograms (2,205 lbs)
- 1 US ton = 907.2 kilograms (2,000 lbs)
Temperature Conversion Formulas
- °C to °F: (°C × 9/5) + 32
- °F to °C: (°F − 32) × 5/9
- °C to K: °C + 273.15
Key reference points: Water freezes at 0°C / 32°F and boils at 100°C / 212°F. Normal body temperature is approximately 37°C / 98.6°F.
Frequently Asked Questions
Why doesn't the US use the metric system?
The US actually passed the Metric Conversion Act in 1975, making metric the "preferred" system, but adoption was voluntary. Industry inertia, the cost of retooling, and cultural familiarity with imperial units have slowed the transition. However, US science, medicine, and military already use metric extensively.
What's the difference between mass and weight?
Mass is the amount of matter in an object (measured in kilograms), while weight is the gravitational force on that mass (measured in newtons). On the Moon, you'd weigh about 1/6 of your Earth weight, but your mass stays the same.
How do metric prefixes work?
Metric prefixes represent powers of 10: kilo- (1,000×), centi- (1/100), milli- (1/1,000), micro- (1/1,000,000). For example, 1 kilometer = 1,000 meters, and 1 millimeter = 0.001 meters. This decimal consistency is what makes the metric system so efficient.