Unit Converter
Convert between units of length, weight, temperature, speed, and more.
Safe conversion with no data sent to server
Last updated: March 2026
0.001 km
All Conversions from 1 m
What Is Unit Conversion?
Unit conversion is the process of expressing a measurement in a different unit while preserving the same quantity. Every physical measurement — length, weight, temperature, speed, volume — can be expressed in multiple unit systems. Converting between them accurately is essential for science, engineering, cooking, travel, and everyday calculations.
The two dominant measurement systems in the world are the International System of Units (SI), commonly called the metric system (used by most of the world), and the Imperial/US Customary system (used primarily in the United States). Our unit converter supports seamless conversion between both systems across dozens of unit types.
Supported Unit Categories
This converter supports the most commonly needed unit categories:
- Length: millimeters, centimeters, meters, kilometers, inches, feet, yards, miles, nautical miles
- Weight/Mass: milligrams, grams, kilograms, metric tons, ounces, pounds, stone, US tons
- Temperature: Celsius, Fahrenheit, Kelvin — with proper formula-based conversions (not just ratios)
- Speed: meters per second, kilometers per hour, miles per hour, knots, feet per second
- Volume: milliliters, liters, cubic meters, teaspoons, tablespoons, cups, pints, quarts, gallons
- Area: square centimeters, square meters, hectares, square kilometers, square inches, square feet, acres, square miles
Common Unit Conversions Reference
Quick reference for the most frequently needed conversions:
Length
- 1 inch = 2.54 cm
- 1 foot = 0.3048 meters
- 1 mile = 1.60934 km
- 1 meter = 3.28084 feet
Weight
- 1 pound = 0.453592 kg
- 1 kilogram = 2.20462 lbs
- 1 ounce = 28.3495 grams
- 1 stone = 6.35029 kg
Temperature
- °F = (°C × 9/5) + 32
- °C = (°F − 32) × 5/9
- K = °C + 273.15
Speed
- 1 mph = 1.60934 km/h
- 1 km/h = 0.621371 mph
- 1 knot = 1.852 km/h
FAQ
Why are temperature conversions different from other unit conversions?
Most unit conversions use simple multiplication (e.g., multiply meters by 3.28084 to get feet). Temperature conversions require both multiplication and addition because the Celsius and Fahrenheit scales have different zero points. Zero Fahrenheit is not the same as zero Celsius — they are offset scales, not proportional ones. Kelvin, however, is a true absolute scale where 0 K is absolute zero.
What is the difference between weight and mass?
Scientifically, mass measures the amount of matter in an object (kilograms, grams), while weight measures gravitational force on that mass (newtons). In everyday usage, "weight" typically refers to mass measured in a gravitational field. Our weight converter uses mass units, which remain constant regardless of gravity.
How accurate are the conversions?
All conversions use standard, internationally recognized conversion factors. Results are displayed to up to 8 significant decimal places. For most practical applications, this level of precision far exceeds what is needed. Scientific or engineering applications requiring extreme precision should use dedicated reference materials.
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