Conversion Calculators
Convert between units of length, area, speed, density, mass, weight, shoe sizes, and tire sizes with free online conversion calculators. Instant, accurate results for any measurement system.
Conversion Calculator
Convert between hundreds of units across length, weight, temperature, volume, and more.
Speed Calculator
Calculate speed, distance, or time and convert between mph, km/h, and other speed units.
Density Calculator
Calculate density, mass, or volume using the density formula with unit conversions.
Mass Calculator
Convert between mass units including kilograms, pounds, ounces, grams, and tons.
Weight Calculator
Convert weight between different units and calculate weight on other planets.
Inch Converter
Convert inches to centimeters, feet, meters, and other length units quickly.
Miles Converter
Convert miles to kilometers, meters, feet, yards, and other distance units.
Square Meter Calculator
Convert between square meters, square feet, acres, hectares, and other area units.
Shoe Size Conversion
Convert shoe sizes between US, UK, EU, and other international sizing systems.
Tire Size Calculator
Compare tire sizes, calculate overall diameter, and check speedometer accuracy for different tires.
About Conversion Calculators
Our conversion calculators cover the most commonly needed unit transformations across measurement systems worldwide. Whether you are converting between metric and imperial, comparing shoe sizes across countries, or understanding tire specifications, these tools provide instant and accurate results.
General Unit Converter handles temperature, volume, data storage, and time conversions with an intuitive interface. The specialized calculators for speed, density, mass, weight, length, and area provide comprehensive multi-unit conversion with all common units displayed simultaneously.
For practical everyday needs, the Shoe Size Converter maps between US, UK, EU, and Japanese sizing systems for men and women. The Tire Size Calculator decodes tire markings and calculates overall diameter, circumference, and revolutions per mile.
Special-purpose tools include the Inch Converter for quick imperial measurements, Miles Converter for distance conversions, and Square Meter Calculator for area unit transformations.
Frequently Asked Questions
What is the difference between mass and weight?
Mass measures the amount of matter in an object (measured in kilograms or pounds-mass), while weight is the force of gravity on that mass (measured in newtons or pounds-force). On Earth, a 1 kg mass weighs approximately 9.81 newtons. In everyday usage, people often use 'weight' to mean mass, but they are scientifically distinct concepts.
How do I convert between Celsius and Fahrenheit?
To convert Celsius to Fahrenheit, multiply by 9/5 and add 32. To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9. Key reference points: 0°C = 32°F (water freezes), 100°C = 212°F (water boils), 37°C = 98.6°F (body temperature).
What is the metric system versus the imperial system?
The metric system (SI) is a decimal-based system used by most of the world, with base units like meters, kilograms, and liters. The imperial system, primarily used in the United States, uses feet, pounds, and gallons. The metric system is easier for calculations because units scale by powers of 10.
How accurate are online unit converters?
Our converters use internationally standardized conversion factors with high precision. Results are accurate to multiple decimal places. For scientific or engineering applications requiring extreme precision, verify that the conversion factors used match your specific standards (NIST, ISO, etc.).
What is a nautical mile versus a regular mile?
A nautical mile equals 1,852 meters (approximately 1.151 statute miles or 6,076 feet). It was originally defined as one minute of arc of latitude along a meridian, making it particularly useful for maritime and aviation navigation. A statute (regular) mile equals 5,280 feet or 1,609.344 meters.