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Unit Converter

Convert between units of length, weight, temperature, area, volume, speed, and data storage.

Unit Converter

Convert between units of length, weight, temperature, area, volume, speed, and data.

3.280839895

About Unit Conversion

Unit conversion is the process of expressing a quantity in different units of measurement. Whether you are converting kilometers to miles, kilograms to pounds, or Celsius to Fahrenheit, the underlying process involves multiplying or dividing by a conversion factor that relates the two units.

Metric vs. Imperial Systems

The world primarily uses two measurement systems:

  • Metric (SI): Used by most countries worldwide. Based on powers of 10, making conversions straightforward (1 km = 1,000 m, 1 kg = 1,000 g). The base units are meters, kilograms, seconds, and Celsius.
  • Imperial/US Customary: Used primarily in the United States, and partially in the UK and a few other countries. Uses units like inches, feet, miles, ounces, pounds, and Fahrenheit. Conversion factors are less intuitive (1 mile = 5,280 feet, 1 pound = 16 ounces).

Only three countries have not officially adopted the metric system: the United States, Myanmar, and Liberia. However, even in these countries, metric units are used in scientific and medical contexts.

Temperature Conversion

Temperature conversion is unique because it involves both multiplication and addition, unlike most unit conversions which are purely multiplicative:

  • Celsius to Fahrenheit: F = C x 9/5 + 32
  • Fahrenheit to Celsius: C = (F - 32) x 5/9
  • Celsius to Kelvin: K = C + 273.15

Key reference points: water freezes at 0°C (32°F, 273.15K) and boils at 100°C (212°F, 373.15K). Normal body temperature is approximately 37°C (98.6°F). Absolute zero, the coldest possible temperature, is -273.15°C (0K, -459.67°F).

Data Storage Units

Digital storage uses a binary system where each step is a factor of 1,024 (2^10):

  • 1 KB (kilobyte) = 1,024 bytes
  • 1 MB (megabyte) = 1,024 KB = 1,048,576 bytes
  • 1 GB (gigabyte) = 1,024 MB
  • 1 TB (terabyte) = 1,024 GB
  • 1 PB (petabyte) = 1,024 TB

Note that hard drive manufacturers often use the SI definition where 1 KB = 1,000 bytes, which is why a "1 TB" drive shows less than 1 TB in your operating system. This tool uses the binary (1,024) standard used by operating systems.

Frequently Asked Questions

Why does the US still use the imperial system?
The US attempted to switch to metric in the 1970s with the Metric Conversion Act of 1975, but the transition was voluntary and never gained sufficient momentum. The cost of changing road signs, manufacturing standards, and consumer expectations was deemed too high. Today, US industries like science, medicine, and the military use metric, while everyday life remains largely imperial. The UK uses a mix of both systems.
How do I convert between kilometers and miles?
1 mile equals approximately 1.609 kilometers. To convert miles to kilometers, multiply by 1.609. To convert kilometers to miles, divide by 1.609 (or multiply by 0.6214). A quick mental trick: multiply kilometers by 0.6 for a rough estimate in miles. For example, 100 km is roughly 60 miles (actual: 62.14 miles).
What is the difference between a US gallon and an Imperial gallon?
A US gallon equals 3.785 liters, while an Imperial gallon (used in the UK) equals 4.546 liters. This means an Imperial gallon is about 20% larger than a US gallon. This tool uses US gallons. When comparing fuel economy between countries, be aware of which gallon is being used, as "miles per gallon" will differ significantly.
Why are there 1,024 bytes in a kilobyte instead of 1,000?
Computers operate in binary (base 2), and 2^10 = 1,024 is the power of 2 closest to 1,000. Historically, "kilo" in computing meant 1,024. To reduce confusion, the IEC introduced distinct prefixes: kibibyte (KiB) for 1,024 bytes and kilobyte (KB) for 1,000 bytes. However, most operating systems and this tool still use the binary definition where 1 KB = 1,024 bytes.

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