Unit Converter

Convert between 220+ units across 20 categories including length, mass, temperature, volume, speed, and digital storage. Instant reactive conversion as you type.

Converter
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How to Use

  1. 1
    Select a category

    Choose from 20 unit categories like Length, Mass, Temperature, Volume, or Digital Storage using the category dropdown.

  2. 2
    Pick units

    Select the source and target units from the dropdown menus. Use the swap button to quickly reverse the conversion direction.

  3. 3
    Enter a value

    Type a number and see the converted result instantly. No need to click a button — the conversion updates reactively as you type.

About

Unit conversion is the process of expressing a quantity in different units of measurement while preserving its actual value. The need for standardized conversion arose from millennia of diverse measurement systems — the Egyptian royal cubit, Roman foot, Chinese chi, and countless local standards.

The metric system, introduced during the French Revolution in 1795, was the first attempt at a universal measurement standard. It used decimal prefixes (kilo-, centi-, milli-) based on powers of 10, making arithmetic straightforward. The meter was originally defined as one ten-millionth of the distance from the North Pole to the equator.

Today, the International System of Units (SI), adopted in 1960, is the world's most widely used measurement system. Only the United States, Myanmar, and Liberia have not officially adopted the metric system for everyday use, though even these countries use SI units in science and medicine.

Unit conversion follows a simple principle: multiply by the ratio of the target unit to the source unit. For linear units, this is a single multiplication. Temperature is the notable exception — Celsius, Fahrenheit, and Kelvin use different zero points and scale factors, requiring formulas rather than simple ratios. This converter handles all these cases, including the special temperature formulas.

FAQ

How does temperature conversion work?
Temperature conversions use non-linear formulas, unlike other units which use simple multiplication. Celsius to Fahrenheit: °F = (°C × 9/5) + 32. Celsius to Kelvin: K = °C + 273.15. Fahrenheit to Celsius: °C = (°F − 32) × 5/9.
What is the SI system?
The International System of Units (SI) is the modern metric system used by most countries. Its seven base units are: meter (length), kilogram (mass), second (time), ampere (electric current), kelvin (temperature), mole (amount of substance), and candela (luminous intensity). All other units are derived from these.
Why are there different gallon sizes?
The US gallon (3.785 liters) and Imperial gallon (4.546 liters) evolved from different historical standards. The US gallon is based on the English wine gallon of 1707, while the Imperial gallon was standardized in 1824 based on the volume of 10 pounds of water at 62°F.
Is a kilobyte 1000 or 1024 bytes?
Historically, a kilobyte meant 1,024 bytes (2¹⁰) in computing. The IEC standard introduced kibibyte (KiB) for 1,024 bytes and reserved kilobyte (KB) for exactly 1,000 bytes. This converter uses standard decimal (1 KB = 1,000 bytes) and binary (1 KiB = 1,024 bytes) units separately for precision.
How accurate are the conversions?
All conversion factors use high-precision values from NIST (National Institute of Standards and Technology). Results are displayed with up to 10 significant digits. For scientific work requiring extreme precision, consult the NIST reference directly.

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