Unit Converter

How Unit Converter Works

This tool converts a value between units within eight categories -- length, weight/mass, temperature, volume, area, speed, time, and digital storage -- instantly as you type, with a one-click swap between the "from" and "to" units.

Formula & Method

For every category except temperature, each unit is defined by a factor relative to that category's base unit (for example, meters is the length base with factor 1, and a kilometer's factor is 1000). Converting is then a single multiplication: result = amount × fromFactor ÷ toFactor. Temperature is handled separately since Celsius, Fahrenheit, and Kelvin relate by addition and scaling rather than a simple ratio -- the tool converts the input to Celsius first ((F−32)×5/9 for Fahrenheit, K−273.15 for Kelvin), then converts from Celsius to the target unit. Displayed results use adaptive precision: 6 decimal places for results under 1, 4 for results under 100, 2 for results under 10,000, and none for larger results, so both very small and very large conversions stay readable.

Worked Example

Converting 10 kilometers to miles (factors 1000 and 1609.344) gives 6.2137 mi. Converting 5 kilograms to pounds (factors 1 and 0.45359237) gives 11.0231 lb. Converting 100°C to Fahrenheit gives 212°F, using the Celsius-as-intermediate temperature formula.

Frequently Asked Questions

Why is temperature converted differently from the other categories?

Length, weight, and the other categories are all simple ratios of each other (multiply by a factor), but Celsius, Fahrenheit, and Kelvin have different zero points, so converting between them requires addition/subtraction as well as scaling. The tool converts through Celsius as a common intermediate step.

Which gallon, quart, cup, and fluid ounce does this use?

The volume category uses US customary units (US gallon, US quart, US pint, US cup, US fluid ounce), not UK/imperial units, which are a different size. If you need imperial volume units, be aware the values won't match this tool's conversions.

Why do very small or very large results show a different number of decimal places?

The tool uses adaptive precision so results stay meaningful across huge ranges of scale (millimeters to kilometers, bytes to terabytes) -- smaller results get more decimal places so they aren't rounded to zero, while larger results get fewer so they aren't cluttered with insignificant digits.

Are digital storage units calculated in powers of 1000 or 1024?

This tool uses powers of 1024 (1 KB = 1024 bytes, 1 MB = 1024 KB, and so on) -- the binary convention historically used by operating systems -- rather than the decimal (powers of 1000) convention some storage manufacturers use, so results may differ slightly from a drive's advertised capacity.