# Guide to the conversion calculators

The conversion calculators turn a value in one unit into another: temperature, speed, time, data storage, weight and mass, fractions and percentages, and amounts of money between currencies.

## Conversion

### [Currency Converter](https://www.calculator.land/calculators/currency-converter/)

Converts an amount between the euro and the other currencies in the European Central Bank's reference rates, and between two other currencies as a cross rate via the euro. It shows the result, the rate for one unit and the date of the reference rates it used, and a button swaps the two currencies.

### [Data Storage Converter](https://www.calculator.land/calculators/data-storage-converter/)

Converts between units of data: decimal units from bytes to yottabytes, binary units from kibibytes to yobibytes, bits from bits to exabits, and media such as a floppy disk, a CD, a DVD and a Blu-ray disc. It labels the result as a decimal, binary or bit unit, flags a conversion between the decimal and the binary system, and gives a sense of the size, such as roughly how many HD films, songs or photos it holds.

### [Fraction to Percentage Converter](https://www.calculator.land/calculators/fraction-to-percentage/)

Turns a fraction or a mixed number into a percentage, or a percentage into a fraction in its lowest terms. It shows the result with the number of decimals you choose, next to the simplified fraction, the decimal and the mixed number, writes out the steps and draws the share as a doughnut chart.

### [Precision Weight & Mass Converter](https://www.calculator.land/calculators/weight-mass-converter/)

Converts a weight or mass between kilograms, grams, milligrams, metric tonnes, pounds, ounces, stone, US short tons, UK long tons, carats and grains. You choose 0, 2 or 4 decimals or scientific notation, a button swaps the two units, and a line under the result gives the factor to multiply by.

### [Temperature Converter](https://www.calculator.land/calculators/temperature-converter/)

Converts a temperature between Celsius, Fahrenheit, Kelvin, Rankine and Réaumur: type a value into any of the five fields and the other four are filled in, rounded to two decimals. Six presets enter values such as body temperature, the boiling point of water and absolute zero, a note explains special values such as minus 40 degrees, where Celsius and Fahrenheit meet, and a value below absolute zero gives an error.

### [Time Converter](https://www.calculator.land/calculators/time-converter/)

Converts a value from any of twelve time units, from nanoseconds to centuries, and lists it in all twelve units at once, with the unit you started from highlighted. You choose the number of decimals, and each result can be copied.

### [Ultimate Speed Converter](https://www.calculator.land/calculators/speed-converter/)

Converts a speed between metres per second, kilometres per hour, miles per hour, knots, feet per second, Mach and the speed of light, with a choice of decimals, a swap button and three quick picks such as km/h to mph. It shows the conversion factor it used and compares the speed with everyday examples from walking pace to orbital velocity; Mach is taken as 340.3 m/s at sea level, and a speed above the speed of light gets a warning.