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Converters

Two general-purpose converters live here: a unit converter covering eight families of measurement, and a currency converter that uses the European Central Bank official daily reference rates. Number bases, Roman numerals and color formats are conversions too, and those sit in the developer and generator hubs.

Unit Converter

Convert length, mass, volume, area, speed, data, time and temperature units instantly.

Private · in-browser

Currency Converter

Convert between world currencies using live exchange rates.

Private · in-browser

Which converter do I need?

The unit converter handles eight measurement families: length, mass, volume, area, speed, digital storage, time and temperature. The currency converter handles money, fetching a published rate for the pair you pick rather than using a table baked into the page.

Three more conversions live under other hubs, because that is where people look for them:

What the exchange rates are, and are not

The currency converter uses the European Central Bank’s euro reference rates, retrieved on demand from the free frankfurter.app service. These are official figures, which is exactly why they are not live market ticks: the ECB publishes them once per working day, so the same rate holds all day and the last published rate carries over across weekends and holidays. They also carry no bid-ask spread, so a bank, card or exchange bureau will always hand you a slightly worse number than the reference rate. Use it to understand what an amount is worth, not to predict what a transfer will cost. Only currencies on the ECB list are available.

Unit conversions that catch people out

Volumes are US customary: the gallon is 3.785 liters, the quart 0.946 liters and the cup 236.588 ml. The UK imperial gallon of about 4.546 liters is a different unit and is not included, so British fuel-economy and older recipe figures will not line up.

Digital storage uses binary factors, so 1 KB is 1,024 bytes and 1 MB is 1,048,576 bytes — the convention operating systems traditionally report. Drive manufacturers advertise decimal units, which is the entire reason a "1 TB" disk shows up smaller in your file manager.

Temperature is the odd one out. Celsius, Fahrenheit and Kelvin are converted through an offset and a scale rather than a single multiplier, because their zero points differ. That also means ratios are meaningless: 20 °C is not twice as warm as 10 °C. Mass uses the metric tonne of 1,000 kg, not the US short ton.

Frequently asked questions

Where do the exchange rates come from and how often do they change?
From the European Central Bank euro reference rates, retrieved through the free frankfurter.app API. The ECB publishes them once per working day, so the figure updates daily rather than continuously, and on weekends and public holidays the last published rate carries over unchanged.
Why does my bank give me a worse rate than this?
A reference rate is a mid-market figure with no margin built in. Banks, cards and bureaux quote a spread around it and often add a transfer or conversion fee, so the amount you receive is lower. Treat the converter output as the benchmark to compare a quoted rate against, not as the price you will be charged.
Are the gallons and cups US or imperial?
US customary throughout — a 3.785-liter gallon, a 0.946-liter quart and a 236.588 ml cup. The UK imperial gallon is about 4.546 liters and is not offered, so converting British fuel consumption or a pre-metric British recipe with these units will give you the wrong answer.
Why does the converter say 1 MB is 1,048,576 bytes?
Because the data category uses binary multiples of 1,024, matching how operating systems have traditionally reported file and disk sizes. Storage manufacturers use decimal multiples of 1,000, which is why a drive sold as 1 TB appears as roughly 931 GB in a file manager. Neither figure is wrong; they are different conventions.
Why is temperature handled differently from other units?
Because it is not a simple ratio. Length or mass conversions multiply by one factor, but temperature scales have different zero points, so converting requires shifting and scaling. That is also why comparisons like twice as hot make no sense in Celsius or Fahrenheit — only Kelvin, which starts at absolute zero, supports them.