Type a temperature in any of the five rows and press Convert beside it: the other four show the same temperature in Celsius, Fahrenheit, Kelvin, Rankine and Réaumur.
Runs locally in your browserEnter a number in the row of the scale you have and press Convert beside it. The other four rows are filled with the same temperature in Celsius, Fahrenheit, Kelvin, Rankine and Réaumur, and any of the five rows can be the starting point.
The conversion runs in the browser and nothing is uploaded. A point or a comma may be used for decimals, a minus sign is accepted for values below zero, and the line under the fields reports an entry that cannot be read.
Celsius and Fahrenheit are the everyday scales: water freezes at 0 °C and boils at 100 °C at sea level, which is 32 °F and 212 °F. Kelvin starts at absolute zero and uses the Celsius step, so 0 °C is 273.15 K. Rankine is the unit of the same absolute scale with the size of a Fahrenheit degree, and Réaumur, still found in older European recipes and engineering texts, divides the water range into 0–80.
The exact relations used here: °F = °C × 9/5 + 32; K = °C + 273.15; °R = (°C + 273.15) × 9/5; °Ré = °C × 4/5.
Absolute zero is 0 K, which is −273.15 °C, −459.67 °F, 0 °R and −218.52 °Ré. Below that line the status line shows a warning; the numbers are still displayed, but no such temperature exists.
Negative readings are normal on the everyday scales — a winter night at −10 °C is 14 °F — so the fields accept a minus sign. On Kelvin and Rankine every negative number is below absolute zero.
Results are rounded to twelve significant digits, so 100 °C shows 212 °F and 373.15 K rather than 373.15000000000003. Each value is converted once, from the scale you typed to Celsius and on to the other four.
One or two decimals are enough for weather, cooking and most engineering work; the fixed points (0 °C = 32 °F, 100 °C = 212 °F, 37 °C ≈ 98.6 °F) make it easy to check the converter against any textbook.