Temperature Converter

A temperature converter switches a value between the three scales used in daily life and science: Celsius, Fahrenheit, and Kelvin. Unlike length or weight, temperature conversion is not a simple multiplication, because the scales have different zero points as well as different degree sizes, which is exactly why doing it in your head is error-prone. This tool applies the correct formula automatically. To convert Celsius to Fahrenheit you multiply by 9/5 and add 32, so 20 C becomes 68 F; to reverse it you subtract 32 and multiply by 5/9. Kelvin shares the same degree size as Celsius but begins at absolute zero, so you simply add 273.15 to a Celsius value to get Kelvin (25 C = 298.15 K). A few reference points make conversions easy to check: water freezes at 0 C, 32 F, and 273.15 K; it boils at 100 C, 212 F, and 373.15 K; normal human body temperature is about 37 C or 98.6 F; and absolute zero is 0 K, -273.15 C, and -459.67 F. There is also a neat sanity check: -40 C and -40 F are exactly equal, the one point where the two scales cross. Temperature conversion shows up when following a recipe with an oven temperature in the other scale, reading a foreign weather forecast, doing science homework that requires Kelvin, or working in a lab. Negative values and the offset zero points are where mistakes happen most, so letting the tool apply the formula avoids them. Everything runs locally in your browser, privately and offline.