Use the form above, enter the required values, and press Calculate. The result will appear clearly in the result box. Review the formula and example below for better understanding.
Temperature Converter
Convert Celsius, Fahrenheit, and Kelvin.
Celsius
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Fahrenheit
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Kelvin
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Rankine
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State of water
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Kelvin and Rankine are absolute scales starting at absolute zero (−273.15°C). Values below that are not physical.
Four scales, one temperature
Celsius and Fahrenheit are everyday scales with different zero points and degree sizes. Kelvin and Rankine are absolute scales used in science and engineering, beginning at absolute zero.
°F = °C × 9/5 + 32 · K = °C + 273.15 · °R = °F + 459.67
The calculator converts whatever you enter to Celsius first, then out to the others. That keeps a single, reliable path between any pair of scales.
Worked example
Water boils at 100°C, which is 212°F, 373.15 K and 671.67°R. It freezes at 0°C — that is 32°F and 273.15 K.
Reference points worth knowing
A few anchors make conversions sanity-check themselves: water freezes at 0°C / 32°F and boils at 100°C / 212°F, body temperature is about 37°C / 98.6°F, and a comfortable room sits near 20°C / 68°F.
Quick tips
- −40 is the crossover. The only reading identical in °C and °F.
- Kelvin has no minus. It starts at absolute zero, so values are never negative.
- Rough head-math. Double the °C and add 30 for a quick, approximate °F.
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. So 20°C becomes 20 × 1.8 + 32 = 68°F. To go back, subtract 32 then multiply by 5/9.
What is Kelvin?
The scientific scale that starts at absolute zero, the coldest possible temperature. It uses the same degree size as Celsius, so K = °C + 273.15.
Is there a temperature that reads the same in C and F?
Yes — minus 40. −40°C equals −40°F, the single point where the two scales cross.
What is Rankine?
An absolute scale like Kelvin but using Fahrenheit-sized degrees, mainly seen in some engineering fields. °R = °F + 459.67.