Converters
Temperature Converter
Convert Celsius, Fahrenheit, and Kelvin.
Result
Enter your numbers and press Calculate to see the result.
Calculating…
How temperature conversion works
Temperature scales differ in both step size and zero point, so converting between them uses formulas rather than simple factors. The converter routes every conversion through Celsius and supports Fahrenheit, Kelvin, and Rankine.
Formulas
°F = °C × 9/5 + 32
°C = (°F − 32) × 5/9
K = °C + 273.15
°R = (°C + 273.15) × 9/5
Reference points
| Point | °C | °F | K |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 20 | 68 | 293.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Water boils | 100 | 212 | 373.15 |
Worked example
Converting 20 °C to Fahrenheit: 20 × 9/5 + 32 = 36 + 32 = 68 °F — a mild spring day. The same 20 °C is 293.15 K.
Which scale is used where
Celsius is the everyday scale in most of the world and in science; Fahrenheit stays in common use in the United States for weather, cooking, and body temperature; Kelvin is the SI unit for scientific work because it starts at absolute zero and has no negative values; and Rankine is Kelvin's Fahrenheit-sized counterpart, still seen in some US engineering fields.
Handy landmarks to memorize
A few anchor points make quick estimates easy without a formula. −40° is the one temperature where Celsius and Fahrenheit meet. 16°C ≈ 61°F is a cool room, 28°C ≈ 82°F is a hot day, and 180°C ≈ 350°F is a common baking temperature. For a rough mental conversion from Celsius to Fahrenheit, double the number and add 30 — close enough for weather, though the calculator gives the exact value.
For lengths, weights, areas, and volumes, use the unit converter.
Temperature Converter — frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32: °F = °C × 1.8 + 32. So 20 °C is 20 × 1.8 + 32 = 68 °F.
How do I convert Fahrenheit to Celsius?
Subtract 32 and multiply by 5/9: °C = (°F − 32) × 5/9. So 98.6 °F is (98.6 − 32) × 5/9 = 37 °C.
What is Kelvin and where is absolute zero?
Kelvin is the scientific scale that starts at absolute zero, the coldest possible temperature. 0 K equals −273.15 °C, and K = °C + 273.15, so water freezes at 273.15 K.
What is the Rankine scale?
Rankine is the absolute counterpart of Fahrenheit, used mainly in some US engineering fields: 0 °R is absolute zero and °R = (°C + 273.15) × 9/5.