Temperature Converter
Convert between Celsius (°C), Fahrenheit (°F) and Kelvin (K). All formulas are exact — no rounding applied to the conversion itself.
Formula & conversion factors
°F to °C: °C = (°F − 32) × 5/9
°C to K: K = °C + 273.15
K to °C: °C = K − 273.15
Note: unlike most unit conversions, temperature involves an offset, not just a scaling factor. This is why you cannot simply multiply by a single number — the 32° shift (Fahrenheit) and 273.15 shift (Kelvin) must be applied correctly.
1Worked example: body temperature is 37 °C. 37 × 9/5 + 32 = 66.6 + 32 = 98.6 °F (the classic clinical thermometer reading, confirming the formula is correct).
Common questions
How do you convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 (or 1.8), then add 32. For example, 20 °C × 1.8 + 32 = 68 °F.
What is absolute zero?
Absolute zero is 0 K = −273.15 °C = −459.67 °F. It is the lowest possible temperature — the point at which all thermal motion ceases. It cannot be reached in practice.
Why does this converter use Kelvin as the base unit internally?
Kelvin is the SI base unit of temperature and has no negative values in normal use, making it the most natural reference point for conversion math. This is also the base unit used in RTD and thermocouple calculations (see our upcoming Engineering tools).
At what temperature are Celsius and Fahrenheit equal?
−40. At −40 °C = −40 °F exactly. This is the only point where the two scales intersect.