Temperature Converter
Convert between Fahrenheit, Celsius, and Kelvin instantly.
What is Temperature Converter?
The temperature converter handles the three scales you are likely to meet: Fahrenheit (everyday U.S. use), Celsius (most of the world), and Kelvin (science and engineering).
Formula
- °C → °F: F = C × 9/5 + 32
- °F → °C: C = (F − 32) × 5/9
- °C → K: K = C + 273.15
- K → °C: C = K − 273.15
The two scales agree at −40: −40°F = −40°C.
Worked example
98.6°F (human body temperature):
- C = (98.6 − 32) × 5/9 = 37.0°C
- K = 37.0 + 273.15 = 310.15 K
How to use this calculator
- Type a temperature.
- Pick its scale.
- The other two scales appear instantly.
Frequently asked questions
Why does the calculator reject values below −273.15°C?
That is absolute zero — the coldest theoretically possible temperature (0 K). Lower values are physically meaningless.
What is 0°F supposed to represent?
Daniel Fahrenheit (1724) set 0°F at the freezing point of a specific brine solution — the coldest temperature he could reliably reproduce. He set 96°F at human body temperature; later calibration refined it to about 98.6°F.
Why do scientists use Kelvin?
Kelvin starts at absolute zero and uses the same degree size as Celsius. This makes it an "absolute" scale — ratios of Kelvin values are physically meaningful (20 K is twice as hot as 10 K in terms of particle energy), unlike ratios of °C or °F.
Is there such a thing as "degree Kelvin"?
No. It was renamed to just "kelvin" (no degree) in 1967 — so the unit is "kelvin" and the symbol is K (not °K).