What is the Celsius–Fahrenheit Equation Solver?
This calculator converts a temperature between the Celsius (°C) and Fahrenheit (°F) scales using the exact linear relationship that links the two. Pick the direction, type a value, and the tool applies the correct equation and shows the converted temperature. It works for any value — below freezing, room temperature, body temperature, or oven heat — and is universal (no country-specific rules apply).
How to use it
Select whether you are converting Celsius to Fahrenheit or Fahrenheit to Celsius. Enter the known temperature (decimals and negatives are allowed) and read the result. The summary table repeats your input alongside the converted value so you can copy either figure.
The formula explained
The two scales are related linearly. Going from Celsius to Fahrenheit you multiply by 9/5 (the ratio of the degree sizes) and add 32 (the freezing-point offset): $$\degree F = \frac{9}{5} \times \text{Temperature (}\degree C) + 32$$ Reversing it isolates C: $$\degree C = \frac{5}{9} \times \left( \text{Temperature (}\degree F) - 32 \right)$$ The two equations are exact inverses of each other, so converting back and forth returns the original number. The scales cross at \(-40\), where \(-40\) °C equals \(-40\) °F.
Worked example
Convert 100 °C to Fahrenheit: $$\degree F = \frac{9}{5} \times 100 + 32 = 180 + 32 = \mathbf{212 \degree F}$$ — the boiling point of water. To reverse it, $$\degree C = \frac{5}{9} \times (212 - 32) = \frac{5}{9} \times 180 = \mathbf{100 \degree C}$$
FAQ
What is normal body temperature? About 37 °C, which converts to 98.6 °F.
At what temperature are both scales equal? At \(-40\)°, where \(-40\) °C \(= -40\) °F.
Does this round results? Display values are shown to two decimals, but the underlying conversion uses full precision.
