Celsius to Fahrenheit Calculator — °C to °F Converter
Enter a temperature in Celsius to instantly get the Fahrenheit equivalent using the exact formula °F = °C × 9/5 + 32, plus Kelvin and a linear conversion chart.
°C
°F = °C × 9/5 + 32
- 1
°C × 9÷5 (scale)
25 × (9÷5) = 45 - 2
°F = scaled + 32
45 + 32 = 77
How does this calculator work?
Multiply the Celsius value by 9/5 (or 1.8) and add 32 to get Fahrenheit. The formula is linear: the graph is a straight line crossing at −40 °C = −40 °F. Key landmarks: 0 °C = 32 °F, 20 °C = 68 °F, 37 °C = 98.6 °F, 100 °C = 212 °F. No approximation — the formula is exact by definition.
Formula
How this is calculated
The Celsius and Fahrenheit scales have different zero points and different degree sizes, which is why conversion requires both a multiplicative scale factor and an additive offset. One Celsius degree spans 9/5 (1.8) Fahrenheit degrees — because water's boiling-to-freezing range is 100 °C but 180 °F — so you first multiply by 9/5. Then you add 32 to account for the 32 °F gap between the two scales' freezing points.
The result is a linear function, meaning the conversion graph is a straight line. That line crosses through the single coincidence point −40 °C = −40 °F, where both scales read the same value. Every other temperature has a unique pair of readings.
Kelvin is included for completeness: it is simply Celsius shifted up by 273.15, placing zero at absolute zero (the lowest theoretically possible temperature) rather than at the freezing point of water. No degree symbol is used for Kelvin because it is an SI base unit, not a degree-based scale.
Frequently asked questions
A common shortcut: double the Celsius temperature and add 30. For example, 20 °C → 40 + 30 = 70 °F (exact is 68 °F). For greater accuracy, multiply by 1.8 and add 32, or use the exact 9/5 form.
37 °C = 37 × 9/5 + 32 = 66.6 + 32 = 98.6 °F, which is the standard human body temperature.
Yes — exactly −40 degrees. At this point both scales agree: −40 °C = −40 °F. For any temperature above −40 the Fahrenheit reading is always higher than the Celsius one.
Also known as
TG we-Calculate Editorial Team. (2026). Celsius to Fahrenheit Calculator — °C to °F Converter [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/celsius-to-fahrenheit-calculator
TG we-Calculate Editorial Team. "Celsius to Fahrenheit Calculator — °C to °F Converter." TG we-Calculate. 2026. https://we-calculate.com/calculator/celsius-to-fahrenheit-calculator.
TG we-Calculate Editorial Team, "Celsius to Fahrenheit Calculator — °C to °F Converter," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/celsius-to-fahrenheit-calculator
@misc{wecalculate_celsius_to_fahrenheit_calculator, title = {Celsius to Fahrenheit Calculator — °C to °F Converter}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/celsius-to-fahrenheit-calculator}}, year = {2026}, note = {TG we-Calculate} }
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