Celsius to Fahrenheit Converter
Convert °C to °F instantly — type in either box and the answer appears as you type.
40°C = 104°F
The formula
°F = °C × 9/5 + 32
Example: 40°C converts to 104°F — 40 × 9/5 = 72, 72 + 32 = 104°F.
Celsius to Fahrenheit conversion table
The two anchor points that unlock everything
Water freezes at 0°C / 32°F and boils at 100°C / 212°F — everything else is interpolation. Once those two points are locked in, the rest of the scale falls into place: 20°C (68°F) is mild, 30°C (86°F) is hot, 40°C (104°F) is dangerous. The 'double it and add 30' shortcut estimates °F from °C for weather-range temperatures and stays within a couple of degrees from about 5°C to 25°C.
Where the two scales agree is at −40: the one temperature where °C and °F read the same number. It is a genuine crossover point, not a rounding trick — and it is memorably the temperature at which frostbite warnings in both Canada and the northern US start sounding identical.
Ovens, thermostats, and bodies
American ovens dial in Fahrenheit; most of the world's ovens dial in Celsius, and recipes rarely convert themselves. The big anchors: 350°F ≈ 175°C (the default baking temperature), 400°F ≈ 200°C (roasting), 450°F ≈ 230°C (pizza and bread). A 25°F step is roughly a 15°C step, which is how most recipe adjustments translate.
Body temperature is its own world: 37°C is 98.6°F, the figure every American knows, and fever territory starts at 38°C / 100.4°F. Thermostats split the difference in cultural habits — 72°F (22.2°C) is the American comfort default, while 20-21°C is the common European setting, a gap that surprises exchange students on both sides.
Common Celsius to Fahrenheit values
Weather & comfort
Cooking temperatures
How do you convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 9/5 and add 32: °F = °C × 9/5 + 32. For example, 40°C × 9/5 + 32 = 104°F.
What is the fastest way to estimate Celsius to Fahrenheit?
Double the Celsius number and add 30. For 20°C that gives roughly 70°F (the exact answer is 68°F) — handy for weather temperatures.
What is normal body temperature, 37°C, in Fahrenheit?
37°C equals 98.6°F — the classic value for normal human body temperature.
Why does the United States use Fahrenheit?
Fahrenheit was adopted in the 18th century when it was the standard scale in English-speaking countries. Most of the world switched to Celsius in the 1960s–70s, but the US kept Fahrenheit for everyday weather, cooking, and body temperature.