How to use the Fahrenheit to Celsius converter
Choose the direction of conversion, then enter the temperature. The result updates immediately in the other scale. Use Fahrenheit to Celsius for an °F value you want expressed in °C, or switch the direction when you already have a Celsius temperature.
The conversion relationship is exact. The displayed number may be rounded for readability because many Fahrenheit values convert to repeating decimals in Celsius and vice versa.
Fahrenheit to Celsius and Celsius to Fahrenheit formulas
The Fahrenheit and Celsius scales have different zero points and different degree sizes. Subtracting 32 handles the offset when converting from Fahrenheit, while the factor of 1.8 accounts for the difference in the size of each degree interval.
NIST publishes the exact Fahrenheit-to-Celsius relationship in its Metric Conversion Card and notes that an interval of one Celsius degree corresponds to 1.8 Fahrenheit degrees in its SI temperature guidance.
Common Fahrenheit and Celsius temperatures
32°F = 0°C
The freezing point of water is commonly used as a reference point for the two scales.
68°F = 20°C
A useful indoor-temperature reference.
77°F = 25°C
A common warm-room or mild-weather reference.
86°F = 30°C
A useful hot-weather reference when translating forecasts.
98.6°F ≈ 37°C
A commonly cited body-temperature reference; individual body temperature varies.
212°F = 100°C
A common water-boiling reference at standard atmospheric pressure.
Why you cannot simply halve a Fahrenheit temperature
A shortcut such as “divide Fahrenheit by two” can sometimes produce a rough weather estimate, but it is not the conversion formula. The Fahrenheit scale is offset from Celsius by 32 degrees at the freezing point of water, and the size of the degree interval is also different.
For example, 68°F is exactly 20°C. Dividing 68 by two would give 34, which is not close enough for a true temperature conversion. The converter applies both the offset and the scale factor.
Temperature conversion examples
Weather
86°F converts to 30°C, while 50°F converts to 10°C. These are useful reference values when reading forecasts from countries that use a different scale.
Cooking
350°F converts to about 176.67°C mathematically. Oven settings are commonly rounded to practical increments, and real ovens can cycle around the set temperature.
Cold temperatures
-4°F converts to -20°C. At -40°, the two scales meet: -40°F equals -40°C.
Rounding and measurement precision
A conversion can be mathematically exact while the original measurement is not. If a weather app reports 72°F to the nearest whole degree, displaying a converted result with six decimal places would imply more measurement precision than the source provides.
Use the extra decimal places when the underlying measurement supports them, such as a laboratory or technical reading. For everyday weather, room temperature, or cooking, a rounded result is usually easier to use.
Related calculator
For ratios, percent change, and other everyday arithmetic, use the Percentage Calculator.
Example: Rowan reads a US weather forecast
Rowan sees a forecast of 77°F. Subtracting 32 gives 45; multiplying 45 by 5/9 gives 25°C. This is a temperature reading, so the 32-degree offset must be included.
For a change of 18°F, the corresponding temperature change is 10°C. Converting a temperature difference uses the scale factor only, without subtracting 32.
Exact conversion does not mean the original measurement was exact
The Fahrenheit-to-Celsius relationship is defined exactly, but a temperature reading can still be approximate. A weather report rounded to the nearest degree does not become more precise just because the converted result can be displayed with many decimal places.
Match the displayed precision to the purpose: whole or one-decimal temperatures are usually enough for everyday weather, while technical measurements may justify more digits.
Useful Fahrenheit-to-Celsius reference points
32 F
0 C - the familiar freezing-point reference for water.
68 F
20 C - a useful indoor-temperature reference.
86 F
30 C - a useful hot-weather reference.
212 F
100 C - the boiling-point reference for water at standard atmospheric pressure.
Fahrenheit to Celsius converter FAQs
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit temperature, then divide by 1.8. The equivalent exact formula is C = (F − 32) × 5/9.
How do I convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 1.8, then add 32. The equivalent exact formula is F = C × 9/5 + 32.
What is 32°F in Celsius?
32°F equals 0°C exactly.
What temperature is the same in Fahrenheit and Celsius?
The two scales have the same numeric value at -40 degrees, so -40°F equals -40°C.
What is 98.6°F in Celsius?
98.6°F converts to approximately 37°C.
What is 100°C in Fahrenheit?
100°C equals 212°F. Water boils at about this temperature at standard atmospheric pressure, although boiling temperature changes with pressure and altitude.
How many decimal places should I keep in a temperature conversion?
Keep enough decimal places for the precision of the original measurement. Adding many decimal places to a rough temperature does not make the underlying measurement more precise.
The Fahrenheit/Celsius conversion relationship is exact. Displayed results are rounded for readability; the appropriate number of significant digits depends on the precision of the original temperature.