ConverterFahrenheit to Celsius Converter
Convert a Fahrenheit temperature reading to Celsius when a forecast, thermostat, oven setting, appliance instruction, or equipment specification is written in degrees F. The result is calculated as you type and displayed with at most two decimal places.
Enter decimals with a point, such as 20.5. Commas are rejected instead of being treated as decimal or grouping separators. Scientific notation works where the browser accepts it. Results display up to two decimals, and trailing zeroes are omitted.
Subtract Before You Scale
For a temperature reading, use Celsius = (Fahrenheit - 32) x 5/9. Subtracting 32 removes the Fahrenheit zero-point offset; multiplying the remainder by 5/9 then changes the degree size.
The order is part of the formula. Multiplying the Fahrenheit reading by 5/9 before subtracting 32 produces a different and incorrect Celsius reading.
A 72 Degree Fahrenheit Walkthrough
Start with 72 degrees F. Subtract 32 to get 40, then multiply 40 by 5/9. The mathematical result is 22.2222... degrees C, and this page displays 22.22.
Keep the original 72 degrees F beside a copied result when someone may need to verify the source reading or apply a different rounding rule.
Fahrenheit-First Reference Values
| Fahrenheit reading | Celsius display | Useful context |
|---|---|---|
| 0 F | -17.78 C | Cold-weather reference |
| 32 F | 0 C | Water-freezing reference |
| 68 F | 20 C | Indoor-temperature reference |
| 72 F | 22.22 C | Forecast or thermostat reference |
| 212 F | 100 C | Water-boiling reference at standard atmospheric pressure |
| 350 F | 176.67 C | Common Fahrenheit oven setting |
A Reading Is Not An Interval
The full formula converts a reading tied to the Fahrenheit scale. A temperature change has no zero-point offset, so an 18-degree-F increase corresponds to a 10-degree-C increase: multiply the interval by 5/9 without subtracting 32.
Label the result as a reading or a change when the distinction matters. Applying the reading formula to an interval produces the wrong answer.
Display Rounding And Source Values
The formula is evaluated before display formatting. This tool shows at most two decimal places and removes trailing zeroes, so 68 degrees F is shown as 20 degrees C while 72 degrees F is shown as 22.22 degrees C.
The displayed result is a formatted JavaScript Number value, not a promise of unlimited decimal precision. Preserve the source reading and use the precision required by the document, device, or procedure that receives the value.
Ordinary Absolute-Zero Boundary
The ordinary thermodynamic absolute-zero boundary is approximately -459.67 degrees F, corresponding to -273.15 degrees C. The boundary value converts normally.
For an input below -459.67 degrees F, the tool still shows the mathematical result and adds a warning. That output should not be interpreted as an ordinary physical temperature.
Frequently Asked Questions
Subtracting 32 removes the Fahrenheit scale offset. The remaining value can then be rescaled by 5/9 to produce the corresponding Celsius reading.
72 degrees F converts to 22.22 degrees C under this page's two-decimal display policy.
No. For a temperature interval, multiply the Fahrenheit change by 5/9 without subtracting 32. For example, an 18-degree-F increase equals a 10-degree-C increase.
The tool shows the mathematical Celsius result and a warning. A value below the ordinary thermodynamic absolute-zero boundary should not be interpreted as an ordinary physical temperature.
Learn More About This Topic
Use the supporting references when the assumptions behind Fahrenheit to Celsius matter as much as the immediate result. For more context, read celsius vs fahrenheit: readings, intervals, and scale differences before using the result in a real workflow.
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