Contents
How the converter works
To convert Celsius to Fahrenheit, multiply the Celsius value by 1.8 and add 32. The converter begins with 20 °C = 68 °F, accepts negative and decimal values, and lets either number field drive the calculation.
The conversion changes both the interval and the zero point
The factor 1.8, which is the same as 9/5, adjusts the size of a degree interval. Adding 32 then aligns the scale with Fahrenheit. For the reverse direction, use .
The equations are exact definitions, not approximations. The US National Institute of Standards and Technology publishes both conversion formulas and the principal scale reference points.
Weather, baking, and the temperature where the scales meet
20 °C becomes 68 °F. Multiply 20 by 1.8 to get 36, then add 32. This is a useful checkpoint when reading an indoor thermostat.
180 °C becomes 356 °F. A recipe written for a Celsius oven often needs this conversion: 180 × 1.8 + 32 = 356. An oven dial may offer only 350 °F, so the appliance setting can still require practical rounding.
-40 °C becomes -40 °F. This is the one point where both scales show the same number. It is also a quick way to catch a missing sign in a calculation.
Enter a value on the side you already know
The left field starts in Celsius and the right field in Fahrenheit. Change either value and the other side updates immediately. The middle button swaps both scales and values, while each selector can independently switch to Kelvin or Réaumur.
Decimal commas are accepted as well as decimal points. Displayed answers are rounded to at most two decimal places and trailing zeroes are removed.
A temperature reading and a temperature change follow different rules
The +32 offset belongs to an actual temperature reading. It does not belong to a temperature difference. An increase of 5 °C corresponds to an increase of 9 °F, wherever the interval begins.
Water freezing at 32 °F and boiling at 212 °F are standard reference points. The actual boiling temperature changes with pressure, so the formula converts the number but does not predict what water will do at a particular altitude.
The converter also performs arithmetic below absolute zero. Values lower than -273.15 °C or -459.67 °F are not physically possible temperatures, even if the mathematical conversion is valid.
Celsius to Fahrenheit questions
These short answers cover the details most likely to cause an incorrect result.
What is the quickest exact formula?
Multiply Celsius by 9/5 and add 32: °F = °C × 9/5 + 32.
What is 37 °C in Fahrenheit?
37 °C equals 98.6 °F.
Can I estimate Fahrenheit mentally?
Doubling Celsius and adding 30 gives a convenient rough estimate near everyday weather temperatures. Use the exact formula when accuracy matters.
Why is 1 °C not equal to 1 °F?
The scales divide the same freezing-to-boiling interval into different numbers of degrees. A Celsius interval is 1.8 times a Fahrenheit interval.
Does the calculator round the input?
No. It calculates from the entered value and rounds only the displayed result to at most two decimal places.
Similar calculators
You may find the following calculators on the same topic useful:
- Réaumur to Celsius Converter. Convert whole, negative, or decimal Réaumur values to Celsius and reverse the calculation from either field.
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