The formula for converting fahrenheit to celsius

Here is how to convert Fahrenheit to Celsius temperatures, including the formula for the temperature conversion and worked example problems. Fahrenheit is a temperature scale in the United States and some other countries, while Celsius is a metric scale used elsewhere in the world.

• °C = (°F – 32) x 5/9 or °C = (°F – 32) ÷ 1.8
• Take the Fahrenheit temperature, subtract 32, multiply by 5, and divide by 9.
• Take the Fahrenheit temperature, subtract 32, and divide by 1.8

Fahrenheit to Celsius Formula

The Fahrenheit to Celsius conversion formula is:

°C = (°F – 32) x 5/9

So, to convert from Fahrenheit to Celsius, subtract 32 and multiply by 5/9 or approximately 0.5556.

If you don’t like working with fractions, here’s an equivalent formula:

°C = (°F – 32) ÷ 1.8

It does not matter which formula you use. You’ll get the same answer!

Need more practice? Follow an example converting the body temperature of cat from Fahrenheit to Celsius.

Fahrenheit to Celsius Examples

These two example problems show the temperature conversion using both formulas:

For example, convert body temperature of 98.6 °F to °C.

°C = (°F – 32) ÷ 1.8
°C = (98.6 – 32) ÷ 1.8 = 66.6 / 1.8 = 37

For example, 350 °F is a normal baking temperature. What temperature do you set an oven in Celsius?

°C = (°F – 32) x 5/9
°C = (350 – 32) x 5/9 = 318 x 5 ÷ 9 = 1590 ÷ 9 =176.6 or about 177

Quick Fahrenheit to Celsius Approximation

Sometimes you don’t need an exact temperature conversion. Here’s an easy way of approximating the Fahrenheit to Celsius conversion:

1. Subtract 30 from the Fahrenheit temperature.
2. Divide this number by 2.

For example, a temperature of 74 °F is around:

(74 -30)/2 = 44/2 = 22 °C

The exact temperature is 23.3 °C , so the approximation is fairly close.

The approximation from Celsius to Fahrenheit is also simple.

1. Multiply the Celsius temperature by 2.
2. Add 30 to this value.

For example, a temperature of 22 °C is about:

(22 x 2) + 30 = 44 + 30 = 74 °C

Fahrenheit to Celsius Conversion Table

Here’s a handy table so you can look up the Fahrenheit to Celsius conversion rather than calculate it. Notice Fahrenheit and Celsius are the same at -40 °.

Why Use the Fahrenheit Scale?

The Fahrenheit scale takes its name from German scientist Daniel Fahrenheit, who gets credit for the invention of the mercury thermometer in 1714. The modern Fahrenheit scale divides the interval between the freezing and boiling points of water into 180 degrees. This puts the freezing point of water at 32 °F, the boiling point of water at 212 °F, and normal body temperature close to 100 °F (really 98.6 °F).

The main reason for using the Fahrenheit scale is because it’s in use in the United States and its territories, as well as the Bahamas, Belize, and the Cayman Islands. While the Celsius scale is the typical scale in the metric system, the Fahrenheit scale is more precise (without adding a decimal point). For example, a room at 72 °F is 22.22 °C. If you set the thermostat for 22 °C, it’s 71.6 °C.

References

• Balmer, Robert T. (2010). Modern Engineering Thermodynamics. Academic Press. ISBN 978-0-12-374996-3.
• Boyes, Walt (2009). Instrumentation Reference Book. Butterworth-Heinemann. ISBN 978-0-7506-8308-1.
• Greenslade, Roy (December 29, 2014). “Newspapers run hot and cold over Celsius and Fahrenheit“. The Guardian.
• Preston–Thomas, H. (1990). “The International Temperature Scale of 1990 (ITS-90)”. Metrologia. 27 (1): 6. doi:10.1088/0026-1394/27/1/002