Conversion of Temperature

°F to °C	Deduct 32, then multiply by 5, then divide by 9
°C to °F	Multiply by 9, then divide by 5, then add 32

Or read on to understand why ...

Explanation

There are two main temperature scales:

°F, the Fahrenheit Scale (used in the US), and

°C, the Celsius Scale (part of the Metric System, used in most other countries)

They both measure the same thing (temperature!), just using different numbers.

If you freeze water, it measures 0° in Celsius, but 32° in Fahrenheit
If you boil water, it measures 100° in Celsius, but 212° in Fahrenheit
The difference between freezing and boiling is 100° in Celsius, but 180° in Fahrenheit.

Freezing	... to ...	Boiling

Looking at the diagram, notice:

The scales start at a different number (32 vs 0), so we will need to add or subtract 32
The scales rise at a different rate (180 vs 100), so we will also need to multiply

And this is how it works out:

To convert from Celsius to Fahrenheit, first multiply by 180/100, then add 32

To convert from Fahrenheit to Celsius, first subtract 32, then multiply by 100/180

Note: 180/100 can be simplified to 9/5, and likewise 100/180=5/9.

So, this is the easiest way:

Celsius to Fahrenheit	(°C × ⁹/₅) + 32 = °F
Fahrenheit to Celsius	(°F - 32) x ⁵/₉ = °C

Convert 26° Celsius (A nice warm day!) to Fahrenheit

First: 26° × 9/5 = 234/5 = 46.8
Then: 46.8 + 32 = 78.8° F

Convert 98.6° Fahrenheit (Normal Body Temperature!) to Celsius

First: 98.6° - 32 = 66.6
Then: 66.6× 5/9 = 333/9 = 37° C

°C	°F	Description
100	212	Water boils
40	104	Hot Bath
37	98.6	Body temperature
30	86	Beach weather
21	70	Room temperature
10	50	Cool Day
0	32	Freezing point of water
-18	0	Very Cold Day
-40	-40	Extremely Cold Day (and the same number!)
(bold are exact)

Just type in a value and click in the other box