How to Convert Fahrenheit to Celsius



Two systems for measuring temperature are-Fahrenheit and Celsius. Fahrenheit is used in the Imperial system and Celsius(used to be known as Centigrade) is used in the Metric system. The United States, Jamaica and Belize still use Fahrenheit for non-scientific purposes while the rest of the world uses Celsius as a measurement for temperature. If your like me you probably use the close enough method of conversion, but what if you need to be a little more exact in your calculations? Here’s a simple formula to convert Fahrenheit to Celsius.

To convert Fahrenheit to Celsius subtract 32 from the temperature and then multiply by 5/9 (doesn’t that sound like fun).

EXAMPLE: 68F – 32 = 36

36 x 5/9 = 180/9

180/9 = 20C

To convert Celsius to Fahrenheit simply reverse the process and multiply the temperature by 9/5 and then add 32.

EXAMPLE: 0C x 9/5 = 0/5

0/5 = 0

0 + 32 = 32F

Wasn’t that easy? Well if you thought that was a little too much math here is a simple rule of thumb that might be a little easier to remember. If the Fahrenheit temperature is between 0F and 100 and you want to know the approximate temperature in Celsius, subtract 30 from the Fahrenheit temperature and then divide by 2.

EXAMPLE: 70F – 30 = 40

40/2 = 20C

In reality 70F is a little over 21C.

Let’s face it, how often are you going to need to convert ANY measurement? Well, you might need it in your line of work or if you’re making a wonderful new recipe you just found. I’ve been around for awhile…since long before Canada went metric and I remember the mass confusion,and the complaining, and the mistakes, and the… get my point.

For most daily situations the following “rules” should be enough to get you through.

Some more Rules of Thumb:

The “10% and up” Rule:

1 meter is 10% longer than 1 yard

1 liter is 10% less than 1 quart

1 kilogram is 10% more than 2 pounds

1 tonne is 10% more than 1 short ton(2,000lbs)

1 square meter is 20% greater than 1 square yard

1 cubic meter is 30% greater than 1 cubic yard

The “30” Rule:

1 foot is slightly more than 30 centimeters

1 ounce is just under 30 grams

1 fluid ounce is almost 30 millimeters

The “About” Rule

1 inch is about 25 millimeters or 2.5 centimeters

4 inches are about 10 centimeters

A 2″ X 4″ piece of lumber is about 5cm X 10cm

3 feet are about 1 meter

10 yards are about 9 meters

100 yards is about 90 meters

1 mile is about 1.5 kilometers

1 pound is about 0.5 kilograms

1 gallon is about 4.5 liters

1 US gallon is about 4 liters

1 quart is about 1 liter

1 pint is about 0.5 liters