What's an Easy Way to Convert Celsius to Fahrenheit?

thermometer against bright blue sky — A hot day means something very different number-wise in Fahrenheit and Celsius. mikroman6/Getty Images

Ever found yourself chatting with an international friend and get tripped up when they mention today's temperature? For many of us, the need to convert Celsius to Fahrenheit (or vice versa) pops up more often than we expect.

With a few handy conversion tips, you won't have to sweat (or shiver) the next time you're figuring out temperature units across borders.

Contents

Two Temperature Scales
Approximate Conversions: Fahrenheit to Celsius and Vice Versa
Exact Calculations for Celsius and Fahrenheit
Cool Facts to Drop at Your Next Gathering

Two Temperature Scales

Fahrenheit

Daniel Gabriel Fahrenheit concocted the Fahrenheit scale for measuring temperature in the year 1724, and he didn't stop there. He also invented mercury thermometers!

Celsius

The Celsius scale wasn’t far behind, arriving in 1742 thanks to Anders Celsius. But, there's a twist. When first introduced, Mr. Celsius flipped the script. He had labeled 0 as the boiling point of water and 100 as its freezing point.

However, after his demise, Carl Linnaeus decided things needed to be more intuitive. He inverted the scale to the version we know today: 0 for freezing and 100 for boiling.

Approximate Conversions: Fahrenheit to Celsius and Vice Versa

Let’s dive into the art of temperature conversion. Sometimes, you just need a quick approximation. We've got you!

Celsius to Fahrenheit

To get a rough Fahrenheit temperature, double your Celsius degrees and add 30: (Celsius temp. x 2) + 30 = Fahrenheit temp. For instance, 30°C would be roughly: (30 x 2) + 30 = 90°F

Fahrenheit to Celsius

Reversing the process, subtract 30 from your Fahrenheit reading and then halve it: (Fahrenheit temp. – 30) ÷ 2 = Celsius temp. Using 80°F as a sample: (80 – 30) ÷ 2 = 25°C

Exact Calculations for Celsius and Fahrenheit

Celsius to Fahrenheit

For a more accurate Fahrenheit conversion, multiply your Celsius degree by 1.8 and then add 32: (Celsius temp. × 1.8) + 32 = Fahrenheit temp. Using 30°C: (30 x 1.8) + 32 = 86°F

Fahrenheit to Celsius

To get your Celsius temperature bang on, subtract 32 from Fahrenheit and then divide by 1.8: (Fahrenheit temp. – 32) ÷ 1.8 = Celsius temp. For 80°F, you get: (80 – 32) ÷ 1.8 = 26.6°C (or rounded to 27°C)

Cool Facts to Drop at Your Next Gathering

Just a few countries, such as the U.S., Palau, the Marshall Islands, Micronesia, the Bahamas, the Cayman Islands and Liberia, still use the Fahrenheit scale. Most countries have embraced the Celsius temperature scale.
Ever wondered why minus 40°C is the same as minus 40°F? It's where the two scales meet. Consider it a frosty high-five!
While we're on interesting temperatures, normal body temperature is typically considered to be around 98.6°F or 37°C. But remember, individual variations apply!
And if you're into chilling facts, absolute zero is minus 273.15°C or minus 459.67°F. It's the coldest temperature theoretically possible.

So, the next time you're traveling, or just indulging in some international weather chat, you'll be well-equipped to jump between degrees Celsius and degrees Fahrenheit like a pro!

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.

Frequently Answered Questions

Why is minus 40 degrees Celsius the same as minus 40 degrees Fahrenheit?

Fahrenheit and Celsius have two different scales. Each temperature scale has different intercepts and slopes so if they are plotted on the same graph they must intersect at some point.