How to Convert Celsius to Fahrenheit (Formula and Quick Trick)

Whether you are reading a foreign weather forecast, following a recipe written for another country, or checking a thermometer that uses the “wrong” scale, converting between Celsius and Fahrenheit comes up more than you would expect. The formulas are short, there is a handy mental shortcut, and a few reference points cover most situations. This guide walks through all three, then points you to a free converter for the exact number.

The two formulas in plain language

Both conversions are built on the same two facts: Fahrenheit runs on a larger scale (every Celsius degree is worth 1.8 Fahrenheit degrees), and the two scales start from different zero points (32 apart).

• Celsius to Fahrenheit: multiply by 1.8, then add 32. So 20 degrees Celsius becomes 20 times 1.8, which is 36, plus 32, giving 68 degrees Fahrenheit.
• Fahrenheit to Celsius: subtract 32 first, then divide by 1.8. So 50 degrees Fahrenheit becomes 50 minus 32, which is 18, divided by 1.8, giving 10 degrees Celsius.

The order matters. Going to Fahrenheit you multiply then add; coming back you subtract then divide. Keep that sequence straight and you will never get a wildly wrong answer.

A quick mental approximation

When you only need a ballpark, skip the 1.8 and use this shortcut for Celsius to Fahrenheit: double the Celsius number, then add 30.

For 20 degrees Celsius, double to 40, add 30, and you get 70. The exact answer is 68, so you are within a couple of degrees, which is plenty for deciding what to wear. The approximation drifts a little at extreme temperatures, but for everyday weather it is close enough to be genuinely useful.

Reference points worth memorizing

A handful of anchor temperatures let you sanity-check any conversion at a glance:

• Water freezes at 0 degrees Celsius, which is 32 degrees Fahrenheit.
• A comfortable room sits around 20 to 22 degrees Celsius, roughly 68 to 72 degrees Fahrenheit.
• Normal body temperature is about 37 degrees Celsius, which is 98.6 degrees Fahrenheit.
• Water boils at 100 degrees Celsius, which is 212 degrees Fahrenheit.
• A moderate oven for baking is often around 180 degrees Celsius, close to 350 degrees Fahrenheit.

If a conversion you just did lands far from the nearest anchor, you probably mixed up the steps. These points catch most mistakes instantly.

Get the exact number

For anything where precision matters, like a recipe or a fever reading, open the Temperature Converter. Type a value in either scale and it returns the other immediately, no formula required.

The Temperature Converter is especially handy for:

• Following recipes that list oven temperatures in the other scale.
• Reading a weather forecast from a country that uses a different unit.
• Double-checking a thermometer reading without doing the math by hand.

It is free, needs no sign-up, and runs entirely in your browser, so nothing you enter is uploaded anywhere.

Related converters

Temperature is rarely the only unit that trips you up across regions. When a recipe or a set of instructions uses unfamiliar measurements, the Length Converter handles inches, centimeters, feet, and meters, while the Weight Converter sorts out grams, ounces, kilograms, and pounds. And if you need a figure written out in full words, perhaps for a document or a check, the Number to Words tool spells it out for you.

The short version

To convert Celsius to Fahrenheit, multiply by 1.8 and add 32. To go back, subtract 32 and divide by 1.8. For a fast estimate, double the Celsius value and add 30. When you need the exact figure with zero risk of a slip, the Temperature Converter gives it to you in one step.