Converters How-to guides
Celsius to Fahrenheit: an easy formula, with examples
Learn the Celsius-to-Fahrenheit formula, convert Fahrenheit back to Celsius, and check common examples such as 25 °C, 180 °C and a 350 °F oven setting.
A forecast says 77 °F, or a recipe asks you to heat the oven to 350 °F. If you're used to Celsius, neither number is very helpful until you convert it. You only need one multiplication and one addition, but the order matters when going the other way.
Celsius to Fahrenheit: multiply, then add
Take 25 °C as an example. Multiply 25 by 1.8 to get 45, then add 32. The answer is 77 °F. The same steps turn 0 °C into 32 °F; zero on one scale isn't zero on the other.
For Fahrenheit to Celsius, undo those steps in reverse order. Starting with 77 °F, subtract 32 to get 45, then divide by 1.8 to get 25 °C. Keep the brackets when typing the formula into a calculator.
Fahrenheit = (Celsius × 1.8) + 32
Celsius = (Fahrenheit − 32) ÷ 1.8Sources: NIST: exact temperature conversions and temperature intervals
A few Celsius and Fahrenheit values worth knowing
These are direct conversions of temperature readings. The values in this table are exact; no rounding is needed.
| Celsius (°C) | Fahrenheit (°F) |
|---|---|
| -40 | -40 |
| 0 | 32 |
| 10 | 50 |
| 20 | 68 |
| 25 | 77 |
| 30 | 86 |
| 100 | 212 |
| 180 | 356 |
What is 350 °F in Celsius?
Subtract 32 from 350, then divide 318 by 1.8. That gives 176.666… °C, or about 176.67 °C. A recipe or oven dial may use a nearby setting such as 175 °C or 180 °C. Those are practical rounded settings, not exact equivalents.
A unit conversion also doesn't adjust a recipe for a fan oven. If the recipe gives a separate fan setting, use that instruction. Changing the temperature scale and changing the cooking method are two different decisions.
A temperature reading isn't the same as a temperature change
A rise of 10 °C is a rise of 18 °F. You don't add 32 when converting a change, because the starting-point offset cancels out. Adding 32 would give 50 °F, which is the reading equivalent to 10 °C, not the size of that change.
ToolBarKit's Temperature converter handles readings. Choose Celsius and Fahrenheit, enter the value, and copy the result with its unit. Kelvin is available too: add 273.15 to a Celsius reading to get kelvin. The tool rejects readings below absolute zero, which is 0 K or −273.15 °C.
Open the Temperature converter →
Sources: NIST: exact temperature conversions and temperature intervals
Common questions
Is doubling Celsius and adding 30 accurate?
It's a rough shortcut. For 25 °C it gives 80 °F, while the correct answer is 77 °F. Use the full formula or the converter when you need a precise value.
Why do Celsius and Fahrenheit meet at −40?
Putting −40 into the formula gives (−40 × 1.8) + 32 = −40. That's the temperature where both scales show the same number.
Sources and further reading
This guide combines the linked references with examples and the current behavior of ToolBarKit’s tools. Published by the ToolBarKit team; external guidance and tool behavior can change.