If you’ve ever stared at a weather report from another country and wondered whether 25°C means you need a jacket or shorts, you’re not alone. Converting Celsius to Fahrenheit can feel like a math headache—but it doesn’t have to be. With one simple formula and a quick shortcut, you can do it in seconds.
The Formula
The official formula looks like this:
°F=(°C×95)+32°F = (°C × \tfrac{9}{5}) + 32
That means you multiply the Celsius temperature by 9, divide by 5, then add 32. For example:
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0°C → (0 × 9 ÷ 5) + 32 = 32°F
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25°C → (25 × 9 ÷ 5) + 32 = 77°F
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100°C → (100 × 9 ÷ 5) + 32 = 212°F
It’s accurate every time, but doing fractions in your head isn’t always practical.
The Quick Mental Shortcut
If you just want a ballpark answer, use this trick:
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Double the Celsius number.
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Add 30.
That’s it.
So 20°C becomes about 70°F (20 × 2 = 40, plus 30 = 70). The exact answer is 68°F, so you’re within 2 degrees—close enough for daily use.
Another example:
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30°C → Double to 60, add 30 = 90°F. The exact conversion is 86°F, so again, it’s close.
This shortcut works best in the middle range of temperatures (say, -10°C to 30°C). At extreme highs or lows, the gap gets wider, but for everyday weather checks, it’s a lifesaver.
When to Use Which Method
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Use the formula when accuracy matters: cooking, science, and medical readings.
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Use the shortcut when you just want to know if you need a sweater or sunscreen.
A Simple Way to Remember
Think of it like this: Celsius is based on water (freezes at 0, boils at 100), while Fahrenheit is based on “living comfort” (freezes at 32, room temp around 70). Once you know the two systems start at different points, the conversion makes more sense.
Related: 180 C to F
Final Thought
Don’t let Celsius vs. Fahrenheit confuse you. Memorise the formula if you like precision, or use the “double it and add 30” hack for quick estimates. Either way, you’ll always know what the numbers really mean.
