## Find the temperature conversion formula, chart, and calculator!

### F to C: Fahrenheit to Celsius Conversion Calculator

Fahrenheit | Celsius |
---|---|

°F | °C |

Enter a value for Fahrenheit or Celsius to convert to the other.

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If -40 is the same on both scales, is there a temperature above 0 where both Celsius and farenheit read the same amount?

The conversion scale between °C and °F is a straight line. So is the line y=x. Linear equations can either have:

* No solutions (parallel lines)

* One solution (they cross once and diverge from there on both sides)

* Infinite solutions (they're the same line)

We looked at comments below and found one comment interesting. When you convert Fahrenheit to Celsius (as shown above), the last thing you need to do is multiply by 5/9 or .5556. Since 5/9 is only approximately equal to .5556, you do get slightly different answers depending on whether you use 5/9 or .5556. The commenter suggests that instead of multiplying by 5/9 or .5556 that you divide by 9/5 or 1.8. This is because 9/5 is exactly equal to 1.8 and, therefore, you will avoid getting slightly different answers. The only drawback that we see in using this method is that it is not the formula you normally see in textbooks (if that’s a concern).

I have to do temperature conversions frequently and have been using the "1.8 method" for years. It is far easier than messing with fractions, especially when teaching someone else to do conversions. I can't understand why anyone still teaches the 5/9, 9/5 method.

IS THIS TRUE? How to convert Celsius to fahrenheit

This is much easier:

C->F ADD 40, Divide by 5, Multiply by 9, SUBTRACT 40

F->C ADD 40, Divide by 9, Multiply by 5, SUBTRACT 40

Notes: always ADD 40 first, if you *want Fahrenheit* then you want 'more' range so multiply by 9 (and divide by 5), if you *want Celsius* then you want 'less' range so divide by 9 (and multiply by 5), then SUBTRACT 40

No 32's in sight.

I need clear examples

I cannot change the Fahrenheit to Celsius. I use the calculator, it is (37-32) x 0.5556, right

Multiplying by 5/9? Not exactly "easy" though...

As someone who has to work with both temperature systems, I use this for a quick and easy way to get a number close enough to understand.

For C to F "double it and add 30" so 20 C = (2x20) + 30 = 70F which is close to the real value of 68F to know it's a nice day.

F to C "subtract 30 and halve it" so 100F = (100-30)/2 = 35C which is close to the actual value of 37.8C and getting pretty warm.

It's not perfect, but it is quick and easy enough to do in your head.

Another trick? Remember that:

0C is 32F

16C is 61F, and

28C is 82F.

If the number you want is close to those 3 numbers then just treat 2F = 1C and work it out from there. What is 20C? 16C + 4 = 61F + 8 = 69F which is close enough to 68F for me. What is 26F? 32-26 = 6F or 3C so it's 3C below freezing or -3C.

(Side note, -40C is the same as -40F but by then who cares, that's just seriously cold everywhere...)

Useful Information, Helps a lot.

## Comments