# hot or cold

**URL:** <https://boards.straightdope.com/t/hot-or-cold/51459>\
**Category:** Factual Questions\
**Created:** [January 23, 2001, 9:00pm UTC](https://boards.straightdope.com/t/hot-or-cold/51459 "2001-01-23T21:00:51Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Jenin](https://avatars.discourse-cdn.com/v4/letter/j/e95f7d/32.png) [@Jenin](https://boards.straightdope.com/u/Jenin)\
**Post date:** [January 23, 2001, 9:00pm UTC](https://boards.straightdope.com/t/hot-or-cold/51459/1 "2001-01-23T21:00:51Z")

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This is actually a question my sister had, which I am hoping someone can answer…According to the Centigrade Fahrenheit conversion equation, 40 degrees Centigrade is equal to 40 degrees Fahrenheit. How can this be true? 40 degrees Centigrade is very hot while 40 degrees Fahrenheit is cold. Does the conversion equation not work for certain numbers? and if so what is the correct conversion.

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**Author:** ![Arjuna34](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@Arjuna34](https://boards.straightdope.com/u/Arjuna34)\
**Post date:** [January 23, 2001, 9:07pm UTC](https://boards.straightdope.com/t/hot-or-cold/51459/2 "2001-01-23T21:07:15Z")

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Actually, it’s -40 Celsius = -40 Fahrenheit, both of which are very cold 🙂

You can think of each temperature scale as a straight line, but with different slopes. The lines cross at one point, -40.

Arjuna34

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**Author:** ![screech-owl](https://avatars.discourse-cdn.com/v4/letter/s/82dd89/32.png) [@screech-owl](https://boards.straightdope.com/u/screech-owl)\
**Post date:** [January 23, 2001, 9:09pm UTC](https://boards.straightdope.com/t/hot-or-cold/51459/3 "2001-01-23T21:09:25Z")

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**-** 40C = **-** 40F  
(as in below 0)

And welcome to the boards!