# roof pitch to degrees

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What is the math to get degrees from a rise/run pitch? Some of the tools don't let rise/run be used.

my method is to photocopy the page out of graphic standards, and keep it very handy. 'Expression of slope'

Math, ehh, not for me

from my cheat sheet:

1:12 - 4?46' - 8.3%

2:12 - 9?28' - 16.7%

3:12 - 14?02' - 25%

4:12 - 18?26' - 33.3%

5:12 - 22?30' - 41.4%

6:12 - 26?34' - 50%

7:12 - 30?0' - 57.5%

8:12 - 33?42' - 67%

9:12 - 36?52' - 75%

10:12 - 40?0' - 84%

12:12 - 45?0' - 100%

Spinner

4:12 =4/12= 0.333 > 1/tan(0.333) = 18.4349 = 18?26'

Gracie tante, Islandmon, and Spinner. I will keep my old adjustable triangle out, too. Good old Graphics Standards. It is in the shelf behind me while I troll the internet....

VW's will also figure these out for you. Draw a line using "Cartesian" input (eg: X=12'/ Y=4') then with the line selected change to "Polar". The OIP will show you the angle (18.43?).

That helps, but again there are some tools for adjusting the roof that need the degrees as input. If it is already drawn and you just want to change it to see how it looks, it would be helpful to be able to use either format, just as when you are building it for the first time.

Thanks!

I believe, Don, that even in the boxes that display degrees you can enter a ratio and it will update accurately. I don't work a great deal with roof faces, but rather with roof framing members. . .and that's generally how I enter things.

Good luck,

blackdogarch, which tools? I have yet to encounter an entry box for the pitch of a roof element that doesn't accept a ratio.

One of the editing tools. Maybe I just had a temporary problem since I can't replicate it, but at the time, I could not enter a ratio. Ghosts in the machine...

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