There are several reasons why you may need to work out the pitch (angle) of your roof.  For example if you’re planning an extension, purchasing a sky light, or replacing tiles.

When calculating your roof pitch, you are trying to find out how much the roof rises over one foot.  To do this, you will need to access the roof, so read this article on how to do this safely before you begin.  

There are several ways you can measure your roof pitch, here are the most common;


With a level and a tape measure

Every good DIYer will have a spirit level and a tape measure in their toolbox.  With these two basic tools you can measure the pitch of your roof.  

  1.  Mark out the one foot point on your level (it may have markings already, if so just find it).
  2. Hold your spirit level horizontally so one end sits on the roof and the other in your hand.  
  3. Find the level point, and then with your tape measure, measure the angle from the end you’re holding down to the roof (vertically) in inches.  


If the measurement is 6 inches, your roof rises 6 inches per foot (12 inches).  So the pitch is 6/12.  From here you can use an online pitch calculator to find the measurement in degrees.  This one is 26.57 degrees.


If you’re good at maths, this is the formula if you want to do the sums yourself - 

Roof Pitch = 1 ÷ Tangent (Rise ÷ Run)


Roof pitch measurer

If maths and measuring aren’t your strong point, you can get tools which look like spirit levels which will do the job for you.   You can get analogue and digital devices - digital ones are more expensive but are easier to read - worth the investment if you’re going to need to measure many different roofs regularly

Mobile Apps

New technology and smartphones have given rise to many pitch calculating apps, these are available for iPhone and Android with some of the more advanced one’s even using the phone’s gyroscope in conjunction with the camera.  If you just need a quick estimate and don’t want to climb onto the roof, an app like this is a good option.