Here, we’ve laid out everything you need to know to accurately calculate your roof’s pitch for when you need roof repair or replacement. You need this figure if you’re planning on adding vents, windows, or other accessories to your roof.You can use the information to determine whether you have the best roof pitch for your climate zone.It helps you figure out how many rafters you need to hold up your roof.It’s the first step in figuring out how many roofing materials you need to cover your roof, and how much these materials will ultimately cost you.What if we told you that you could use those math skills to calculate the pitch of your roof? Knowing how to calculate your roof pitch can come in handy for a variety of reasons: Do you remember sitting in your high school algebra class, watching your teacher write sums and figures on the board, wondering, “When am I ever going to use this in real life?”