How to Use a Speed Square
Get the most out of this handy little triangle
IntroductionSpeed squares aren't just for marking 90- and 45-degree angles when you're cutting 2x4s. You can use a speed square to find roof pitches, guide your circular saw and more—including marking any angle from 0 to 90 degrees.
- Circular saw
- Speed square
What is a Speed Square?
Ever wonder why every contractor you see has a triangular square stuck in his tool belt? This cheap, handy little tool is called either a rafter square or a speed square, and it can offer you the biggest bang for the buck in your toolbox. This tool has dozens of uses; here are three of our favorites.
Project step-by-step (3)
Find Roof Pitch
- Place the pivot point against the shingles.
- Then place a torpedo level on the fat base of the speed square.
- Adjust the square until the level is level.
- Read the pitch on the side of the speed square.
- Note: The pitch tells you the amount of vertical rise (in inches) for every 12 inches of run.
- Swing the speed square until you read the desired angle on the board’s edge.
- Mark the angle on the board.
- Note: The example shows a 33-1/2 degree angle.
Guide Saw Cuts
- Cut 45- and 90-degree angles by using the speed square as a guide.
- Pro tip: This method works better (and safer) when right-handed users have a circular saw with the motor to the right of the blade (like in the photo).