How to measure roof pitch
Hold a spirit level horizontally against the roof surface or a rafter, mark 12 inches along it, and measure straight up (or down) from that mark to the roof. That vertical distance is the rise per 12 inches of run, so a measurement of 6 inches is a 6/12 pitch. You can also enter any rise and run, such as the total rise and half the span of a gable, and the calculator converts it.
Common roof pitches
| Pitch | Angle | Multiplier |
|---|---|---|
| 3/12 | 14.0° | 1.031 |
| 4/12 | 18.4° | 1.054 |
| 6/12 | 26.6° | 1.118 |
| 8/12 | 33.7° | 1.202 |
| 10/12 | 39.8° | 1.302 |
| 12/12 | 45.0° | 1.414 |
What is the pitch multiplier?
A sloped roof has more surface than the flat area it covers. The multiplier is the length of the sloped surface for each foot of horizontal run. Multiply the footprint of the roof, including overhangs, by it to get the real roof area. Roofing materials are often sold by the square, which is 100 square feet.
Frequently asked questions
What pitch do asphalt shingles need?
Shingle makers typically require at least 2/12, and roofs between 2/12 and 4/12 need extra underlayment. Check the instructions for the product you use.
Is roof pitch the same as roof slope?
People use both words for the same idea. Pitch is usually written as rise per 12 inches of run (6/12); slope is often given as an angle or a percentage.
How many squares is my roof?
Enter the footprint including overhangs. For example, a 1,000 square foot footprint with a 6/12 pitch is about 1,118 square feet of roof, or 11.2 squares.