Roof Pitch Calculator
Calculate roof pitch from rise and run.
Last updated 2026-08-21
What Is a Roof Pitch Calculator?
A roof pitch calculator converts the rise and run of your roof into pitch, slope percentage, and angle in degrees. Pitch tells you how steep your roof is, which drives everything from the amount of roofing material to the type of underlayment and how safely you can walk on it. Homeowners use it to describe their roof to contractors and to understand why a steeper roof costs more to cover.
How It Works
Pitch (in 12) = Rise ÷ Run × 12. Angle = atan(Rise ÷ Run). Slope % = Rise ÷ Run × 100.
Example
For a 6 in rise over 12 in run: pitch = 6 in 12, angle ≈ 26.6°, slope = 50%.
How to Calculate
- Measure the vertical rise in inches over a known horizontal run. A common run to use is 12 in, which equals 1 ft of horizontal distance.
- Enter the rise, such as 6 in, over a run of 12 in. The calculator divides rise by run and multiplies by 12 to give a pitch of 6 in 12.
- Read the slope as a percentage. A 6 in rise over a 12 in run equals 50% slope.
- Check the angle in degrees. A 6 in 12 roof has an angle of about 26.6 degrees.
- Use the pitch multiplier from the results to estimate the true roof surface area for material ordering.
Pitch, Slope, and Angle Reference
| Pitch | Slope % | Angle (deg) | Pitch Multiplier |
|---|---|---|---|
| 2 in 12 | 16.7% | 9.5 | 1.01 |
| 4 in 12 | 33.3% | 18.4 | 1.05 |
| 6 in 12 | 50% | 26.6 | 1.12 |
| 8 in 12 | 66.7% | 33.7 | 1.20 |
| 10 in 12 | 83.3% | 39.8 | 1.30 |
| 12 in 12 | 100% | 45.0 | 1.41 |
Sources
Frequently Asked Questions
What does "4 in 12" mean?
It means the roof rises 4 inches for every 12 inches (1 foot) of horizontal run.
What is a low-slope roof?
Slopes under about 3 in 12 are considered low-slope and often require specialized roofing systems.
Why does pitch matter?
Pitch determines the roof surface area, the type of underlayment needed, and walking safety.
Estimate the cost with the Roofing Cost Calculator or browse Roofing Calculators