Whether you’re planning a new roof, buying roofing materials, or just checking your contractor’s quote, knowing your roof pitch is essential. Our free Roof Pitch Calculator gives you the pitch ratio, angle in degrees, and rafter length in seconds — no trigonometry needed.
Roof Pitch Calculator
Roof Pitch Calculator
What Is Roof Pitch?
Roof pitch is the measure of how steep a roof is. It's expressed as a ratio of rise over run — for example, a 6:12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. This number affects everything from how much roofing material you need to what type of shingles are suitable.
Roof Pitch Formula
The formulas used in this calculator:
- Pitch Ratio = (Rise ÷ Run) × 12
- Angle (°) = arctan(Rise ÷ Run) × (180 ÷ π)
- Rafter Length = √(Rise² + Run²)
Roof Pitch Chart (Common Pitches)
| Pitch Ratio | Angle | Type | Common Use |
|---|---|---|---|
| 2:12 | 9.5° | Low | Sheds, porches |
| 4:12 | 18.4° | Moderate | Residential homes |
| 6:12 | 26.6° | Standard | Most common residential |
| 8:12 | 33.7° | Steep | Cottages, cabins |
| 12:12 | 45° | Very Steep | Victorian, A-frame |
How to Measure Roof Pitch Yourself
- Get a level and a tape measure. You'll need an 18-inch or longer level.
- Place the level horizontally against the roof surface near the ridge.
- Measure 12 inches along the level from where it touches the roof.
- Measure vertically from the 12-inch mark down to the roof surface — that number is your rise.
- Enter rise = your measurement, run = 12 in the calculator above.
Why Roof Pitch Matters
Roof pitch affects several practical factors:
- Material choice: Low-pitch roofs (under 4:12) need special waterproofing; standard shingles require at least 2:12 pitch.
- Cost: Steeper roofs need more material and labor — typically 15–25% more expensive than a 4:12 pitch.
- Weather performance: Higher pitches shed snow and rain faster, reducing leak risk.
- Attic space: Higher pitch = more usable attic space.
Frequently Asked Questions
What is the most common roof pitch?
The most common residential roof pitch in the US is 4:12 to 6:12. This range balances material cost, weather performance, and curb appeal.
What pitch is too steep to walk on?
Roofs steeper than 7:12 (30°) are generally considered unsafe to walk on without proper fall protection equipment.
Can I use a metal roof on a low-pitch roof?
Yes. Standing-seam metal roofing works on pitches as low as 1:12, making it ideal for low-slope applications where asphalt shingles aren't suitable.
How does pitch affect roofing material quantity?
A steeper roof has more surface area than the same footprint at a lower pitch. A 12:12 pitch roof has about 41% more surface area than a flat version of the same building footprint.