Roof pitch chart
Roof pitch is the rise in inches for every 12 inches of run. A 6/12 roof rises 6 inches per foot, which is a 26.6 degree angle and a 50 percent slope. The chart below converts every common pitch to degrees, percent and the multiplier for roof area.
Roof pitch to degrees chart
| Pitch | Angle | Slope | Multiplier | Roof per 1,000 ft² footprint |
|---|---|---|---|---|
| 1/12 | 4.8° | 8.3% | 1.003 | 1,003 ft² |
| 2/12 | 9.5° | 16.7% | 1.014 | 1,014 ft² |
| 3/12 | 14.0° | 25.0% | 1.031 | 1,031 ft² |
| 4/12 | 18.4° | 33.3% | 1.054 | 1,054 ft² |
| 5/12 | 22.6° | 41.7% | 1.083 | 1,083 ft² |
| 6/12 | 26.6° | 50.0% | 1.118 | 1,118 ft² |
| 7/12 | 30.3° | 58.3% | 1.158 | 1,158 ft² |
| 8/12 | 33.7° | 66.7% | 1.202 | 1,202 ft² |
| 9/12 | 36.9° | 75.0% | 1.250 | 1,250 ft² |
| 10/12 | 39.8° | 83.3% | 1.302 | 1,302 ft² |
| 11/12 | 42.5° | 91.7% | 1.357 | 1,357 ft² |
| 12/12 | 45.0° | 100.0% | 1.414 | 1,414 ft² |
| 14/12 | 49.4° | 116.7% | 1.537 | 1,537 ft² |
| 16/12 | 53.1° | 133.3% | 1.667 | 1,667 ft² |
| 18/12 | 56.3° | 150.0% | 1.803 | 1,803 ft² |
| 20/12 | 59.0° | 166.7% | 1.944 | 1,944 ft² |
| 24/12 | 63.4° | 200.0% | 2.236 | 2,236 ft² |
Angle = arctan(rise ÷ 12). Slope percent = rise ÷ 12 × 100. Multiplier = √(1 + (rise ÷ 12)²), the length of roof surface for each foot of horizontal run. For a pitch not in the chart, or to work back from an angle, use the roof slope calculator.
How to measure roof pitch
- From the attic or a ladder at the roof edge, hold a level horizontally against the underside of a rafter or the roof surface.
- Mark 12 inches along the level from the point where it touches.
- Measure straight up from the 12 inch mark to the rafter or roof. That number in inches is the rise.
- Write it as rise/12. A 5 inch measurement means a 5/12 pitch.
Already know the angle? Find the closest angle in the chart, or switch the calculator to angle mode.
Minimum roof pitch by material
The 2021 International Residential Code sets these minimums. Local codes and manufacturer instructions can require more.
| Roof covering | Minimum pitch | IRC section |
|---|---|---|
| Asphalt shingles | 2/12 (double underlayment up to 4/12) | R905.2.2 |
| Clay and concrete tile | 2 1/2/12 (double underlayment up to 4/12) | R905.3.2 |
| Wood shingles | 3/12 | R905.7.2 |
| Metal panels, lapped seams, no sealant | 3/12 | R905.10.2 |
| Metal panels, lapped seams with sealant | 1/2/12 | R905.10.2 |
| Standing seam metal | 1/4/12 | R905.10.2 |
Using the multiplier for roof area
Roofing is sold by the square (100 ft²). Multiply the footprint of the house, overhangs included, by the multiplier for your pitch to get roof area, then divide by 100 for squares.
Worked example. A 40 × 30 ft house with 1 ft overhangs has a 42 × 32 ft footprint: 1,344 ft². At 6/12 the multiplier is 1.118, so the roof is about 1,503 ft², or 15 squares before waste.
Fascia, drip edge and gutters are bought by length; total them with the linear feet calculator. For siding the gable ends, the board and batten calculator lays out the battens.
Roof pitch questions
What is a 4/12 roof pitch in degrees?
A 4/12 pitch is 18.4 degrees, a 33.3 percent slope.
What angle is an 8/12 roof?
An 8/12 pitch is 33.7 degrees, a 66.7 percent slope. Each foot of run adds 1.202 ft of roof surface.
What is the lowest pitch for a shingle roof?
The International Residential Code allows asphalt shingles from 2/12 up, with double underlayment between 2/12 and 4/12.
How do I use the roof area multiplier?
Multiply the house footprint, including overhangs, by the multiplier for your pitch. A 1,500 ft² footprint at 6/12 (× 1.118) has about 1,677 ft² of roof.
Sources
- Asphalt shingles 2:12 or steeper, double underlayment from 2:12 to 4:12: ICC, 2021 International Residential Code, R905.2.2 Slope
- Clay and concrete tile 2 1/2:12 or steeper: ICC, 2021 IRC, R905.3.2 Clay and concrete tile deck slope
- Wood shingles 3:12 or steeper: ICC, 2021 IRC, R905.7.2 Wood shingle deck slope
- Metal roof panels: 3:12 for lapped seams without sealant, 1/2:12 with sealant, 1/4:12 for standing seam: ICC, 2021 IRC, R905.10.2 Metal roof panel slope
Last reviewed November 9, 2026. Found a wrong figure? Tell us.