Quick answer
Roof pitch converts to degrees with the arctangent of rise ÷ run: 4/12 = 18.43°, 6/12 = 26.57°, 8/12 = 33.69° and 12/12 = 45.00°. Going the other way, rise per 12 inches = 12 × tan(angle).
About the Roof Pitch to Degrees Chart
A converter between the two ways roof slope is usually written — pitch in inches per foot (x/12) and degrees — that works in both directions and shows its trigonometry. Below it sits a complete chart from ¼/12 to 24/12 with percent grade, pitch multiplier and hip/valley factor, and a reverse table from common angles back to pitch.
How to use it
Pick Pitch → degrees and enter the rise per 12 inches of run, or any rise and run measured in the same unit. Or pick Degrees → pitch and type the angle. The answer updates as you type, with each step of the calculation listed underneath.
When you need more than the angle — rafter length, roof area, squares or shingle bundles — carry on in the full roof pitch calculator.
Use cases
- Phone and angle-finder readings. Convert a measured angle into the x/12 pitch that installation guides and inspectors expect.
- Solar and skylight planning. Express the roof's slope in degrees to compare with a panel or window tilt specification.
- Old drawings. Translate a slope written as a percent grade or as a ratio into a modern x/12 pitch.
- Quick lookups on site. Keep the chart open to read off multipliers without doing the square roots by hand.
Roof pitch to degrees: the formula
Roof pitch is rise over run, usually written per 12 inches of run: a 4/12 roof rises 4 inches for every 12 inches across. To turn that into an angle, take the arctangent of the ratio:
angle in degrees = atan(rise ÷ run) × 180 ÷ π
For a 4/12 pitch that is atan(4 ÷ 12) = atan(0.3333) = 18.43°. Going the other way, pitch = tan(angle) × 12, so a 30° roof is tan(30°) × 12 = 6.93, or just under 7/12. Calculators and spreadsheets do the trig for you; the converter above shows both directions and the steps.
The relationship is not linear. Each extra inch of rise adds fewer degrees as the roof gets steeper: going from 1/12 to 2/12 adds 4.7°, while going from 11/12 to 12/12 adds only 2.5°. That is why you cannot simply multiply the pitch by a constant to get degrees.
Complete roof pitch chart
Angle, slope percentage, pitch multiplier (for converting plan area to roof area) and the hip/valley factor, from very low-slope roofs to steep mansard-style pitches.
| Pitch | Degrees | Slope % | Multiplier | Hip/valley |
|---|---|---|---|---|
| ¼/12 | 1.19° | 2.1% | 1.000 | 1.414 |
| ½/12 | 2.39° | 4.2% | 1.001 | 1.415 |
| ¾/12 | 3.58° | 6.3% | 1.002 | 1.416 |
| 1/12 | 4.76° | 8.3% | 1.003 | 1.417 |
| 1½/12 | 7.13° | 12.5% | 1.008 | 1.420 |
| 2/12 | 9.46° | 16.7% | 1.014 | 1.424 |
| 2½/12 | 11.77° | 20.8% | 1.021 | 1.429 |
| 3/12 | 14.04° | 25% | 1.031 | 1.436 |
| 3½/12 | 16.26° | 29.2% | 1.042 | 1.444 |
| 4/12 | 18.43° | 33.3% | 1.054 | 1.453 |
| 4½/12 | 20.56° | 37.5% | 1.068 | 1.463 |
| 5/12 | 22.62° | 41.7% | 1.083 | 1.474 |
| 5½/12 | 24.62° | 45.8% | 1.100 | 1.487 |
| 6/12 | 26.57° | 50% | 1.118 | 1.500 |
| 6½/12 | 28.44° | 54.2% | 1.137 | 1.514 |
| 7/12 | 30.26° | 58.3% | 1.158 | 1.530 |
| 7½/12 | 32.01° | 62.5% | 1.179 | 1.546 |
| 8/12 | 33.69° | 66.7% | 1.202 | 1.563 |
| 9/12 | 36.87° | 75% | 1.250 | 1.601 |
| 10/12 | 39.81° | 83.3% | 1.302 | 1.641 |
| 11/12 | 42.51° | 91.7% | 1.357 | 1.685 |
| 12/12 | 45.00° | 100% | 1.414 | 1.732 |
| 14/12 | 49.40° | 116.7% | 1.537 | 1.833 |
| 16/12 | 53.13° | 133.3% | 1.667 | 1.944 |
| 18/12 | 56.31° | 150% | 1.803 | 2.062 |
| 20/12 | 59.04° | 166.7% | 1.944 | 2.186 |
| 22/12 | 61.39° | 183.3% | 2.088 | 2.315 |
| 24/12 | 63.43° | 200% | 2.236 | 2.449 |
Degrees to roof pitch
If your plans, an angle finder or a phone app give you degrees, use this table — or the converter's "Degrees → pitch" mode for any value.
| Angle | Exact pitch | Nearest ¼ |
|---|---|---|
| 5° | 1.05/12 | 1/12 |
| 10° | 2.12/12 | 2/12 |
| 14° | 2.99/12 | 3/12 |
| 15° | 3.22/12 | 3¼/12 |
| 18.43° | 4.00/12 | 4/12 |
| 20° | 4.37/12 | 4¼/12 |
| 22.5° | 4.97/12 | 5/12 |
| 25° | 5.60/12 | 5½/12 |
| 26.57° | 6.00/12 | 6/12 |
| 30° | 6.93/12 | 7/12 |
| 33.69° | 8.00/12 | 8/12 |
| 35° | 8.40/12 | 8½/12 |
| 40° | 10.07/12 | 10/12 |
| 45° | 12.00/12 | 12/12 |
| 50° | 14.30/12 | 14¼/12 |
| 55° | 17.14/12 | 17¼/12 |
| 60° | 20.78/12 | 20¾/12 |
Common pitches and what they are used for
- ¼/12 to 2/12 (1.2°–9.5°) — low-slope and "flat" roofs on commercial buildings, porches and additions. They need membrane roofing (TPO, EPDM, modified bitumen) or standing-seam metal rated for the slope.
- 3/12 to 4/12 (14°–18.4°) — ranch houses, sheds and porch roofs. Asphalt shingles are allowed from 2/12 but need double underlayment below 4/12 under the IRC.
- 5/12 to 7/12 (22.6°–30.3°) — the most common range for houses in the US: easy to shingle, walkable with care, good drainage.
- 8/12 to 12/12 (33.7°–45°) — steeper roofs on colonial, Tudor and many two-story homes; more attic space, faster snow shedding, and roof jacks for the crew.
- Above 12/12 — steeper than 45°, seen on A-frames, gothic and mansard roofs; slower and costlier to roof.
Pitch, slope and angle are three ways to say the same thing
US framers and roofers say pitch as rise in 12 (6/12). Engineers and some plans use a percentage grade (50% for 6/12, because 6 ÷ 12 = 0.5). Architects and solar installers often use degrees (26.57°). Older texts sometimes define "pitch" as rise over the full span, so a 6/12 roof would be called a ¼ pitch — if a number looks off by a factor of two, that is usually why. The chart above converts between all of them.
Measuring the pitch of an existing roof
Hold a level flat against the roof or the underside of a rafter, measure 12 inches along it, and measure straight down to the roof from that point: the distance in inches is the rise per 12. An angle finder or a phone level gives degrees directly. For area, rafters and shingle counts, continue in the full roof pitch calculator.
Sources
Frequently asked questions
What is a 4/12 roof pitch in degrees?
18.43°. The roof rises 4 inches for every 12 inches of run, and atan(4 ÷ 12) = 18.43°. It is a 33.3% slope with a pitch multiplier of 1.054.
What is a 6/12 roof pitch in degrees?
26.57°. A 6/12 roof is a 50% slope; its pitch multiplier is 1.118, meaning roof area is about 11.8% larger than the footprint.
What pitch is a 30 degree roof?
About 6.93/12, which roofers round to 7/12. Use pitch = tan(angle) × 12.
What roof pitch is 45 degrees?
12/12 — the rise equals the run. It is a 100% slope with a multiplier of 1.414.
How do I convert roof pitch to a percentage?
Divide the rise by the run and multiply by 100. A 4/12 roof is 33.3%, 6/12 is 50% and 12/12 is 100%.
What is the lowest pitch for shingles?
2/12 (9.46°) under the 2021 International Residential Code, with double underlayment required up to 4/12. Below that, use a low-slope roofing system.
Disclaimer. Conversions are exact trigonometry rounded for display. Minimum slopes for roofing materials follow the 2021 IRC; your local code and the manufacturer's instructions take precedence.
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