Roof pitch calculator and chart
A 6:12 roof pitch is 26.6 degrees, a 50.0 percent slope, and a pitch multiplier of 1.1180. The chart below converts every pitch from 1:12 to 24:12 the same way, so you can read the angle and the multiplier without doing the trigonometry.
Roof pitch is written as rise over run: the inches a roof rises for every 12 inches it runs horizontally. A 4:12 roof rises 4 inches per foot of run. The same pitch can be expressed three other ways, and roofing, framing, and estimating each tend to want a different one.
Roof pitch calculator
Enter the rise and the run and this works out the pitch, the angle in degrees, the percent slope, the pitch multiplier, and the rafter length for that run. Any units work as long as both boxes use the same ones, because every result comes from the ratio.
How far the roof goes up.
How far it goes across. Roofing uses 12.
Square feet, to get the sloped area.
- Pitch
- 6:12
- Angle
- 26.6 deg
- Slope
- 50%
- Pitch multiplier
- 1.1180
- Rafter length
- 13.42
- Sloped roof area
- -
The multiplier converts a flat footprint into actual sloped roof area, which is what estimating needs. It is the rafter length divided by the run. These figures are reference math for planning, not a measurement of your roof and not a material order.
Roof pitch to degrees conversion chart
| Pitch | Angle (degrees) | Slope (percent) | Pitch multiplier |
|---|---|---|---|
| 1:12 | 4.8° | 8.3% | 1.0035 |
| 2:12 | 9.5° | 16.7% | 1.0138 |
| 3:12 | 14.0° | 25.0% | 1.0308 |
| 4:12 | 18.4° | 33.3% | 1.0541 |
| 5:12 | 22.6° | 41.7% | 1.0833 |
| 6:12 | 26.6° | 50.0% | 1.1180 |
| 7:12 | 30.3° | 58.3% | 1.1577 |
| 8:12 | 33.7° | 66.7% | 1.2019 |
| 9:12 | 36.9° | 75.0% | 1.2500 |
| 10:12 | 39.8° | 83.3% | 1.3017 |
| 11:12 | 42.5° | 91.7% | 1.3566 |
| 12:12 | 45.0° | 100.0% | 1.4142 |
| 13:12 | 47.3° | 108.3% | 1.4743 |
| 14:12 | 49.4° | 116.7% | 1.5366 |
| 15:12 | 51.3° | 125.0% | 1.6008 |
| 16:12 | 53.1° | 133.3% | 1.6667 |
| 17:12 | 54.8° | 141.7% | 1.7341 |
| 18:12 | 56.3° | 150.0% | 1.8028 |
| 19:12 | 57.7° | 158.3% | 1.8727 |
| 20:12 | 59.0° | 166.7% | 1.9437 |
| 21:12 | 60.3° | 175.0% | 2.0156 |
| 22:12 | 61.4° | 183.3% | 2.0883 |
| 23:12 | 62.4° | 191.7% | 2.1619 |
| 24:12 | 63.4° | 200.0% | 2.2361 |
How to convert roof pitch to degrees
Take the arctangent of rise divided by run. For a 4:12 pitch that is arctan(4 / 12), which is 18.4 degrees. The run is always 12, so only the rise changes.
Two anchors worth memorising: a 12:12 roof is exactly 45 degrees, because it rises as much as it runs, and a 6:12 roof is 26.6 degrees, which is the most common residential pitch in the chart above.
What the pitch multiplier is for
The pitch multiplier, also called the roof pitch factor or slope factor, converts the flat footprint of a building into the actual sloped area of its roof. Multiply the footprint square footage by the multiplier for that pitch.
A 2,000 square foot footprint on a 6:12 roof is about 2,236 square feet of roof surface, because 2,000 multiplied by 1.1180 is 2,236. On a 12:12 roof the same footprint becomes about 2,828 square feet. This is why two houses with identical floor plans can need very different quantities of material.
Reading pitch off a roof instead of a chart
A chart only helps once you already know the pitch. There are three ways to measure roof pitch in the first place, and Pitch Please reads it directly: rest the phone on a rafter, a roof surface, or any slope and Direct Mode shows the pitch and the angle together. Camera Mode reads a roof from the ground by lining a guide up with the roof edge, so you can take a reading without getting on a ladder.
It works offline, needs no account, and shows imperial and international units side by side. What it does not do is calibrate to a reference surface, so on an unusually uneven rafter take a second reading to confirm.
See how the Pitch Please roof pitch app works, or read the detail on measuring roof pitch from the ground with Camera Mode.
Frequently asked questions
What is a 6/12 roof pitch in degrees?
A 6:12 roof pitch is 26.6 degrees. It rises 6 inches for every 12 inches of horizontal run, which is a 50.0 percent slope, and its pitch multiplier is 1.1180.
What is a roof pitch multiplier?
The pitch multiplier, also called the roof pitch factor or slope factor, converts a flat footprint area into actual sloped roof area. Multiply the footprint square footage by the multiplier for the pitch. A 6:12 roof uses 1.1180, so a 2,000 square foot footprint is about 2,236 square feet of roof surface.
How do I convert roof pitch to degrees?
Take the arctangent of the rise divided by the run. For a 4:12 pitch that is arctan(4/12), which is 18.4 degrees. The chart on this page lists every pitch from 1:12 to 24:12 already converted.
What counts as a steep-slope roof?
Pitches above 12:12 are steep-slope. A 12:12 roof is 45 degrees, and anything steeper than that rises more than it runs.
Can I measure roof pitch with my phone instead of reading a chart?
Yes. Pitch Please reads pitch directly from device tilt when you rest the phone on a rafter or roof surface, and Camera Mode reads it from the ground by lining a guide up with the roof edge. The app shows pitch and degrees together, so you do not need to convert by hand.