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Roof pitch calculator

Your roof pitch from a rise and run or an angle, with the angle, pitch factor and slope.

Example sizes, change them. The answer updates as you type.

I know the

The vertical drop over your run. Measure from inside the attic, or with a level from a ladder at the eave.

Level distance. 12 inches gives the pitch directly.

= 6/12 pitch Full breakdown below
Your roof
6/12 pitch
6 inches of rise per 12 inches of run
26.6° angle
1.118 pitch factor
50% slope

Not yet fact-checkedMethod and sources

Your roof pitch Drawing of a right triangle: a rise of 6 in over a run of 12 in, a 6/12 pitch with an angle of 26.6 degrees. 12 in 6 in 26.6°
Redraws as you typedrawn to scale

Your roof is a 6/12 pitch (26.6 degrees): multiply the footprint by 1.118 for roof area.

Common roof pitches

PitchAngleFactor
1/124.8°1.003
2/129.5°1.014
3/1214.0°1.031
4/1218.4°1.054
5/1222.6°1.083
6/1226.6°1.118
7/1230.3°1.158
8/1233.7°1.202
9/1236.9°1.250
10/1239.8°1.302
11/1242.5°1.357
12/1245.0°1.414

How we worked it out

  1. 6 in ÷ 12 in = 0.5
  2. 0.5 × 12 = 6, so a 6/12 pitch
  3. Angle: arctan(0.5) = 26.6°
  4. Pitch factor: √(1 + 0.5²) = 1.118
  5. Slope: 0.5 × 100 = 50%

How to measure pitch safely from inside the attic or with a level on a ladder at the eaveDraft copy

(no roof walking advice).

Pitch table 1/12 to 12/12Draft copy

angle, factor, percent (derived; 4/12 to 12/12 factors match IKO's table).

What pitch means for shinglesDraft copy

(IRC R905.2.2), ad slot 1.

Worked examples

Rise 6 inches over a 12 inch run

I know the Rise and runRise 6 inRun 12 inAngle 26.57 deg

Your roof is a 6/12 pitch (26.6 degrees): multiply the footprint by 1.118 for roof area.

Roof pitch
6/12
Angle
26.6
Pitch factor (roof area multiplier)
1.118
Slope
50.0%
For asphalt shingles

Rise 9 inches over a 24 inch level

I know the Rise and runRise 9 inRun 24 inAngle 26.57 deg

Your roof is a 4.5/12 pitch (20.6 degrees): multiply the footprint by 1.068 for roof area.

Roof pitch
4.5/12
Angle
20.6
Pitch factor (roof area multiplier)
1.068
Slope
37.5%
For asphalt shingles

A 45 degree roof

I know the AngleRise 6 inRun 12 inAngle 45 deg

Your roof is a 12/12 pitch (45.0 degrees): multiply the footprint by 1.414 for roof area.

Roof pitch
12/12
Angle
45.0
Pitch factor (roof area multiplier)
1.414
Slope
100.0%
For asphalt shingles

Method and sources

Each calculator uses the standard formula and the manufacturer's own figures, such as bag yields, and rounds up where running short would cost you a trip. Every step is shown. Cost ranges come from named surveys with the date we checked them. Spot something wrong? Tell us and we will fix it and note the change.

  • Pitch is rise in inches per 12 inches of horizontal run (NRCA).
  • Pitch factor = square root of (1 + (rise / 12) squared).
  • Shingle limits from IRC R905.2.2: 2/12 minimum; double underlayment below 4/12.