What does a roof pitch calculator chart show?
Short answer. A roof pitch chart lists each pitch with its angle in degrees, its slope multiplier for calculating roof area, and practical notes like whether shingles are allowed and whether the roof is walkable. It lets you look up a value instead of calculating it.
Pitch, angle, multiplier and practical notes
- 2/12: 9.5 degrees, multiplier 1.014. Lowest pitch allowed for asphalt shingles; double underlayment required.
- 3/12: 14.0 degrees, 1.031. Shingles with double underlayment; common on porches.
- 4/12: 18.4 degrees, 1.054. Standard shingle installation starts here.
- 5/12: 22.6 degrees, 1.083. Easy to walk; common on ranch homes.
- 6/12: 26.6 degrees, 1.118. Walkable for roofers; very common.
- 7/12: 30.3 degrees, 1.158. Upper end of comfortably walkable.
- 8/12: 33.7 degrees, 1.202. Steep; fall protection and roof jacks typical.
- 9/12: 36.9 degrees, 1.250. Steep; steep charges common on estimates.
- 10/12: 39.8 degrees, 1.302. Very steep.
- 11/12: 42.5 degrees, 1.357. Very steep.
- 12/12: 45.0 degrees, 1.414. Steep front gables on many newer homes.
How to use it
Find your pitch, then multiply the flat footprint area of that roof section (including overhangs) by the multiplier to get the true surface area. Example: a 1,500 square foot footprint at 8/12 is 1,500 × 1.202 = 1,803 square feet, about 18 squares before waste.
Where pitches change cost
Steep charges usually begin around 7/12 or 8/12 and increase again for very steep roofs, because crews move slower and need more safety setup. See how roofers measure a roof and roof replacement cost in Georgia.