Roofing and siding calculators
Find your roof pitch and roof area, or lay out board and batten on a wall or gable. Each calculator explains the math and the code minimums behind it.
Common roof pitches
| Pitch | Angle | Area multiplier |
|---|---|---|
| 4/12 | 18.4° | 1.054 |
| 6/12 | 26.6° | 1.118 |
| 8/12 | 33.7° | 1.202 |
| 12/12 | 45.0° | 1.414 |
See every pitch from 1/12 to 24/12, and the minimum pitch for shingles, tile and metal, in the roof pitch chart. Asphalt shingles need at least 2/12 under the International Residential Code; standing seam metal can go down to 1/4/12.
Batten and board sizes
Nominal lumber is smaller than its name: a 1 × 3 batten is 2 1/2 inches wide and a 1 × 8 board is 7 1/4 inches. The board and batten calculator uses the actual width, and the linear feet calculator converts square feet of siding to linear feet.
Sources
- Minimum slopes for asphalt shingles and metal panels: ICC, 2021 International Residential Code, R905.2.2 Slope; ICC, 2021 IRC, R905.10.2 Metal roof panel slope
- Actual sizes of nominal boards: NIST, PS 20-20 American Softwood Lumber Standard, Table 3
Last reviewed November 9, 2026. Found a wrong figure? Tell us.