Roof Pitch Multiplier Chart
How much bigger a sloped roof is than the footprint under it. Multiply the ground area by the factor for your pitch to get the real surface to cover — skip this and a steep roof comes up short by a fifth.
Source data and formula checked · How we check
Roof Pitch Multiplier Chart reads roofing squares straight off roof pitch, for 24 values from 1 to 24. Every row is computed from the same formula the calculator uses, not measured or copied from another table, so a value between two rows can be worked out the same way. The formula is the one published by Asphalt Roofing Manufacturers Association.
| Roof pitch (/12) | Roofing squares | Pitch multiplier | Bundles (three per square) |
|---|---|---|---|
| 1 | 17.66 squares | 1 | 53 bundles |
| 2 | 17.84 squares | 1.01 | 54 bundles |
| 3 | 18.14 squares | 1.03 | 55 bundles |
| 4 | 18.55 squares | 1.05 | 56 bundles |
| 5 | 19.07 squares | 1.08 | 58 bundles |
| 6 | 19.68 squares | 1.12 | 60 bundles |
| 7 | 20.38 squares | 1.16 | 62 bundles |
| 8 | 21.15 squares | 1.2 | 64 bundles |
| 9 | 22.00 squares | 1.25 | 66 bundles |
| 10 | 22.91 squares | 1.3 | 69 bundles |
| 11 | 23.88 squares | 1.36 | 72 bundles |
| 12 | 24.89 squares | 1.41 | 75 bundles |
| 13 | 25.95 squares | 1.47 | 78 bundles |
| 14 | 27.04 squares | 1.54 | 82 bundles |
| 15 | 28.17 squares | 1.6 | 85 bundles |
| 16 | 29.33 squares | 1.67 | 88 bundles |
| 17 | 30.52 squares | 1.73 | 92 bundles |
| 18 | 31.73 squares | 1.8 | 96 bundles |
| 19 | 32.96 squares | 1.87 | 99 bundles |
| 20 | 34.21 squares | 1.94 | 103 bundles |
| 21 | 35.47 squares | 2.02 | 107 bundles |
| 22 | 36.75 squares | 2.09 | 111 bundles |
| 23 | 38.05 squares | 2.16 | 115 bundles |
| 24 | 39.35 squares | 2.24 | 119 bundles |
Questions people actually ask
- How do I read the Roof Pitch Multiplier Chart?
- Find your roof pitch in the first column and read across. At 1 the roofing squares is 17.66 squares; at 24 it is 39.35 squares. The table runs from 1 to 24 in 24 rows.
- Can I read between two rows?
- Not by splitting the difference. The roofing squares does not change by the same amount from row to row, so the midpoint of two rows is not the answer for the midpoint of two roof pitch values. Put the exact figure into the calculator instead — it uses the same formula that produced every row here.
- What if my roof pitch is outside the table?
- The chart covers 1 to 24, which is the range people actually look up. Anything above or below goes into the calculator, which takes any figure and shows each step of the working rather than only the result. Open the roofing calculator.
- Where do these numbers come from?
- Every row is computed at build time from the formula published by Asphalt Roofing Manufacturers Association, by the same code behind the calculator — not transcribed from another table, which is how a rounding error in one chart ends up in twenty.
Need a different number?
The chart covers the common values. For anything between the rows, the roofing calculator takes any figure and shows the working.
Source: Asphalt Roofing Manufacturers Association, National Roofing Contractors Association