From footprint to squares
A roofing square is 100 square feet of roof surface. The satellite outline gives the footprint, which is smaller than the surface because the roof slopes. To get squares:
- Outline the roof on the map, eaves included, and read the footprint
- Multiply by the pitch factor for your roof (table below)
- Divide by 100 to get squares
- Add 10 to 15 percent for waste, hips and valleys when you order material
Pitch factors
| Pitch (rise per 12 in run) | Multiply footprint by |
|---|---|
| 3/12 | 1.03 |
| 4/12 | 1.05 |
| 5/12 | 1.08 |
| 6/12 | 1.12 |
| 7/12 | 1.16 |
| 8/12 | 1.20 |
| 9/12 | 1.25 |
| 10/12 | 1.30 |
| 12/12 | 1.41 |
Example: a 2,000 square foot footprint at 6/12 is about 2,240 square feet of roof, or 22.4 squares. With 12 percent waste you order about 25 squares of shingles.
The map cannot tell you the pitch. Count it on the roof with a level and a tape, or ask the roofer who inspects it. The calculator above does not detect pitch either; its rates assume a walkable roof, and you add the steep pitch extra if yours is 8/12 or steeper.
What the price means
At the sample shingle rate, that 2,000 square foot footprint comes to about $13,500, shown as a range of $12,100 to $15,600. That works out to about $600 per installed square, inside the usual US range. Read how much to charge per square for how roofers set that number, and satellite estimates vs on the roof for where the map is close and where it is not.
For roofing companies
Put this calculator on your site and every lead arrives with the address and the outlined footprint, so you know the size of the job before you load the ladder. The roof replacement cost calculator is the same tool set up for homeowners comparing materials.