Estimate how many shingles (roofing squares) you need and the total cost to replace a roof, based on roof size, pitch, and shingle type.
| Roof area (footprint) | |
| Actual roof surface area | |
| Squares needed (incl. 10% waste) | |
| Estimated material cost | |
| Estimated labor cost |
Roofing is priced in "squares" — one square covers 100 square feet of actual roof surface. Because a sloped roof has more surface area than its flat footprint, a pitch multiplier is applied first.
The 1.10 factor adds 10% for waste from cuts, valleys, and overlaps — a standard estimating margin used by roofing contractors.
| Type | Cost per square |
|---|---|
| 3-tab asphalt | ~$100-150 |
| Architectural asphalt | ~$150-250 |
| Metal | ~$300-600 |
| Tile / slate | ~$400-1,000+ |
How much does it cost to replace a roof? For an average home (roughly 20-25 squares), total roof replacement typically runs from $8,000 for basic asphalt shingles to $25,000+ for metal or premium materials, including labor.
How many shingles do I need for my roof? Divide your roof's actual surface area (footprint × pitch multiplier) by 100 to get the number of squares, then add about 10% extra for waste from cuts and overlaps.
What's a roofing 'square'? A square is a roofing industry unit equal to 100 square feet of roof surface — shingles, underlayment, and labor are all typically priced per square.
Does roof pitch really affect the cost that much? Yes — steeper roofs have more actual surface area for the same footprint, plus they're slower and more dangerous to work on, both of which increase material and labor costs.