What will a new roof actually cost? This free roofing cost calculator converts your roof area into roofing squares and estimates total material cost, waste included.
A “roofing square” equals 100 sq ft. Price per square varies significantly by material – asphalt shingles are typically cheapest.
This estimates materials only. Labor, tear-off of old roofing, and structural repairs are separate costs not included here.
How the Roofing Cost Calculator Works
The Roofing Cost Calculator converts your raw roof area into “roofing squares” — the unit roofers actually price and order by — after adding a waste allowance for cuts, overlaps, and ridge/valley losses, then multiplies by your price per square for a total material cost estimate.
Formula: Area with waste = Roof area × (1 + Waste allowance ÷ 100). Squares needed = Area with waste ÷ 100 (since 1 roofing square = 100 sq ft). Estimated cost = Squares needed × Price per square.
- Roof area — the total roof surface area to be covered, in square feet
- Price per square — the dollar cost of materials for one roofing square (100 sq ft); varies significantly by material type
- Waste allowance — the percentage added for cuts, overlaps, and irregular roof features like valleys and hips
Example Scenarios
| Roof area (sq ft) | Waste allowance | Price per square | Squares needed | Estimated cost |
|---|---|---|---|---|
| 2,000 | 10% | $425 | 22.0 | $9,350 |
| 1,500 | 15% | $400 | 17.3 | $6,900 |
| 1,000 | 10% | $150 | 11.0 | $1,650 |
| 2,500 | 12% | $380 | 28.0 | $10,640 |
| 1,800 | 10% | $500 | 19.8 | $9,900 |
Roofing Cost Calculator FAQ
What counts as a “roofing square” and why do contractors use it?
A roofing square equals 100 square feet of roof surface. Roofers price materials — shingles, underlayment, flashing — by the square because it standardizes ordering across different roof sizes and shapes, so quotes and this calculator both use it as the base unit.What’s a reasonable waste allowance percentage to enter?
Simple roofs with few cuts often use closer to 10%, while roofs with many valleys, hips, dormers, or a steep pitch typically need 15% or more because there’s more cutting and material loss. When unsure, a contractor can estimate a waste percentage specific to your roof’s shape.Does this estimate include tear-off of the old roof?
No — this calculator estimates new material costs only. Removing and disposing of existing roofing, which often involves dumpster fees and additional labor, is a separate cost that isn’t factored into this total.Why do prices per square vary so much between roofing materials?
Asphalt shingles, metal panels, tile, and slate all have very different material and installation costs per square, and pricing also shifts with brand, warranty length, and regional labor rates. Enter the price quote specific to the material you’re considering for an accurate estimate.Is a structural inspection needed before re-roofing?
For most straightforward reroofs, no, but if there are signs of sagging, water damage, or you’re switching to a heavier material like tile, a licensed roofing contractor or structural professional should inspect the decking and framing first. This calculator only estimates surface material costs, not structural work.Does this calculator account for roof pitch or slope?
Not directly — you enter the actual roof surface area, which should already reflect the sloped surface (not just the footprint measured from the ground). If you only have the footprint area, a roofer can apply a pitch multiplier to convert it to true surface area before you use this calculator.Related Calculators
Thinking about adding solar alongside a re-roof? The solar panel calculator for estimating panel count against available roof space is worth checking before materials are ordered. If you need to nail down the exact roof or building footprint first, the square footage calculator for measuring irregular roof sections can help, and larger reroofing projects that involve foundation or driveway work may also want the concrete calculator for estimating bags needed for related concrete work.