Roof Replacement Cost Calculator
Replacing a roof? Enter your home's footprint and roof pitch to get the number of roofing squares needed, the material cost, and an estimated total installed price including labour.
Common sizes
Jump to a pre-filled estimate:
How it works
Roofers measure in “squares” — one square covers 100 sq ft of roof. We take your home's footprint (length × width), multiply by a pitch factor (a steeper roof has more surface than the footprint), add a waste allowance for cuts and ridge/hip caps, then convert to squares and price both material and labour per square.
The formula
Roof area = Length × Width × pitch factor. Squares = (roof area ÷ 100) × (1 + waste%). Installed cost = squares × (material price + labour price).
Worked examples
| Example | Result |
|---|---|
| 40×30 home, medium pitch | A typical single-storey home: about 15.5 squares, roughly $4,950 installed for asphalt shingles. |
| 50×40 home, steep pitch | A larger steep-roofed home: about 29 squares. |
| 30×25 bungalow, low pitch | A small low-slope roof: about 8.8 squares. |
Frequently asked questions
How many squares is my roof?
One roofing square equals 100 square feet of roof surface. A 1,200 sq ft footprint at a medium pitch works out to roughly 15–16 squares once pitch and waste are included.
How much does a new roof cost?
Asphalt shingle roofs typically run $4.50–$8.00 per square foot installed ($450–$800 per square). Metal, tile and slate cost considerably more. This tool separates material from labour so you can localise both.
Does roof pitch affect cost?
Yes — a steeper roof has more surface area than its footprint and is slower and riskier to work on, so both material and labour rise. Pick the closest pitch band above and the estimate adjusts automatically.
Should I include a waste allowance?
Yes — 10–15% is standard to cover cuts, starter and ridge/hip caps, and valleys. Complex roofs with many hips and valleys sit at the higher end.
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Method reviewed by The editorial team. See our methodology for sources and assumptions.