Enter your home footprint and roof basics to get roofing squares and a realistic installed price range — tear-off, shingles, labor and the decking surprise broken out.
Updated September 2026 · Free · No sign-up
Estimate your roof replacement
Roof size
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Estimated installed cost
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Line item
Range
Decking rot can only be confirmed after tear-off. Get the per-sheet price in writing before you sign.
What drives roof replacement cost
Roofers price in squares — one square is 100 square feet of roof area — and your roof area comes from geometry, not your floor plan. After size, the biggest levers are:
Pitch and height: steep or two-story roofs need staging, harnesses and slower crew movement. A two-story colonial at 10/12 can exceed $900 per square.
Tear-off layers: each existing layer adds $80 to $150 per square in tear-off and disposal.
Decking condition: the wildcard. Rot hides until tear-off, and sheets run $90 to $150 each.
Material: standing seam metal runs $12 to $20 per square foot installed — 2 to 3 times shingles — with exposed-fastener steel at $7 to $12 as the budget path.
How the math works
We convert your footprint to roof area with standard pitch factors plus a 5% overhang allowance, then build the estimate from the same line items a professional quote should show: tear-off, shingle material, underlayment, labor, flashing and permit. Labor scales up with pitch and story count. The decking line uses the sheet count you budget — six is a typical allowance on an older roof.
Tip: quotes outside the $450 to $750 per square band usually have a story — brutal access, rotten decking, or a premium material. Ask which one, and get it itemized in writing.
An asphalt shingle roof on a typical single-family home runs $8,000 to $20,000 installed, with most mid-size jobs landing between $11,000 and $15,000. The number that matters is per square (100 sq ft of roof): architectural shingles run $450 to $750 per square installed with tear-off included.
How do I figure my roof size from my floor plan?
Multiply your home footprint by a pitch factor — about 1.05 at a 4/12 pitch, 1.12 at 6/12, 1.20 at 8/12 and 1.41 at 12/12 — then add roughly 5% for overhangs. An 1,800 sq ft ranch at 6/12 works out to about 21 squares, not 18.
Should I overlay new shingles instead of tearing off?
Usually not. An overlay saves $1,000 to $2,500 upfront, but the crew cannot inspect decking that stays buried, the trapped layer shortens shingle life, and most manufacturers limit warranty terms on second-layer installs. It only makes sense over a sound single layer on a house you are selling soon.
What is the decking surprise?
Nobody knows what the wood looks like until the shingles come off. Contractors quote decking per 4x8 sheet, typically $90 to $150 installed. On a 20-square roof, six bad sheets adds $540 to $900; long-running leaks can push past $2,000. Get the per-sheet price in writing before signing.
