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Roof Replacement Cost Estimator

Cost to replace a roof by material, pitch and number of old layers to tear off.

sq ft

Results update as you type. The maths runs entirely in your browser — nothing you type is sent anywhere.

Before you order: get three written quotes on identical scope. The spread between the cheapest and dearest bid on the same job is routinely 30%, and it costs nothing to ask.

Roofing quotes vary wildly for the same house, and pitch is the reason more often than material. A walkable 3:12 roof can be stripped and shingled by two people in a day; a 9:12 roof with valleys and three dormers needs staging, harnesses and twice the labour hours for the same shingle count.

Note that roof area is always larger than the footprint you measure on the ground. Pitch multiplies it — a medium 6:12 pitch adds about 28%, and a steep roof can add 50% or more. Quoting off the footprint alone is how homeowners end up 30% over budget.

How this calculator works

Every field is editable and the result updates as you type — nothing is submitted anywhere, all the maths runs in your browser. That matters for a number you are about to spend money on: you can see exactly which input moved the answer, and by how much.

What this calculation assumes

Assumes a simple gable roof with no dormers, skylights or complex valleys. Second-storey access, pitches above 9:12, and historic-district or HOA material requirements all add labour on top of these rates.

Treat the result as an order-of-magnitude check rather than a final quantity. Product packaging changes, regional labour rates vary by a factor of two, and no calculator has seen your actual site.

Frequently asked questions

Should I tear off the old roof or shingle over it?

Tear off in almost every case. Going over old shingles is cheaper upfront but traps moisture, hides rotten decking, voids most manufacturer warranties on the new layer, and often violates code once there are already two layers up.

How often does a roof need replacing?

Asphalt shingles last 20 to 25 years, standing seam metal 40 to 70, clay tile 50 or more. Actual life depends far more on attic ventilation than on the material spec — a poorly vented roof can fail asphalt in 12 years.

When is the cheapest time to replace a roof?

Late autumn and winter in most of the US, when roofing crews are slow and will negotiate. Avoid hurricane season if you are in a coastal state — both price and lead time spike right after a storm event.

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