Estimate your roof replacement cost
Your roof is bigger than your house
This trips up most cost estimates. Roof area is always larger than your home's footprint because of the slope, and the steeper the roof, the bigger the gap. Multiply your footprint by the pitch multiplier to get true roof surface — that's the number contractors actually price against.
| Pitch | Area multiplier | Extra labor premium |
|---|---|---|
| Low (about 4/12) | ×1.054 | 0% |
| Moderate (about 6/12) | ×1.118 | 0% |
| Steep (about 8/12) | ×1.202 | 25% |
| Very steep (12/12+) | ×1.414 | 40% |
These are two separate effects that both push the price up: a steeper roof has more surface to cover and costs more per square foot to work on, because of safety equipment and slower installation. The 12/12 area multiplier is derived from the same geometric formula as the published ones — see sources.
Roof replacement cost by material
| Material | Per sq ft installed | Typical lifespan |
|---|---|---|
| Asphalt — 3-tab | $4.50–$7.50 | 20–25 years |
| Asphalt — architectural | $4.50–$10 | 25–30 years |
| Metal — standing seam | $8–$18 | 40–70 years |
| Concrete/clay tile | $10–$18 | 50+ years |
| Wood shake | $9–$14 | 25–30 years |
| Slate | $15–$30 | 50–100+ years |
One roofing square = 100 square feet. Most homes need 15–30 squares. Labor is the larger half of a roofing bill — roughly 55% of the total for a typical job — which is why regional wage differences move the price so much.
Tear-off: already in the price, with two exceptions
Quoted installed prices per square foot normally already include stripping one layer of old shingles, disposal and the permit. That's how contractors price a replacement, and it's why our calculator doesn't add a separate tear-off charge for a single layer. Two situations change the number:
- Two old layers: removing a second layer adds about $0.40–$1.20 per square foot of roof surface.
- Overlay (no tear-off): installing over one existing layer costs roughly 22% less, because there's no removal or disposal.
Building codes generally allow one overlay over a single existing layer, and only if the deck is sound. Most roofing professionals still recommend full tear-off: an overlay hides decking problems, adds weight, and can void the new shingle warranty. Tear-off is also the only time anyone actually inspects your decking.
Decking repair — the most common budget surprise
Rotted plywood under the shingles has to be replaced before the new roof goes on, and nobody knows how much until the old roof comes off. Budget $2–$4 per square foot for the affected area. As a planning rule, older roofs need more: a roof under 25 years typically needs around 5% of decking replaced, 25–40 years around 15%, and over 40 years can reach 25% or more. Ask your contractor to photograph any rotten area before replacing it so you can verify what you're paying for.
Additional costs to expect
| Item | Typical cost | When it's needed |
|---|---|---|
| Permit | $150–$500 | Required for re-roofing in most jurisdictions |
| Chimney flashing | $200–$600 | Many quotes assume reusing old flashing — ask |
| Skylight/valley re-flashing | $300–$1,000 | Skylights, valleys, complex intersections |
| Isolated decking sheet | $100–$300 | Small localized rot, priced per sheet |
Questions to ask before you hire
- Is this quote based on measured roof surface area, or my home's square footage?
- Is tear-off included, and for how many existing layers?
- What's the decking allowance, and what's the per-sheet price if more is needed?
- Does the quote include new flashing, or does it assume reusing the old?
- Is the permit included?
- What's the workmanship warranty, separate from the manufacturer's material warranty?
Methodology and sources
We build each estimate from its parts: an installed per-square-foot price by material, split into material and labor portions, with the labor portion adjusted for your state's roofer wages and your roof's pitch. Tear-off, decking and add-ons are priced separately. Read how we estimate costs.
- Modernize: roof replacement cost calculator — per-material installed pricing, labor/material split
- BuildVision: roof replacement cost — pitch multipliers, labor share, regional variance
- SubcontractorHub: roof replacement cost breakdown — per-material cross-check
- ShinglesCalculator: tear-off cost — tear-off by layer count, permit range
- RoofPitch.net: roof replacement calculator — decking and flashing pricing
- U.S. Bureau of Labor Statistics: OEWS May 2025, State (SOC 47-2181, Roofers) — state labor index
The labor share, pitch labor premiums and the derived 12/12 area multiplier have not yet been reviewed by a licensed roofing contractor.
Changelog
- : Initial dataset. This is the hardest page in Wave 1 (KD 30, real competition from NerdWallet/Angi), so every figure carries at least one source and most carry two independent ones. Installed $/sq-ft by material from Modernize, SubcontractorHub and BuildVision, which converge closely. Labor share (55%) is the midpoint of BuildVision's stated 50-60% and cross-checks against Modernize's own materials-vs-labor split on a sample job. Pitch multipliers are published geometric factors (1.054 at 4/12, 1.118 at 6/12, 1.202 at 8/12); the 12/12 value (1.414) is derived from the same sqrt(1+(rise/12)^2) formula those follow, flagged as derived. Pitch labor premiums are separate from the area effect and come from three sources. Tear-off and decking rates cross-check across ShinglesCalculator, RoofingCalculatorHQ, RoofPitch and BuildVision. State wage index uses Roofers (SOC 47-2181) - the right trade for this page - pulled from the BLS file already on hand; all 51 regions have data, and the computed IL figure matches BLS's separately published IL roofer median exactly. Status stays draft pending a licensed roofing contractor's review of the labor share, the pitch premiums and the derived 12/12 multiplier.
- : CORRECTION after benchmark review: tear-off was double-counted. Installed per-sq-ft prices already include removing one layer, disposal and permits (Empire Home Protect, Clean Roofing), but the calculator added a tear-off line on top. The default job (1,800 sq ft footprint, moderate pitch, architectural shingles) came out near $19,200 against independent benchmarks of roughly $8,000-$16,000 for a 2,000 sq ft home. Fixes: one-layer tear-off is now included ($0 extra); a second layer adds $0.40-$1.20/sq ft; overlay applies a 22% discount (source: 20-25% less). Moderate pitch no longer carries a labor premium, since installed prices assume a standard pitch. Architectural shingle typical price lowered from $7.50 to $6.75/sq ft to reflect four sources ($4.50-$8.00, $4.50-$8.00, $6-$9, $5.50-$10). The default job now estimates about $14,200, inside the benchmark range.
- : Editorial review and publication. Every price field re-checked for a source; the calculator's typical default job tested against independently published benchmark ranges (tests/benchmarks.test.ts), which now run on every build. Published at the owner's decision with an explicit note that the page has not yet been reviewed by a licensed tradesperson; the page must not claim such a review until one has actually happened.