How much does it cost to replace a roof?

There is no single honest answer, and this page does not publish one of its own. What it does is take somebody else's published, bylined, dated range and scale it onto your actual roof area. This Old House gives $8,419 to $11,665 for asphalt shingles on a 2,000 sq ft roof, updated 12 March 2026. On a 1,575 sq ft roof that scales to $6,630 to $9,186 before tear-off. Treat it as a ranking with a plausible spread rather than a quote.

Is roof cost per square foot of house or of roof?

Of roof, always, and that is the mistake this page exists to catch. Your roof is bigger than your house by the eave overhang on all four sides and then again by the slope factor for your pitch. A 40 by 28 house at 6:12 with a two-foot eave has 1,575 sq ft of roof over a 1,120 sq ft footprint, 40.6% more. Publishers are not always careful about the distinction: This Old House attaches the identical range of $6,885 to $23,993 to a “2,000-square-foot house” on one page and a “2,000-Square-Foot Roof” on another.

How many squares is my roof?

A square is 100 sq ft, so it is your roof area divided by 100. Get the roof area by adding the overhang to both dimensions of your footprint, multiplying those out, then multiplying by the slope factor for your pitch. The 40 by 28 example is 15.75 squares. The roofing calculator on this site turns that into bundles, fasteners and underlayment.

Does a published roof replacement average include tear-off?

Usually it is not stated, which is why this page keeps it as a separate line. This Old House prices removal of the old roof at $1 to $5 per square foot of old material. On 1,575 sq ft that is $1,575 to $7,875, a five-fold spread, and it is wider in absolute dollars than the spread on the shingles themselves.

Why is the average roof cost so much higher than the table on the same page?

Because it is not an average. This Old House's new roof guide states $15,439 on average against a range of $6,885 to $23,993. Those two endpoints sum to $30,878, and half of that is $15,439 exactly, so the headline is the midpoint of a range rather than a mean of anything. The same page's material table puts asphalt at $10,042 for a 2,000 sq ft roof, about 54% lower. The tables are the more useful half of the page.

Does a steep roof cost more?

Yes, and none of the published figures here carry it. Above roughly 8:12 a roof cannot be walked, so the work needs staging and fall protection and takes longer. The source states its table describes low-sloped roofs, so applying it to a 10:12 is using a number outside what it was built for. This page warns you when your pitch leaves that range rather than applying a multiplier it cannot source.

Why does this calculator not just give me one number?

Because the number would be invented. Every figure of money on this page belongs to a named publisher with a publication date, and the page shows the arithmetic that scales it onto your roof. The part this site actually contributes is the 1,575, and that part is exact.

Home › Roofing › Roof Replacement Cost Calculator

Roof Replacement Cost Calculator

Areas from the slope factor, prices quoted from a dated third party

A roof price quoted per square foot is per square foot of roof. The number most people type into a cost calculator is the house, and on an ordinary gable those are not the same number.

Roof replacement estimate

Building length

Building width

Pitch, rise per 12

Eave overhang (from the wall line)

Roof covering (as the source lists them)

Tear off the old roof (rather than overlay)

Areas are computed from your footprint, pitch and overhang. The money is somebody else's published range, scaled by area and attributed below. This site publishes no price of its own.

Specification summary

Generated from on . Reopen that address to reproduce these figures exactly.

Entered

Result

What you measured, and what you are buying

Worked example

A 40 ft by 28 ft house at 6:12 with a 24 in overhang, reroofed in plain asphalt shingles with the old roof torn off.

The footprint is 1,120 sq ft, and that is the number people type in. Forty by twenty-eight. It is also the number that appears in a sentence like “a 2,000-square-foot house”, which is where the trouble starts.
The overhang is roof. Two feet on all four sides makes the plan area 44 ft by 32 ft, or 1,408 sq ft, before any pitch is considered at all. That is 26% more than the footprint and it has not left the ground yet.
The pitch multiplies what is left. At 6:12 the slope factor is √(144+36)/12 = 1.1180, so 1,408 becomes 1,575 sq ft of roof. Against the 1,120 sq ft footprint that is 40.6% more area.
The published range is for a 2,000 sq ft roof, so it scales. This Old House gives $8,419 to $11,665 for asphalt on a 2,000 sq ft roof. Times 1,575/2,000 that is $6,630 to $9,186.
Pricing the footprint instead would have said $4,715 at the low end. The same source, the same material, the same house, $1,915 short, because the estimate was sized on the wrong rectangle.
Tear-off is separate and it is not small. At the source's $1 to $5 per square foot of old material, 1,575 sq ft is $1,575 to $7,875, which takes the whole job to $8,205 to $17,061. The spread on the tear-off alone is wider than the spread on the shingles.

The useful output is not the total, it is the 1,575. Every roofing quote you collect will be priced against a roof area, and if yours and theirs disagree you have found the thing worth arguing about before you have found the price.

The formula

Two multiplications to get the area, then one division to scale somebody else's published figure onto it:

cost = published range × (footprint_plan × √(144 + rise²)/12) / 2,000

published range: the source's low and high for the 2,000 sq ft roof it states, quoted and dated, not ours
footprint_plan: (L + 2 × overhang) × (W + 2 × overhang), which is bigger than L × W
√(144 + rise²)/12: the slope factor, exact trigonometry, never a table
2,000: the roof size the source's figures are stated for, so the division is undoing their basis rather than inventing a rate

The division is the honest part. A per-square-foot rate could have been derived once and printed, but then the page would be quoting a number the source never published. Dividing their stated total by their stated area, in front of you, is the same arithmetic with the working left in.

Four different answers, one publisher, one week

This Old House is the source used here because it carries a byline and a date, which most roofing cost pages do not. It is also, read carefully, four different answers to the same question, and the differences are instructive rather than disqualifying.

The headline is a midpoint, not an average. The new roof guide opens with “A new roof costs $15,439 on average, with most homeowners paying between $6,885 and $23,993.” Add those two endpoints and halve them: 30,878 / 2 = 15,439, exactly. That is the middle of a stated range, which is a different thing from an average, and it is about 54% above the $10,042 that the same page's own material table gives for asphalt on a 2,000 sq ft roof.

The same two numbers describe a house on one page and a roof on another. The shingle guide says $6,885 to $23,993 “for a 2,000-square-foot house”. The new roof guide's table is headed “Average Cost for a 2,000-Square-Foot Roof”. Those are not the same building, and the gap between them is the whole subject of this page.

The size tables are a straight line, and you can see the model. The metal column runs 18,739 / 28,012 / 37,285 / 46,558 / 55,831 for 1,000 to 3,000 sq ft. Every step is exactly 9,273, four times in a row, which makes it $193 plus $18.546 per square foot. That reproduces all five rows to the dollar. It is a formula, not a survey.

So the “cost per square foot” column is total divided by 2,000, not the slope of the table. Metal is listed at $18.64, which is 37,285/2,000. Use that rate on a 1,000 sq ft roof and you get $18,640 against the table's own $18,739. Use it on 3,000 and you get $55,920 against $55,831. It only agrees with the table at exactly 2,000 sq ft, which is the one size it was derived from.

None of that makes the figures useless. It makes them a ranking with a plausible spread, which is what this page uses them as, and it is why the page scales the source's stated total by area rather than adopting the per-square-foot column as a rate.

Published roof replacement prices, and the four different answers in them

Not this site's numbers. This Old House, shingle roof cost, Written by Stephanie Minasian-Koncewicz, published 12 March 2026 and read here on 2026-09-09.

As published by This Old House, shingle roof cost, installed, for a 2,000 sq ft ROOF, not a 2,000 sq ft house
Item	Low	High	Unit
Asphalt shingles	$8,419	$11,665	2,000 sq ft roof
Architectural asphalt shingles	$11,914	$16,436	2,000 sq ft roof
Composite shingles	$13,420	$17,679	2,000 sq ft roof
Fiberglass shingles	$16,259	$21,727	2,000 sq ft roof
Cedar shingles	$21,519	$29,232	2,000 sq ft roof
Steel shingles	$21,519	$29,232	2,000 sq ft roof
Synthetic slate shingles	$21,595	$30,304	2,000 sq ft roof
Tear-off of the old roof	$1	$5	per sq ft of old material

Source: This Old House, shingle roof cost, published 12 March 2026, read 2026-09-09. Two things to know before using these. First, the source states the table is for builder-grade materials, medium labor costs and LOW-SLOPED roofs, so a steep or cut-up roof is outside what it was built to describe. Second, cedar shingles and steel shingles carry identical figures, 21,519 to 29,232, which is not what a survey of two unrelated materials produces. Read the table as a ranking with a plausible spread, not as quotes.

This site publishes no price of its own. Why, and what that means for these figures.

Why the footprint is the wrong rectangle, twice over

Two separate things make a roof bigger than the house under it, and a cost page that asks for square footage collects neither.

The overhang comes first and it is pure plan area. A 24 in eave adds two feet to every side, so a 40 ft by 28 ft house has a 44 ft by 32 ft plan. That is 1,408 sq ft against 1,120, a 26% increase, and no pitch has been applied yet. On a small building it is proportionally worse: the same two-foot eave on a 24 ft by 20 ft garage takes 480 sq ft to 672, up 40%.

The pitch multiplies whatever the plan area turned out to be. The slope factor is √(144 + rise²)/12, and it is exact. At 4:12 it is 1.0541, at 6:12 it is 1.1180, at 12:12 it is 1.4142. So a steep roof on a small house can easily be half as much material again as the footprint suggests.

The two compound. Forty by twenty-eight at 6:12 with a two-foot eave is 40.6% more roof than house. Priced at the source's low asphalt figure that is the difference between $4,715 and $6,630 on one ordinary suburban roof, and the smaller number is the one a footprint-based calculator hands you.

The roofing calculator takes the same three inputs and turns them into squares, bundles, fasteners and underlayment. If you do not know your pitch, the roof pitch calculator gets it from a measurement you can take without going up.

What a published range cannot know about your roof

The figures on this page scale linearly with area, because the source publishes one size and linear is the only defensible thing to do with one point. Real roofing does not work that way, and the gaps run in both directions.

There is a fixed cost and it does not care how big your roof is. Mobilisation, the dumpster, the permit, the crew's day. The source's own table implies about $193 of it, which is far too little to be a real setup cost and is better read as an artifact of whatever model generated the table. Whatever the true figure, it means a 600 sq ft garage costs more per square foot than a 3,000 sq ft house, and scaling from a 2,000 sq ft basis understates the small job.

Steepness is not in these numbers at all. The source states its table is built on “low-sloped roofs”. Above roughly 8:12 a crew cannot walk the roof, which means staging, harnesses and a slower day. That is a labour multiplier and this page does not apply one, because inventing a multiplier would be making up a number. What it does instead is warn you when your pitch has left the range the source described.

Complexity is not in them either. Hips, valleys, dormers, skylights, chimneys, a cricket behind a chimney, and the number of separate planes. Every one of those is cut waste and flashing labour, and a cut-up roof of the same area is a materially different job from a plain gable.

And the deck under the old roof is unknown until the tear-off. That is the single commonest reason a roofing job finishes above its estimate, and no calculator on any site can see it.

Reading a roofing quote against this

The comparison worth making is not your total against the contractor's total. It is the three numbers underneath.

Their roof area against yours. Ask what area they measured. If a quote is priced on a number close to your footprint rather than your roof area, either they measured from an aerial and you should ask which, or the quote is going to grow. Getting agreement on the square footage is worth more than getting agreement on the price, because everything else is derived from it.

Tear-off as its own line. At $1 to $5 per square foot of old material this is a five-fold range on a real fraction of the job, and it moves with the number of existing layers, disposal fees where you live, and whether the deck needs repair. A quote that folds it into a single figure has hidden the most variable part.

What is included beyond shingles. Underlayment, ice barrier where your jurisdiction requires it, drip edge, valley metal, ridge vent, flashing at every wall and chimney, and pipe boots. Two quotes can differ by thousands on the same roof because one of them renews the flashing and the other reuses it.

And the pitch, if it is steep. If your roof is over about 8:12, a quote that matches a low-slope published range is either optimistic or is about to discover something.

Frequently asked questions

How much does it cost to replace a roof?: There is no single honest answer, and this page does not publish one of its own. What it does is take somebody else's published, bylined, dated range and scale it onto your actual roof area. This Old House gives $8,419 to $11,665 for asphalt shingles on a 2,000 sq ft roof, updated 12 March 2026. On a 1,575 sq ft roof that scales to $6,630 to $9,186 before tear-off. Treat it as a ranking with a plausible spread rather than a quote.
Is roof cost per square foot of house or of roof?: Of roof, always, and that is the mistake this page exists to catch. Your roof is bigger than your house by the eave overhang on all four sides and then again by the slope factor for your pitch. A 40 by 28 house at 6:12 with a two-foot eave has 1,575 sq ft of roof over a 1,120 sq ft footprint, 40.6% more. Publishers are not always careful about the distinction: This Old House attaches the identical range of $6,885 to $23,993 to a “2,000-square-foot house” on one page and a “2,000-Square-Foot Roof” on another.
How many squares is my roof?: A square is 100 sq ft, so it is your roof area divided by 100. Get the roof area by adding the overhang to both dimensions of your footprint, multiplying those out, then multiplying by the slope factor for your pitch. The 40 by 28 example is 15.75 squares. The roofing calculator on this site turns that into bundles, fasteners and underlayment.
Does a published roof replacement average include tear-off?: Usually it is not stated, which is why this page keeps it as a separate line. This Old House prices removal of the old roof at $1 to $5 per square foot of old material. On 1,575 sq ft that is $1,575 to $7,875, a five-fold spread, and it is wider in absolute dollars than the spread on the shingles themselves.
Why is the average roof cost so much higher than the table on the same page?: Because it is not an average. This Old House's new roof guide states $15,439 on average against a range of $6,885 to $23,993. Those two endpoints sum to $30,878, and half of that is $15,439 exactly, so the headline is the midpoint of a range rather than a mean of anything. The same page's material table puts asphalt at $10,042 for a 2,000 sq ft roof, about 54% lower. The tables are the more useful half of the page.
Does a steep roof cost more?: Yes, and none of the published figures here carry it. Above roughly 8:12 a roof cannot be walked, so the work needs staging and fall protection and takes longer. The source states its table describes low-sloped roofs, so applying it to a 10:12 is using a number outside what it was built for. This page warns you when your pitch leaves that range rather than applying a multiplier it cannot source.
Why does this calculator not just give me one number?: Because the number would be invented. Every figure of money on this page belongs to a named publisher with a publication date, and the page shows the arithmetic that scales it onto your roof. The part this site actually contributes is the 1,575, and that part is exact.

Check these numbers yourself

This Old House, shingle roof costWritten by Stephanie Minasian-Koncewicz, last updated 12 March 2026, read 2026-09-09. Source of the seven material ranges scaled by this page and of the $1 to $5 per sq ft tear-off figure. The source states the table describes builder-grade materials, medium labour costs and low-sloped roofs.
This Old House, new roof cost guideWritten by Stephanie Minasian-Koncewicz, updated 5 June 2026, read 2026-09-09. Not used for any figure on this page. It is the source of the $15,439 headline, the $6,885 to $23,993 range and the size tables discussed above, and it is cited so the arithmetic in that discussion can be checked.
2018 Seattle Residential Code, Chapter 9 Roof AssembliesSeattle Department of Construction and Inspections. Prints IRC Chapter 9 in full, including R905.2.2, which is the double underlayment requirement this page flags between 2:12 and 4:12. Used because codes.iccsafe.org returns HTTP 403.

How every figure here is verified: Sources & Method. Who builds this: About. Found something wrong? Tell us and it gets fixed or removed.

Figures on this page last checked against the source documents on 2026-09-09. Codes are amended locally; confirm against the edition your jurisdiction enforces.

Related calculators

No figure of money on this page is this site's own. The ranges belong to This Old House, are reproduced with the byline and date they carry, and are scaled by area with the arithmetic shown. They describe builder-grade work on low-sloped roofs by the source's own statement, they carry no allowance for pitch, roof complexity, deck repair or regional labour, and they were a model rather than a survey. The roof areas are this site's arithmetic and are exact; the money is somebody else's estimate and is not.