Roof Replacement Cost Calculator

Roof replacement cost calculator for asphalt shingles. Prices tear off, disposal, deck repair, underlayment, ice barrier, shingles and labor by pitch and story.

By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.

Quick answer: To price a roof replacement, work in squares: strip and haul the old roof, replace the soft sheathing, then price underlayment, ice barrier, edges, shingles and labor with a pitch and height multiplier. A 40 x 30 ft house with a 6 in 12 roof and architectural shingles runs about $8,700 to $16,300, or $581 to $1,082 per square.

Your measurements

Gable end: pitch is the rise over a 12 in run; the factor from that pitch turns footprint into roof area.

House lengthftMeasured at the ground along the ridge direction, wall to wall. The overhang is added separately.House widthftWall to wall across the gable end. A 40 x 30 ft footprint is a 1,200 sq ft single story house.Eave and rake overhangftHow far the roof extends past the wall. Most houses run 12 to 24 in, and it adds real area on all four sides.Roof pitchPitch adds area and adds labor twice over. Past 8 in 12 a crew needs staging and roof jacks, which is where the premium comes from.Roof shapeValleys, dormers and hips drive both waste and labor. A cut up roof costs more per square than a plain gable of the same area.HeightHeight changes the setup, the fall protection and how far every bundle and every piece of debris has to travel.Existing layers to tear offIRC R908.3 bars a recover over two or more existing applications. Enter 0 only if the deck is already bare.Deck sheathing to replace%Share of the 4x8 sheets that come up soft. Budget 10% sight unseen; a roof that has leaked at a valley or around a chimney runs higher and is only known once the shingles are off.Shingle gradeArchitectural shingles are the default on almost every reroof now. Impact rated designer shingles can earn a homeowners insurance discount in hail country.Ice barrier at the eavesIRC R905.1.2 requires an ice barrier from the eave edge to 24 in inside the exterior wall line wherever there is a history of ice forming along the eaves.

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Replacement cost range$8,700 to $16,300All results

Results

Replacement cost range: $8,700 to $16,300; 1,503 sq ft of roof at 6/12 on a 1 story house, architectural shingles, 1 layer torn off
Cost per square: $581 to $1,082 per square; A square is 100 sq ft of roof. Roofers quote this way, so it is the number to compare bids against
Roof area: 15 squares; 1,503 sq ft, from a 1,344 sq ft footprint times the 1.118 pitch factor. Order 17.3 squares with 15% waste
Tear off and disposal: $1,653 to $2,855; 1 layer stripped and hauled. A square of asphalt shingles weighs 250 to 400 lb, so this roof makes 2.4 tons of debris
Deck repair: 5 sheets, $350 to $600; 10% of the sheathing at $70 to $120 a sheet installed. This is the line that moves after the shingles come off
Shingles: $2,246 to $3,456; 17.3 squares of architectural, 30 to 50 year at $130 to $200 a square, material only
Underlayment and ice barrier: $804 to $1,557; 2 courses of ice barrier covering 504 sq ft, then synthetic underlayment over the rest
Edges and ridge: $683 to $1,408; 156 ft of drip edge, 84 ft of starter and 42 ft of ridge cap
Installation labor: $2,592 to $5,184; 15 squares at $150 to $300 a square, times 1.15 for the 6/12 pitch, 1 story height and moderate shape
Labor share of the low end: 53%; Tear off, disposal, deck repair and installation. Materials are the smaller half of a reroof, which is why bids vary so much
Planning estimate only: Get three local quotes; Labor rates, disposal fees and what the deck looks like under the old roof move this more than any input here

Roof Replacement Cost formula

Roof area = (Length + 2 x Overhang) x (Width + 2 x Overhang) x Pitch factor
Pitch factor = square root of (1 + (Rise / 12) squared)
Squares = Roof area / 100, ordered with 10 to 22% waste depending on how cut up the roof is
Tear off = Squares x $75 to $125 per layer, plus $35 to $65 a square for disposal
Labor = Squares x $150 to $300 x Pitch multiplier x Story multiplier x Shape multiplier

Worked example

A 50 x 36 ft two story house with a 10 in 12 roof, a cut up shape with several dormers, two existing layers, 20 percent of the sheathing bad and designer impact rated shingles.

The footprint with a 1 ft overhang is 1,976 sq ft, and the 10 in 12 pitch factor of 1.302 takes the roof to 2,572 sq ft, or 25.7 squares. Two layers to strip and haul cost $6,122 to $10,546 on their own. The labor multiplier compounds to 2.27 once the steep pitch, the second story and the cut up shape are stacked, so installation alone runs $8,751 to $17,501. The roof lands near $26,400 to $49,600, or $1,026 to $1,927 a square. That is nearly double the per square figure of the simple example, on a roof only 71 percent larger.

Quick reference

Typical 2026 US line items for an asphalt shingle reroof
Line item	Basis	Typical range
Tear off labor	Per square per layer	$75 to $125
Disposal and dumpster	Per square per layer	$35 to $65
Deck sheathing replacement	Per 4x8 sheet installed	$70 to $120
Ice barrier membrane	Per sq ft covered	$1.00 to $1.90
Synthetic underlayment	Per sq ft	$0.30 to $0.60
Drip edge	Per linear foot	$2.50 to $5.00
Starter strip	Per linear foot of eave	$1.50 to $3.00
Ridge cap	Per linear foot of ridge	$4 to $9
3 tab shingles	Per square, material	$105 to $145
Architectural shingles	Per square, material	$130 to $200
Designer or impact rated	Per square, material	$250 to $450
Installation labor	Per square, before multipliers	$150 to $300

Everything is priced by the square, and the square is not the footprint

Roofers work in squares of 100 square feet, and every line on a bid is a rate per square. The trap is that the roof is always bigger than the house under it. Multiply the footprint, overhangs included, by the pitch factor: a 6 in 12 roof is 12 percent larger than the plan area, an 8 in 12 is 20 percent larger and a 12 in 12 is 41 percent larger. Pricing a steep roof off the floor area understates it badly.

Pitch then charges a second time, in labor. Up to 6 in 12 a crew walks the roof. Past 8 in 12 they need roof jacks and staging, and the labor rate climbs 25 to 50 percent. A second story adds another 12 percent and a third around 28, because every bundle and every piece of debris travels further. Those multipliers compound, which is why a steep cut up roof on a tall house can cost double per square what a plain ranch gable costs.

The deck is the line nobody can quote honestly up front

What is under the old shingles is unknown until they come off. A reasonable bid names a rate per sheet for replacement, typically $70 to $120 installed, and an allowance of about 10 percent. A roof that has leaked at a valley, a chimney or a skylight will run well past that, and the honest way to handle it is a unit price in the contract rather than a number pulled on the day.

Two related items get skipped and both are code. IRC R905.1.2 requires an ice barrier from the eave edge to 24 inches inside the exterior wall line anywhere ice forms at the eaves, which on a steep roof with a deep overhang means two courses of membrane, not one. IRC R905.2.8.5 requires drip edge at eaves and rakes. Neither is expensive, and both are what stops water reaching the fascia and the ceiling.

What this calculator leaves out

Anything that is not a straightforward asphalt shingle reroof. It does not price metal, tile, slate or cedar, low slope sections that need a membrane, or a roof that has to be framed or re-sheathed wholesale. Skylights, chimney rebuilds and cricket flashing, new gutters and downspouts, ridge or soffit ventilation added or corrected, solar panel removal and reinstallation, insulation and interior repair from an existing leak, and asbestos containing roofing that needs abatement all sit outside it. Structural repair where the rafters or trusses have sagged needs an engineer, not a roofer's square rate.

Code limits that apply

IRC R908.3
No new roof covering over two or more existing applications of any type
If you miss it: A third layer has to come off at the next reroof, and the inspector can reject the recover outright
IRC R905.1.2
Ice barrier from the eave edge to 24 in inside the exterior wall line where ice forms at eaves
If you miss it: An ice dam backs water under the shingles and into the ceiling below, which is interior damage
IRC R905.2.2
Asphalt shingles only on slopes of 2 in 12 or more, and double underlayment from 2 to under 4 in 12
If you miss it: Shingles on a shallower slope leak under wind driven rain and void the manufacturer warranty
IRC R905.2.8.5
Drip edge at eaves and rakes, 2 in flange, extending 0.25 in below the sheathing, laps 2 in
If you miss it: Without drip edge the water runs back onto the fascia and rots it behind the gutter
IRC R908.3.1.1
No recover where the existing roof is water soaked or has deteriorated to where it is not a base
If you miss it: New shingles over a soft deck telegraph every bad sheet and pull their fasteners loose
IRC R106.1
A reroof needs a permit and an inspection in nearly every jurisdiction
If you miss it: Unpermitted roof work surfaces at sale and can be excluded from an insurance claim

Provision	Limit	If you miss it
IRC R908.3	No new roof covering over two or more existing applications of any type	A third layer has to come off at the next reroof, and the inspector can reject the recover outright
IRC R905.1.2	Ice barrier from the eave edge to 24 in inside the exterior wall line where ice forms at eaves	An ice dam backs water under the shingles and into the ceiling below, which is interior damage
IRC R905.2.2	Asphalt shingles only on slopes of 2 in 12 or more, and double underlayment from 2 to under 4 in 12	Shingles on a shallower slope leak under wind driven rain and void the manufacturer warranty
IRC R905.2.8.5	Drip edge at eaves and rakes, 2 in flange, extending 0.25 in below the sheathing, laps 2 in	Without drip edge the water runs back onto the fascia and rots it behind the gutter
IRC R908.3.1.1	No recover where the existing roof is water soaked or has deteriorated to where it is not a base	New shingles over a soft deck telegraph every bad sheet and pull their fasteners loose
IRC R106.1	A reroof needs a permit and an inspection in nearly every jurisdiction	Unpermitted roof work surfaces at sale and can be excluded from an insurance claim

Rows marked checked produce a warning in the results when an entry crosses the limit. The others are on the plans or on site and this calculator does not test them. Local amendments can be stricter; the adopted edition and the inspector govern.

Mistakes that cost money

Pricing from the footprint instead of the roof area. A 6 in 12 roof is 12 percent larger than the floor below it, and a 12 in 12 is 41 percent larger.
Taking a bid that says nothing about deck replacement. Bad sheathing is found after the shingles are off, so the rate per sheet belongs in the contract.
Roofing over a second layer. IRC R908.3 bars it, the assembly holds heat, and the next roofer has to strip all three.
Leaving out the ice barrier in a cold climate to save a few hundred dollars. Ice dams back water up under the shingles, and that damage is interior.
Reusing old drip edge or skipping it. IRC R905.2.8.5 requires drip edge at eaves and rakes, and it is what keeps water off the fascia.
Comparing bids without the waste factor. A cut up roof needs 20 percent or more, and a bid priced at 10 percent will come back for a change order.

Key facts

Replacing an asphalt shingle roof on a 40 by 30 ft house with a 6 in 12 pitch typically costs $8,700 to $16,300, which is $581 to $1,082 per square.
A roofing square is 100 square feet, and a square of asphalt shingles weighs 250 to 400 lb, so a 15 square roof makes about 2.4 tons of tear off debris.
IRC R908.3 does not allow a new roof covering to be installed over two or more existing applications, so a second recover means a full tear off.
IRC R905.1.2 requires an ice barrier from the eave edge to at least 24 in inside the exterior wall line wherever ice has formed along the eaves.
Labor, tear off and disposal are just over half a reroof bill on a simple roof and about two thirds on a steep cut up one, which is why two quotes on the same materials differ by thousands.
A 10 in 12 pitch adds 30 percent to the roof area over a flat footprint and about 50 percent to the labor rate, because the crew needs staging and roof jacks.

Frequently asked questions

How much does it cost to replace a roof?

A 40 by 30 ft house with a 6 in 12 roof and architectural shingles typically runs $8,700 to $16,300, which is $581 to $1,082 per square. Steep, tall or cut up roofs run well past that on the same area.

How much is a roofing square?

A square is 100 square feet of roof surface. Installed, an asphalt shingle roof typically runs $550 to $1,100 a square all in, with the shingles themselves only $105 to $450 of that.

Can I put a new roof over the old shingles?

Only over a single existing layer. IRC R908.3 does not allow a recover over two or more applications, or over a deck that is water soaked or deteriorated. A recover also hides bad sheathing and shortens the new roof's life.

Why are roof replacement quotes so different?

Labor, tear off and disposal are over half the bill, and those are the parts that vary by crew and by how the roof is accessed. Check that every bid uses the same waste factor, the same deck allowance and the same underlayment.

Sources and references

Chapter 9 Roof Assemblies, underlayment, ice barrier, drip edge and reroofing, 2021 IRC (ICC)
Technical bulletins on asphalt shingle application and ventilation (Asphalt Roofing Manufacturers Association)
Technical resources for low slope and steep slope roof systems (National Roofing Contractors Association)

Next steps for this project

The usual order for a roofing & siding project. See all roofing & siding calculators.

Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.