How to measure a roof for a quote
You do not need to climb up. Measure the outside of the house from the ground, add the overhangs, and you have the footprint. A single-storey house is close to its floor area. A two-storey house is about half its floor area, plus any garage or porch roof, which is where most online estimates go wrong.
Then find the pitch, from the attic or from old paperwork. The pitch adds area you cannot see from the ground: a 6 in 12 roof has about 12 percent more roof than footprint, and a steep 12 in 12 roof about 41 percent more. The roof pitch calculator explains how to read it safely.
Count the old layers if you can, by looking at the edge of the roof at a gutter. Each extra layer means more labor and disposal. Note anything sagging or soft, since rotten decking is the most common cost that does not show up until the old roof is off.
A worked example
Here is a 1,200 square foot footprint at 6 in 12, in architectural asphalt, with one layer to tear off, at the baseline region. These lines come from the same formula the calculator above runs.
1,200 sq ft footprint, architectural asphalt, one layer off
- Roof area: 1200 × 1.118 = 1342 sq ft
- Squares: 13.4
- Material, installed: $6,000.00 to $16,800.00
- Tear-off: $1,300.00 to $2,000.00
- Total: $7,400.00 to $18,800.00, middle $13,100.00
That is a wide range, and it should be. Omni's figures imply $6,000 to $12,000 for a 30 square roof, Inch Calculator's $13,500 to $37,500, and Zonda's Cost vs. Value has one fully specified 30 square job with skylights at $31,871. That job is one defined scope and not a typical bill. For the shingle count itself, see the roofing calculator.
New roof cost by material
All for a 1,500 square foot footprint at 6 in 12 with one layer off, at the baseline region. The per square foot column is the installed price from the estimate, before tear-off, so you can compare it with a quote written that way.
| Material | Low | Middle | High | Per square foot |
|---|---|---|---|---|
| 3-tab asphalt | $8,800.00 | $12,600.00 | $16,400.00 | $4.25 to $8.25 |
| Architectural asphalt | $9,200.00 | $16,400.00 | $23,500.00 | $4.50 to $12.50 |
| Cedar or wood shake | $15,100.00 | $20,800.00 | $26,500.00 | $8.00 to $14.30 |
| Steel | $9,200.00 | $20,100.00 | $31,000.00 | $4.50 to $17.00 |
| Aluminum | $12,600.00 | $25,200.00 | $37,700.00 | $6.50 to $21.00 |
| Tile | $10,100.00 | $21,400.00 | $32,700.00 | $5.00 to $18.00 |
| Slate | $21,800.00 | $30,600.00 | $39,400.00 | $12.00 to $22.00 |
Mistakes that blow a roof budget
- Floor area as the footprint. A two-storey house has about half the roof you would think from its floor area. A sprawling ranch has more.
- No allowance for decking. Nobody can price rotten sheathing from the ground. Ask how it will be charged, before you sign.
- Comparing unlike quotes. One may include flashing, ice barrier and drip edge, and another may not. Ask for the same scope from each.
- Trusting one number from a website. Published figures differ by a factor of three for the same roof, and this page's own source is a contractor-site estimate.
- Going over an old layer without asking. It looks cheaper, but it can hide damage and may not be allowed where you are.
Questions
How much does a new roof cost for a 1,200 sq ft house?
About $7,400 to $18,800 for a single-storey 1,200 square foot footprint at 6 in 12, in architectural asphalt with one layer torn off, at the baseline region. That is about 13.4 squares. The range is wide because published figures disagree, so use it to check quotes.
What is the roof cost per square?
About $450 to $1,250 per square installed for architectural asphalt, by Inch Calculator's estimate, plus $100 to $150 per square to tear off one layer. A square is 100 square feet of roof. These are contractor-site figures, not measured data.
What does a metal roof cost per square foot?
About $4.50 to $17 per square foot for steel, and $6.50 to $21 for aluminum, installed, by Inch Calculator's estimate. A standing seam metal roof is at the upper end: Zonda's Cost vs. Value report has one defined 30 square job at $51,865.
Does tear-off add to the cost?
Yes, about $100 to $150 per square for each layer. It also exposes rotten decking, which is an extra cost you cannot see from the ground. Some areas limit how many layers a roof can carry, so ask a local roofer about going over an old layer.
Metal or shingles?
Shingles cost less up front, and metal costs more. On Zonda's Cost vs. Value figures, one defined job of 30 squares is $31,871 in asphalt and $51,865 in standing seam metal. Weigh up how long you plan to stay, and ask your roofers about expected life.
Why do online roof prices vary so much?
Because each one is pricing a different job. Omni's figures imply $6,000 to $12,000 for 30 squares, Inch Calculator's $13,500 to $37,500, and Cost vs. Value's fully specified job is $31,871. No published price series exists, so we show the range and say where it comes from.
This roof cost is a planning range built from a contractor-site estimate, and it is wide because published numbers disagree. Prices vary by region, crew and season. Rotten decking, permits and disposal can all add to it. Only a written quote from a licensed roofing contractor is binding, so use this to check quotes, never as a stand-in for one.
Sources and review
- Cost to replace a roof, Inch Calculator, updated 2023, read November 2026.
- Cost vs. Value: roofing replacement, asphalt shingles, Zonda, via JLC, 2025.
- Cost vs. Value: roofing replacement, metal, Zonda, via JLC, 2025.
Checked in November 2026. Spotted a wrong number? Report it and it goes in the corrections log.
How this is calculated
Every figure below is read from the code that produces the answer, so what is written here is what the calculator ran. The constants were last checked against their sources in November 2026.
The arithmetic
Squares
Squares = Footprint × √(1 + (Pitch ÷ 12)²) ÷ 100
- √(1 + (Pitch ÷ 12)²)
- The pitch multiplier, which allows for the slope
Worked through: 1200 × 1.118 ÷ 100 = 13.4 squares
Range
Cost = Squares × (Material + Tear-off × Layers) × Region
- Material
- Installed dollars per square, low and high
- Tear-off
- Dollars per square for each old layer
Worked through: 10 × (450 + 100 × 1) × 1 = 5500
The constants, and where they come from
COST_PER_SQUARE
Modelled from published dataInstalled cost per square, low and high, by material
- threeTab
- 425, 825
- architectural
- 450, 1250
- wood
- 800, 1430
- steel
- 450, 1700
- aluminum
- 650, 2100
- tile
- 500, 1800
- slate
- 1200, 2200
Applies to: United States, a contractor-site estimate and not measured data
Source: Cost to replace a roof, Inch Calculator, published 2023-07, read 2026-11. This source is about 3 years old, and it is the one the figure rests on.
Inch Calculator's page shows a 2023 update date with 2026 branding, so treat it as older than its label. Omni's figures are far lower and Cost vs. Value's defined job is near the top of this range, which is why the result is a wide range.
TEAR_OFF_PER_SQUARE
Modelled from published dataCost to tear off per square, low and high, for each layer
- 0
- 100
- 1
- 150
Applies to: One layer is the source's figure. Multiplying for a second layer is our own model
Source: Cost to replace a roof, Inch Calculator, published 2023-07, read 2026-11. This source is about 3 years old, and it is the one the figure rests on.
We found no published figure per layer, so two layers is simply double, which may be a little high or low on a real job.
PROJECT_MULTIPLIER
ModelledMultiplier by United States region, applied to this page's modelled rates
- northeast
- 1.1
- southeast
- 0.94
- midwest
- 0.97
- southwest
- 1
- west
- 1.13
Applies to: United States, five broad regions
No published figure exists for this. It is derived, and the derivation is below rather than a citation to something that does not say it. Last checked in November 2026.
The site's own model, shared across cost calculators. No published series was found. It is a broad adjustment, and your own quotes are what count.
SQ_FT_PER_SQUARE
DefinitionalSquare feet in one roofing square
Applies to: Definitional, everywhere
True by definition, so there is nothing to cite. The derivation is below.
A square is the trade's name for 100 square feet of roof.
INCHES_OF_RUN
DefinitionalThe run a pitch is stated against, in inches
Applies to: Definitional, everywhere
True by definition, so there is nothing to cite. The derivation is below.
A pitch of 6 in 12 means 6 inches of rise over 12 inches of run, by the way the trade writes it.
What the labels mean
- Modelled from published data:
- derived rather than measured, calibrated against the source named beside it.
- Modelled:
- derived rather than measured, and the derivation is shown.
- Definitional:
- true by definition, like the number of inches in a foot, so there is nothing to cite.
If a figure here looks wrong, it may be. Tell us what you found and we will check it against the source and publish a correction if it needs one. How constants are chosen and how often they are reviewed is set out in our methodology.
How to use the roof replacement cost calculator
- 1
Measure or estimate the area under the roof
- 2
Find the pitch
- 3
Choose your material and how many old layers come off
- 4
Set your region
- 5
Use the range to judge your quotes, and get at least three in writing
What this calculator assumes
Every estimate here rests on the assumptions below. Where your job differs from one of them, the figure will differ too.
- The whole roof has one pitch. A mixed roof should be split into planes
- Per-square prices are installed, from one contractor-site estimate, and include no decking repairs
- Tear-off is priced per layer. Doubling it for a second layer is our own model
- Typical is simply the middle of the range, not a measured average
Pro tips
- Get at least three written quotes, with the same scope in each
- Ask how decking repairs are priced before work starts
- Check whether your contractor pulls the permit, and is licensed where you live