Roof Cost Calculator
Reviewed by the My Roof Pitch editorial team · Updated · Free, no sign-up, works offline after first load
Roof cost is the sloped area in squares multiplied by the combined material and labour rate per square, plus tear-off and disposal. At $450 per square installed, a 20-square roof costs about $9,000 before tear-off, which adds $100 to $150 per square.
Key takeaways
- Price a roof per square (100 sq ft of sloped area), never per square foot of house footprint.
- A 6:12 pitch makes the roof 11.8% larger than the plan area before overhangs are added.
- Tear-off and disposal typically adds $100–$150 per square per layer removed.
- Pitch above 7:12, second storeys and cut-up roofs raise labour by 8–50%, and this tool applies those multipliers for you.
- Carry a 10% contingency: deck replacement found at tear-off is the most common change order.
Your measurements
Enter the values you know — results update live.
Plan area of the building including overhangs.
Steeper roofs cost more per square because access slows the crew down.
What the covering itself costs per 100 sq ft, delivered.
Installation labour per 100 sq ft. Ask a local contractor for their rate.
Set to 0 for new construction or an overlay.
Hips, valleys, dormers and skylights all slow the crew down.
Storeys and site access drive staging, hoisting and safety setup.
Analysis
Live results from your measurements.
This is a planning estimate built from the rates you entered. Get at least three written local quotes before committing.
Show the working
- Sloped area:
1,600 × 1.118= 1,789 sq ft - Squares:
1,789 ÷ 100= 17.89 - Material:
17.89 × 1.1 × 150= $2,952 - Labour difficulty:
steep 1 × complexity 1 × access 1= × 1 - Labour:
17.89 × 300 × 1= $5,367 - Tear-off:
17.89 × 125= $2,236 - Total:
material + labour + tear-off + $900 extras= $11,454 - Budget:
$11,454 × 1.1 contingency= $12,600 - Range:
low / likely / high= $10,501 / $11,454 / $12,823
What this calculator does
Roof cost is driven by four things: how many squares of surface you have, what the covering costs, what local labour charges to install it, and whether the old roof has to come off first. Everything else — flashing, vents, permits, a chimney cricket — is comparatively small. Pitch matters twice over: it enlarges the area through the pitch multiplier, and above about 7:12 it slows the crew down enough that labour rates rise. This calculator makes that second effect explicit with a labour difficulty multiplier that combines steepness, roof complexity (hips, valleys, dormers, skylights) and access (storeys, tight sites), because those three factors explain most of the spread between two quotes on identically sized roofs. Because material and labour rates vary enormously by region, the tool asks you for the rates rather than inventing them: drop in a supplier price and a contractor's per-square labour rate and the estimate becomes local rather than national. The output is deliberately split into material, labour, tear-off, extras and a contingency line so you can line it up against a written bid item by item, and a low/likely/high band so you know how much of the number is genuinely uncertain.
How to use it
- Calculate the sloped roof area and convert it to squares by dividing by 100.
- Get a material rate per square from a supplier or a recent quote.
- Get a labour rate per square from a local contractor.
- Set roof complexity and access so the labour difficulty multiplier reflects your building.
- Add a tear-off and disposal rate per layer being removed, or set it to zero for new work.
- Add a flat allowance for flashing, vents, permits and any structural repair.
- Hold a contingency of about 10% for deck repair discovered at tear-off.
- Compare the result against at least three written quotes.
The formula
Total cost
total = squares × (material rate × (1 + waste) + labour rate × labour factor + tear-off rate) + extras
Waste is applied to material only, because labour is paid on installed area.
Labour difficulty multiplier
labour factor = steep factor × complexity × access, where steep factor = 1 + (pitch − 7) × 0.05 above 7:12 (capped at 1.50)
Steep, cut-up and hard-to-reach roofs take more crew hours per square. This is where two quotes on the same area legitimately diverge.
Recommended budget
budget = total × (1 + contingency)
A 10% contingency covers the deck sheets, flashing and rot repair usually found once the old covering is off.
Cost per square
cost per square = total cost / squares
The figure to compare directly against contractor quotes.
Three-point estimate
low = material × 0.95 + labour × 0.90 + tear-off × 0.90 + extras × 0.95; high = material × 1.10 + labour × 1.15 + tear-off × 1.10 + extras × 1.05
A planning range around the likely total to cover regional rate swings and unknowns.
Worked example
A 1,600 sq ft footprint at 6:12, simple gable, single storey, $150 material, $300 labour, $125 tear-off, $900 extras, 10% waste, 10% contingency.
- Area: 1,600 × 1.1180 = 1,789 sq ft, or 17.89 squares
- Material: 17.89 × 1.10 × $150 = $2,952
- Labour factor: 1.00 steep × 1.00 complexity × 1.00 access = 1.00
- Labour: 17.89 × $300 × 1.00 = $5,367
- Tear-off: 17.89 × $125 = $2,236
- Total: $2,952 + $5,367 + $2,236 + $900 = $11,455
- Budget with 10% contingency: $12,601
- Range: low ≈ $10,650 / likely $11,455 / high ≈ $12,560
About $11,455, or $640 per square — roughly $10,650 to $12,560 on rate swings, and worth budgeting $12,600 with contingency.
Reference chart
| Roof size | Squares | Estimated installed cost |
|---|---|---|
| 1000 sq ft | 10 | $5,750 |
| 1500 sq ft | 15 | $8,625 |
| 2000 sq ft | 20 | $11,500 |
| 2500 sq ft | 25 | $14,375 |
| 3000 sq ft | 30 | $17,250 |
| 4000 sq ft | 40 | $23,000 |
Typical installed cost ranges by roofing material (US, per square)
| Material | Installed cost per square | Expected life |
|---|---|---|
| Three-tab asphalt | $350 – $550 | 15–20 years |
| Architectural asphalt | $450 – $750 | 25–30 years |
| Exposed-fastener metal | $600 – $1,000 | 30–45 years |
| Standing seam metal | $1,000 – $1,800 | 40–70 years |
| Concrete tile | $900 – $1,800 | 50+ years |
| Natural slate | $1,500 – $3,000 | 75–150 years |
Common mistakes
- Pricing against the house footprint. A 6:12 roof is 12% larger than the plan area before overhangs.
- Leaving out tear-off. Removing one layer of shingles typically adds $100 to $150 per square.
- Assuming a second layer can be overlaid. Most codes allow at most two total layers, and an overlay hides deck damage.
- Forgetting deck replacement. Rotten sheathing found at tear-off is the most common change order on a re-roof.
- Comparing quotes on total price alone rather than cost per square with matching scope.
- Ignoring steep-slope and multi-storey access surcharges, which are real and legitimate.
- Treating a cut-up roof like a simple gable. Valleys, dormers and skylights add cutting, flashing and waste.
- Budgeting the estimate exactly, with no contingency for what appears once the roof is stripped.
Assumptions and limits
- All rates are the ones you enter — the tool does not assume any market price.
- Waste is applied to material cost only.
- The labour difficulty multiplier applies to labour only, never to material or disposal.
- Steep-slope loading starts above 7:12 and is capped at 1.50 to stay realistic on very steep roofs.
- Estimates exclude structural repair, skylight replacement and gutter work unless included in extras.
- Published cost ranges in the comparison table are national indicative figures, not quotes.
Frequently asked questions
How much does a new roof cost?
Most US asphalt shingle re-roofs land between $450 and $750 per square installed, so a typical 20-square roof runs $9,000 to $15,000 including tear-off. Metal and tile cost two to four times more.
How much does roof tear-off cost?
Removing and disposing of one layer of asphalt shingles typically adds $100 to $150 per square. A second layer, or heavy tile and slate, costs considerably more to remove and haul away.
Does roof pitch affect cost?
Yes, twice. A steeper pitch increases the surface area you pay for, and above roughly 7:12 crews need staging and fall protection, which raises the labour rate by 20% or more.
Is it cheaper to overlay than tear off?
An overlay saves the tear-off cost, but it adds weight, shortens the new roof's life by trapping heat, and hides any deck damage. Most codes allow no more than two total layers.
How do I compare roofing quotes fairly?
Convert each quote to a cost per square and confirm the same scope: number of layers removed, underlayment type, ice and water coverage, flashing replacement, ventilation and warranty terms.
What hidden costs come up on a re-roof?
Deck replacement is the big one, usually charged per sheet of plywood. Chimney flashing, skylight curbs, added ventilation and permit fees are the other four that regularly appear as change orders.
How much does it cost to replace a 2,000 square foot roof?
A 2,000 sq ft footprint at 6:12 is about 22.4 squares of roof. At $450 to $750 per square installed that is roughly $10,000 to $17,000 for asphalt shingles including one layer of tear-off, before deck repair.
Why is my roofing quote higher than an online estimate?
Online estimates assume a simple single-storey gable. Extra storeys, steep pitch, valleys, dormers and skylights raise crew hours per square by 10% to 50%, which is what the labour difficulty multiplier in this calculator models.
How much contingency should I hold for a roof replacement?
Hold about 10% of the contract value. Plywood deck sheets, rotten fascia, chimney flashing and unexpected extra layers are all discovered after tear-off begins and are almost always billed as extras.
Is a metal roof worth the extra cost?
Standing seam costs roughly two to three times an architectural asphalt roof but lasts two to three times as long, so lifetime cost per year is similar. It wins on longevity, wind resistance and reduced re-roof disruption, not on upfront price.
Does insurance cover a roof replacement?
Insurance typically covers sudden damage such as hail or wind, not wear-out. Claims are usually paid at actual cash value or replacement cost depending on your policy, with your deductible and any code-upgrade allowance affecting the payout.
Related guides
- Common Roof Pitches Explained: 3:12 Through 12:12A pitch-by-pitch breakdown of every slope you will meet on a house — what each one costs, what it can be covered with, and which climates it suits.
- Metal Roof Pitch: Minimums, Panel Lengths and Cost by SlopeMetal covers a wider slope range than any other roofing, but only if you match the profile to the pitch. Minimums, panel take-off, weight and the cost curve across slopes.
- Roof Replacement Cost: How Roofing Quotes Are Actually BuiltRoofers price per square, not per square foot of house. Here is how material, labour, tear-off, steepness and access combine into the number on your quote — and where the extras hide.
Last updated 2026-08-05. Results are estimates for planning and are not a substitute for a licensed engineer or local code review.