Roofing calculator: your roof cost, low to high

Your roof is leaking or past 20 years, and you want a price before a roofer comes out. For a typical 1,800 sq ft house with asphalt shingles the answer is about $6,900 to $24,100, likely $15,500. Put your own footprint and slope in below and the three numbers move.

Your estimate: low, likely, high

Low is a simple one-story roof with a cheap shingle; high is a steep roof, a premium shingle and a busy crew. Budget the likely number, so a quote well above it needs a line-item reason, and a quote well below it needs a license check.

Your home's size and slope

Enter the footprint of the house, the area of the ground it covers. Count the garage if the roof runs over it. Pick the slope as rise per 12 inches of run. If you don't know it, 6/12 is a common middle value.

Pick a material

Each material uses its own price band per square foot of roof surface. Asphalt is $3.44 to $12, standing seam metal $8 to $14, flat membranes $8.04 to $10.29, and tile $19.01 to $26.03. So the same roof costs two to three times more in tile than in asphalt; pick the material before you compare quotes.

Tear-off and layers

One layer of old shingles is normal and is inside the material price. Each extra layer adds $1 to $5 per sq ft for removal and disposal, so a second layer on a 2,000 sq ft roof adds about $2,000 to $10,000. Ask every roofer how many layers they found and get tear-off as its own line on the quote.

How the roofing calculator works

Footprint times the slope factor gives the roof surface. A 6/12 slope multiplies by 1.118, so 1,800 sq ft of footprint becomes about 2,012 sq ft of roof. That area times the low and high price per square foot gives the range. Likely is the middle.

Prices come from This Old House for asphalt and tear-off, NerdWallet for metal, and Homewyse for tile. Flat roofs use the Homewyse membrane figure.

What changes the number

• Rotten decking found during tear-off is billed by the sheet.
• Valleys, dormers and chimneys add flashing and labor.
• Two-story walls need more ladders, staging and time.
• A storm that hits the whole town fills every crew's calendar for weeks, so a quote booked today holds a place in line while a leak keeps soaking the decking.

Angi puts the national average at $4 to $11 per sq ft in its 2026 replacement guide, which sits inside the asphalt band above.

Worked examples

1. Dana, 1,800 sq ft footprint, 6/12, asphalt, one layer: about 2,012 sq ft of roof, $6,900 to $24,100, likely $15,500.
2. Glen, 1,800 sq ft footprint, 6/12, standing seam metal: $16,100 to $28,200, likely $22,200.
3. Earl, 1,400 sq ft footprint, 8/12, asphalt, two old layers: about 1,683 sq ft of roof, $7,500 to $28,600.

Get quotes for this estimate

The roof size from your estimate is copied into the form below. Three licensed roofers near your ZIP can then quote the same job, so you can compare like with like.