Turn a footprint and pitch into a roofing estimate: roof area, squares with waste, shingle bundles, materials, labor and tear-off, a total price per square, and a quote line to paste.
For roofers and roofing contractors · updated October 2026
An estimate for a simple roof. Waste applies to materials only; decking, flashing, permits and disposal are extra.
How to use this roofing calculator
- Enter the building's length and width plus the overhang, or type the footprint in square feet if you already have it (overhangs included).
- Pick the roof pitch. The calculator applies the matching pitch multiplier to turn the flat footprint into real roof area.
- Set a waste allowance. 10% suits a simple gable roof; go higher for hips, valleys and dormers.
- Choose 3-tab, architectural or metal. Each fills in a starting materials and labor price per square that you can overwrite with your own.
- Add tear-off layers if the old roof comes off, then copy the quote line into your estimate or invoice.
How to calculate roofing squares
Roofers price by the square: 100 sq ft of roof surface. A roofing square calculator needs three things: the footprint the roof covers, the pitch, and a waste allowance.
Worked example: a 50 × 30 ft house, 6/12 pitch
Overhangs are 12 inches, the roof is architectural shingles at $175 per square for materials and $325 per square for labor, with 10% waste and one layer to tear off at $150 per square.
- Footprint with overhangs: 52 × 32 = 1,664 sq ft.
- Roof area: 1,664 × 1.118 = 1,860 sq ft, or 18.6 squares.
- With 10% waste: 20.46 squares × 3 bundles = 61.4, so you order 62 bundles.
- Materials: 62 ÷ 3 × $175 = $3,616.67. Labor: 18.6 squares × $325 = $6,045. Tear-off: 18.6 × $150 = $2,790.
- Total: $12,451.67, or about $669 per square installed.
Waste applies to materials only, because you buy the extra shingles but you only lay and tear off the real roof. GAF's guide to shingle bundles notes that most standard 3-tab and architectural shingles come three bundles to a square, but some specialty lines need four or even five, so check the wrapper. Its Woodland line, for example, is four bundles per square.
Roof pitch multiplier table
Pitch is rise over a 12-inch run. The multiplier is pure geometry, the square root of 1 + (rise ÷ 12)², so you can check any value yourself. The last column applies it to the 1,664 sq ft footprint from the example.
| Pitch | Angle | Multiplier | Roof area from 1,664 sq ft |
|---|---|---|---|
| Flat (0/12) | 0° | 1.000 | 1,664 sq ft |
| 3/12 | 14.0° | 1.031 | 1,715 sq ft |
| 4/12 | 18.4° | 1.054 | 1,754 sq ft |
| 5/12 | 22.6° | 1.083 | 1,803 sq ft |
| 6/12 | 26.6° | 1.118 | 1,860 sq ft |
| 7/12 | 30.3° | 1.158 | 1,926 sq ft |
| 8/12 | 33.7° | 1.202 | 2,000 sq ft |
| 9/12 | 36.9° | 1.250 | 2,080 sq ft |
| 10/12 | 39.8° | 1.302 | 2,166 sq ft |
| 12/12 | 45.0° | 1.414 | 2,353 sq ft |
Roofing cost per square: 2026 price ranges
These ranges come from HomeGuide's roofing labor and roof replacement cost guides, updated November 2025 and read in October 2026. The calculator's starting prices sit inside them.
| Material | Materials per square | Labor per square | Installed per sq ft |
|---|---|---|---|
| 3-tab asphalt shingles | $80 – $130 | $200 – $300 | $3 – $5 |
| Architectural shingles | $100 – $250 | $300 – $350 | $4 – $6 |
| Metal | $100 – $800 | $400 – $800 | $5 – $16 |
| Tear-off (shingles or metal) | – | $100 – $300 | $1 – $3 |
Other line items to price separately: underlayment at $0.10 to $0.80 per sq ft for materials, decking replacement at $2 to $5 per sq ft installed, drip edge at $1.50 to $3 per linear foot installed, permits at $100 to $500, and a 10-yard dumpster at $220 to $580 per week. Housecall Pro's 2026 roofing guide prices tear-off at $1 to $3 per sq ft per additional layer, which is why the calculator multiplies tear-off by the number of layers.
How to price a roofing estimate
The calculator gives you direct costs per square. Before you send a number, make sure it also covers overhead and profit.
- Use loaded labor. Your labor per square should include payroll taxes, insurance and the crew's time on site, not just wages.
- Add overhead. Trucks, insurance, software and office time have to come out of every job. Spread them across the squares you install in a typical month.
- Price to a margin. Housecall Pro's roofing guide uses break-even cost ÷ (1 − target margin), with a 20% to 40% range. Jobber's guide says most roofing companies net 5% to 10%, while well-run ones target 12% to 15% net.
- Charge for difficulty. Steep pitches, two-story eaves, many valleys and long carries all add labor. Raise the labor per square for those jobs rather than padding the waste.
- Check your price per square. Compare it with recent jobs of the same type. If it drifts far from what you usually charge, find out why before you send the estimate.
Markup and margin aren't the same thing. A 25% markup on cost is a 20% margin on the price. The markup calculator converts between them.
What homeowners pay for a roof replacement
Roof replacement cost calculators aimed at homeowners use national ranges like these. HomeGuide puts the average replacement at $5,700 to $16,000, or $300 to $600 per square including materials and installation, with a national average of $10,800.
| House size | Roof size (6/12 pitch) | Average cost to reroof |
|---|---|---|
| 1,500 sq ft | 1,675 sq ft | $5,000 – $10,100 |
| 2,000 sq ft | 2,235 sq ft | $6,700 – $13,400 |
| 2,500 sq ft | 2,795 sq ft | $8,500 – $16,800 |
| 3,000 sq ft | 3,355 sq ft | $10,100 – $20,100 |
Source: HomeGuide, single-story homes with asphalt shingles. Labor makes up 50% to 70% of the cost to replace a roof, according to the same source. Homeowners comparing quotes often look at the total only, so an itemized estimate makes it easier to show why your number is what it is.
Common roofing estimate mistakes
- Using the house's living area as the roof area. A two-story home has half the footprint, and overhangs and pitch add area on top. Measure the footprint the roof covers.
- Forgetting the pitch multiplier. A 6/12 roof is almost 12% bigger than its footprint, and a 12/12 roof is about 41% bigger.
- Applying waste to labor. Waste is extra material. Charging labor on waste squares quietly inflates the bid and is hard to explain.
- Assuming three bundles everywhere. Heavier and specialty shingles can come four or five bundles to a square.
- Leaving out tear-off layers. Two layers mean two passes of removal and more disposal. Ask, or check at the inspection.
- Skipping the extras. Underlayment, drip edge, flashing, vents, permits and the dumpster belong on the estimate as their own lines.
How to put a roofing estimate on an invoice
Send the client a quote first, as a regular document or message. Our guide to estimates vs invoices covers when to use which. When the job is done, invoice the same lines, each as quantity × rate, so the client can match them to the quote. An itemized invoice gets questioned less:
- Architectural shingles: 62 bundles (20⅔ squares at $175 per square) = $3,616.67
- Installation labor: 18.6 squares × $325 = $6,045
- Tear-off and disposal, 1 layer: 18.6 squares × $150 = $2,790
- Underlayment, drip edge, flashing, permits: one line each.
In Onigiri, add these line items to your invoice, set any tax rate, and send it by email, as a link or as a PDF. You'll see when it's Sent, Overdue or Paid. The free plan includes 3 invoices a month, and PRO adds item templates for your standard roofing lines and card payments through your own Stripe account. The contractor invoice template shows a layout that works for roofing jobs.
Roofing calculator FAQ
How do I calculate roofing squares?
Multiply the footprint the roof covers, overhangs included, by the pitch multiplier, then divide by 100. A 1,664 sq ft footprint at 6/12 pitch is 1,664 × 1.118 = 1,860 sq ft, or 18.6 squares.
How many bundles of shingles are in a square?
Most standard 3-tab and architectural shingles come three bundles to a square, according to GAF. Some specialty and heavier shingles need four or five, so check the coverage printed on the bundle.
How much waste should I add for a roof?
GAF says contractors usually include a 10% to 15% waste factor. Use the low end for simple gable roofs and more for hips, valleys and dormers.
What is the pitch multiplier for a 6/12 roof?
It's 1.118, the square root of 1 + (6 ÷ 12)². Multiply the footprint by 1.118 to get the roof's surface area.
How much does roofing labor cost per square?
HomeGuide lists $200 to $300 per square for asphalt shingles, $300 to $350 for architectural shingles and $400 to $800 for metal, not including materials.
How much does a roof replacement cost?
HomeGuide puts the average at $5,700 to $16,000, or about $3 to $6 per square foot installed for asphalt shingles. Metal runs $5 to $16 per square foot installed.
How much should I charge to tear off a roof?
Cost guides put shingle or metal tear-off at $1 to $3 per square foot, or $100 to $300 per square. Housecall Pro applies that range per additional layer, so price two layers as two passes.
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Estimate it, then invoice it
Add squares, labor and tear-off as line items, send the invoice by email or link, and track when it’s paid.
