How to estimate a roof replacement, the complete contractor's guide
Writing a roof estimate isn't just plugging numbers into a calculator. The math is straightforward, what trips up most contractors (and costs them jobs) is missing a step, underestimating waste, or pricing labor wrong for the pitch. This guide walks you through every step, with the formulas you actually need.
Step 1, Measure the roof
You need the total square footage of the roof surface (not the floor plan / footprint). Three ways to do this:
- Satellite + AI tracingfastest, ~2 minutes. Tools like RoofMetric's AI detection click on a roof in satellite view and trace the outline, returning surface area with pitch already factored in.
- On-roof tape measurementmost accurate, slowest. Required for complex Mansards, dormers, gambrels.
- Drone photogrammetrygood for properties where satellite is poor or you want fly-over photos for the customer.
For residential reroofs, AI satellite tracing is accurate to within 2 to 3% of surveyor-grade measurement, plenty good enough for a competitive bid.
Step 2, Calculate squares
A "square" in roofing means 100 square feet of roof surface. It's the industry standard pricing unit.
Example: 3,200 sq ft of roof = 32 squares.
Step 3, Factor in pitch (slope)
Steeper roofs need more material per linear foot of floor area, and more labor. If you measured from a floor plan rather than a sloped surface, you need to multiply by the pitch factor:
4/12 = 1.054 · 6/12 = 1.118 · 8/12 = 1.202 · 10/12 = 1.302 · 12/12 = 1.414
Most residential roofs are 4/12 to 8/12. Anything steeper than 8/12 typically commands a 20 to 35% labor premium because of the safety setup required.
Step 4, Add waste factor
You buy materials in bundles or rolls; you cut them to fit. Waste is real and varies by roof complexity:
- Simple gable roof: 10% waste
- Hip roof: 12 to 14% waste (more cuts at corners)
- Complex roof with valleys, dormers: 15 to 18% waste
- Architectural shingles in scattered pattern: add 2 to 3% more
Step 5, Price the materials
You're buying more than just shingles. A complete shingle reroof typically includes:
- Architectural shingles: $100 to $150 per square (varies by brand/grade)
- Underlayment (synthetic): $25 to $40 per square
- Ice & water shield: $80 to $120 per square (used at eaves and valleys, ~6 ft from edge)
- Drip edge: $2 to $3 per linear foot of perimeter
- Ridge cap: $35 to $55 per linear foot of ridge
- Starter shingles: $35 to $55 per linear foot of eaves
- Flashings (chimney, sidewall, vent): $50 to $200 each unit
- Vents (ridge, box, soffit): $30 to $80 each
- Nails, sealants, misc: $5 to $10 per square
Step 6, Tear-off and disposal
Most reroofs require removing the existing material first. Costs:
- Tear-off labor: $50 to $80 per square (single layer); $80 to $120 per square (double layer)
- Dumpster: $400 to $700 for a 20-yard (sufficient for most residential reroofs)
- Disposal fees: usually included in dumpster price; some markets charge by tonnage above a baseline
Step 7, Labor for installation
Installation labor varies hugely by region and pitch. Typical ranges (architectural shingles, average complexity):
- Low pitch (under 6/12): $200 to $300 per square
- Standard pitch (6/12 to 8/12): $250 to $350 per square
- Steep (9/12 to 12/12): $350 to $500 per square
- Walkable but 12/12+: $500 to $700 per square (rope/harness required)
Add 15 to 25% for complex hip roofs with multiple valleys or for steep dormers requiring scaffolding.
Step 8, Add overhead, profit, and contingency
Your subtotal is materials + tear-off + disposal + labor. Then you apply markup:
- Overhead (insurance, vehicles, office, payroll burden): typically 12 to 18%
- Profit margin (target net): 10 to 15% for solo contractors, 8 to 12% for established companies
- Contingency (unforeseen rot, decking replacement): build 1 to 2 sheets of OSB at $50 to $80 each into the estimate, or add a "decking replacement: $80/sheet as needed" line item
Final Price = Direct Costs × (1 + Markup %)
Step 9, Write the estimate
A professional estimate has:
- Your company brandinglogo, license number, contact info at the top
- Customer name and project address
- Itemized line items with quantities, units, and per-unit prices (NOT a single lump sum, customers want to see what they're paying for)
- Material specsbrand, grade, color of shingles, underlayment type, etc.
- Scope of work in plain language
- What's NOT includeddecking replacement beyond contingency, gutter work, etc.
- Payment termsdeposit %, milestones, final balance
- Warrantymanufacturer (typically 30-50 years) and your workmanship (typically 5-10 years)
- Expiration datemost contractors use 30 days
- Clear call to action"Reply to accept" or a signature link
Step 10, Send fast, follow up faster
Speed matters. Studies show contractors who deliver estimates within 24 hours win 2x more bids than those who take 3+ days. If you can deliver a polished, signed-via-link estimate while you're still in the customer's driveway, your close rate goes through the roof.
The rest of the job, not just the measurement
An estimate is only worth what happens after you send it. Most of what goes wrong there is a phone call nobody got to and a glovebox of receipts nobody sorted.
Front Desk: a business line that rings your phone
A real business phone number for your company, built in. Place and answer calls, keep a shared call log the whole team can see, and text customers from a number that is not your cell. Incoming calls ring your iPhone with the standard call screen, on the lock screen, whether the app is open or closed. Every paid plan includes a real business phone number, free, with 120 minutes a month. See how Front Desk works.
Tax Central: expenses, receipts and W-9s
Track business expenses by job and by Schedule C category, so profit per job is a number you can see rather than one you work out in January. Scan a receipt with your camera, and collect a signed W-9 from every subcontractor you pay. See what each plan includes.
Front Desk and Tax Central, answered
Does RoofMetric include a business phone number?
Yes. Every paid plan includes a real business phone number at no extra cost, with 120 minutes a month. You pick your own local number in about thirty seconds. Calls and texts run from the app or a browser and always show the business number rather than a personal cell, and every call files itself against the customer it came from.
What does the AI receptionist actually do?
Turn on the AI receptionist and she answers when you cannot. She knows your services, your hours and your service area, books estimates straight onto your calendar, takes a message when the caller needs a person, and emails you the recording and a summary. Both sides are told the call is recorded, and recording can be switched off. It is optional: the business line works on its own with your team answering.
Do incoming calls ring the phone when the app is closed?
Yes, on iPhone. Front Desk calls ring with the standard iPhone call screen, on the lock screen, whether the app is open, in the background or closed, and appear in Recents like any other call. An Android build is in development with no release date announced.
Can I track expenses and 1099 paperwork in RoofMetric?
Yes, in Tax Central. Track business expenses by job and by Schedule C category, scan a receipt with your camera to fill in the vendor, amount and category, and collect a signed W-9 from every subcontractor you pay. Taxpayer numbers are encrypted and shown only as the last four digits.
Skip the spreadsheet
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