Guides

How to Estimate a Roofing Job (With a Worked Example)

Measure the roof in squares with the right pitch factor, add waste, work out bundles and underlayment, price labor, overhead and margin, and write an estimate that holds up.

Ijharul Islam October 21, 2026 9 min read

How to estimate a roofing job, in short: measure each roof plane, multiply by the pitch factor (1.118 for a 6/12 roof), divide by 100 to get squares, and add 10% to 15% for waste. Then price materials (three bundles a square for most architectural shingles), labor, tear-off and disposal, permits and overhead, and divide the total cost by one minus your target margin.

More on this topic: Pricing, estimates and getting paid, every guide in one place.

Roofing estimates go wrong in two places: the measurement and the margin. Miss the pitch or the waste and you run short of shingles on day two; price with a markup when you meant a margin and you work the summer for less than you planned. This guide walks through a residential tear-off and re-roof step by step, with the manufacturer figures behind each number and a worked example you can copy into a spreadsheet.

Key takeaways

A square is 100 square feet of roof surface. Measure plan area, then multiply by the pitch factor.
Pitch factors (Owens Corning): 4/12 = 1.054, 6/12 = 1.118, 8/12 = 1.202, 10/12 = 1.302, 12/12 = 1.414.
Waste: 10%–15% is the manufacturer rule of thumb; complex, cut-up roofs need more.
Materials: about 3 bundles per square for architectural shingles, synthetic underlayment at 10 squares a roll.
Margin, not markup: a 15% margin needs a 17.6% markup. Jobber's 2026 guide says well-run roofers target 12%–15% net.
Put a per-sheet decking price on every estimate, because rotten decking only shows once the old roof is off.

What goes into a roofing estimate?

A roofing estimate is built from six cost groups. Price each one separately so you can see where a job made or lost money:

Cost group	What's in it
Materials	Shingles, underlayment, starter strip, ridge cap, drip edge, ice and water barrier where needed, vents, pipe boots, flashing, nails
Labor	Tear-off, deck repair, install, cleanup, at loaded hourly cost (wage plus payroll taxes, workers' comp, benefits)
Disposal	Dumpster or haul-away and dump fees, by the number of layers coming off
Permits and inspection	Whatever your jurisdiction charges for a re-roof permit
Equipment	Lifts, safety gear, rented equipment for the job
Overhead and profit	Your share of office, insurance, vehicles and sales, plus margin

How do you measure a roof in squares?

Measure the plan (bird's-eye) area of each roof plane including overhangs, multiply it by the pitch factor for its slope, and divide by 100. One roofing square equals 100 square feet of roof surface. Aerial measurement reports and drones save the climb, but check the pitch on site. Owens Corning's slope factors:

Pitch	Factor	Pitch	Factor
3/12	1.031	8/12	1.202
4/12	1.054	9/12	1.250
5/12	1.083	10/12	1.302
6/12	1.118	11/12	1.357
7/12	1.158	12/12	1.414

The factor is √(1 + (rise ÷ 12)²), so you can work out any pitch yourself. Be careful with the pitch tables in some roofing guides: several widely shared tables list 6/12 as 1.24, which overstates the roof by about 11%. The free roof pitch calculator gives the multiplier for any pitch, plus the hip and valley factor and rafter lengths.

How much waste should you add?

Add 10% to 15% for waste, which Owens Corning calls a good rule of thumb; IKO gives the same range. Use the low end on a simple gable roof and the high end, or more, on hips, valleys, dormers and lots of short runs. Owens Corning also says to add 10% to 15% to underlayment. The free roofing calculator runs the whole count, from squares with waste to bundles, underlayment rolls, drip edge, starter and ridge cap.

How do you work out the materials?

Material	Rule (manufacturer figures)	How to count
Architectural shingles	3 bundles per square (Owens Corning, IKO)	Squares including waste × 3
Synthetic underlayment	Typically 10 squares per roll; #15 felt about 4 squares (Owens Corning)	Roof squares plus 10%–15%, ÷ roll coverage
Starter strip	Owens Corning Starter Strip Plus: 105 lineal feet per bundle	Eaves (and rakes, if you start them there) ÷ 105
Ridge cap	Varies by product; check the bundle's lineal-foot coverage	Ridge and hip length ÷ coverage
Drip edge	Usually 10-foot pieces	Eaves and rakes ÷ 10, rounded up
Nails	4 per shingle; 6 in high-wind areas (Owens Corning)	Follow the shingle's installation instructions

How do you price labor and overhead?

Price labor from crew hours, not a per-square guess you inherited: crew size × days × hours × loaded hourly cost. Track actual hours per square on your last ten jobs and use that, adjusted for pitch (steep roofs are slower), layers to tear off and access. For overhead, Jobber's guide divides weekly overhead by weekly labor hours (its example: $900 ÷ 90 hours = $10 an hour) and adds that to each labor hour; ServiceTitan's divides total overhead by total direct costs to get a percentage. Use one method consistently.

A worked example: 6/12 tear-off and re-roof

A ranch house with 2,000 square feet of plan area, one layer to tear off, 180 feet of eaves and rakes and 40 feet of ridge. Material prices are examples; use your supplier's.

Line	Calculation	Cost
Roof area	2,000 × 1.118 = 2,236 sq ft = 22.4 squares
Order quantity	22.4 + 12% waste ≈ 25 squares
Shingles	75 bundles × $42	$3,150
Synthetic underlayment	3 rolls × $120	$360
Starter strip	2 bundles × $55	$110
Ridge cap	2 bundles × $70	$140
Drip edge	18 pieces × $12	$216
Nails, vents, boots, sealant	Allowance	$350
Labor	4 people × 2 days × 9 hours = 72 hours × $38 loaded*	$2,736
Dumpster and disposal	One layer	$550
Permit	Example; check your jurisdiction	$250
Overhead	72 labor hours × $25	$1,800
Total cost		$9,662
Price at 15% margin	$9,662 ÷ 0.85	$11,367, round to $11,375

*$38 is an example loaded rate; the BLS May 2025 median wage for roofers was $26.65 an hour before payroll taxes, insurance and benefits. A 15% markup on the same cost would give $11,111 and only a 13% margin. That gap, $256 here, is the difference between the job you priced and the job you meant to price. Add decking as a per-sheet price (for example, “$95 per 4×8 sheet of replaced decking”) rather than guessing a number into the total.

What profit margin should a roofing contractor aim for?

Jobber's 2026 roofing guide says well-run roofing companies target net margins of 12% to 15%, while most sit between 5% and 10%, and cites the National Roofing Contractors Association for a 6% average net margin in 2018. ServiceTitan's guide quotes a 10% to 20% range. Whatever your target, it's a net margin after overhead, so it only holds if your overhead line is honest. Good, better, best options (shingle line, underlayment, warranty level) let the customer choose a higher price without you discounting; see good, better, best pricing.

What should the written roofing estimate include?

Your business name, contact details and license number where your state requires it on bids and contracts (California and Florida do, for example).
Scope: layers to tear off, shingle brand, line and color, underlayment, ice and water barrier, flashing, vents and ridge.
Unit prices for unknowns: decking per sheet, extra layers per square.
Permits, cleanup and magnet sweep, and who pulls the permit.
Warranty: the manufacturer's and your workmanship warranty, in years.
Payment schedule and deposit, and how long the price is valid. See how much deposit to ask for.
Signature and date lines, or an online approval.

Insurance work is priced differently: it's often written in Verisk's Xactimate, claims estimating software that prices repairs from regional cost data updated monthly, so match its line items when you write a supplement. Then follow up: most roofing estimates aren't signed on the first visit. Our guide on following up on unsold estimates has the texts.

Mistakes that cost roofers money

Using plan area as roof area. On a 6/12 roof that undercounts by more than 10% before waste.
One waste factor for every roof. A cut-up hip roof eats far more than a simple gable.
Labor per square copied from someone else. Your crews, pitches and tear-offs are yours.
Markup mistaken for margin. Price with cost ÷ (1 − margin).
No unit price for decking. It turns a surprise into an argument.

Where CrewRobin fits

CrewRobin doesn't measure roofs; use your measurement report or tape and put the numbers on the quote. From there, its quotes let you send good, better, best options by text that the homeowner picks and signs online, follow-up texts go out on day 2, 5 and 10, and you can ask for a deposit (a percent or a fixed amount) paid by card through your own Stripe account. Website and Facebook leads get a text straight away, and you can mark up roof photos with arrows, circles and text. See how it works for roofers.

Frequently asked questions

How do you calculate roofing squares?

Measure the plan area of each roof plane including overhangs, multiply by the pitch factor (for example 1.118 for 6/12), add the planes together and divide by 100. Then add 10% to 15% for waste.

How many bundles of shingles are in a square?

Most architectural (laminated) shingles take 3 bundles per square, according to Owens Corning and IKO. Check the wrapper: some products differ.

What is a good profit margin for a roofing job?

Jobber's 2026 guide says well-run roofing companies target 12% to 15% net margin, while most land between 5% and 10%. ServiceTitan quotes 10% to 20%. Set yours after overhead, and price with cost divided by one minus the margin.

How much waste should I add to a roofing estimate?

Owens Corning and IKO both give 10% to 15% as the rule of thumb. Use the low end on simple gables and more on hips, valleys and dormers.

Should a roofing estimate include decking replacement?

Include it as a unit price per sheet rather than a fixed amount, because damaged decking usually can't be seen until the old roof is off. Say how many sheets, if any, are already in the price.

What software do insurance adjusters use for roofing estimates?

Many insurers and adjusters use Verisk's Xactimate, which prices repairs from regional cost data updated monthly. Matching its line items makes supplements easier to review.

Put it to work this week

Send roofing quotes with options the homeowner signs online, and let the follow-ups and deposit request run themselves. CrewRobin is free until your first 10 booked jobs, no card up front. Start free or see pricing.

Sources

Figures from outside CrewRobin were checked against these pages in October 2026. Most industry benchmarks come from vendors and agencies, so treat them as ranges, not rules.

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