How to estimate a roofing job by the square, start to finish
Roofing is estimated in squares, where one square is 100 square feet of roof surface: measure the roof, add a pitch factor, order materials with about 10 percent waste, price tear-off and install labor per square, add disposal, and divide the whole cost by one minus your target margin. On an architectural shingle reroof that math usually lands between $450 and $650 per square installed. The estimate is won or lost on the waste factor and the tear-off assumptions, not the shingle price.
Step by step
- Measure the roof and convert to squares. Measure the footprint, apply the pitch factor (a 6/12 roof multiplies plan area by about 1.12, a 9/12 by about 1.25), and divide by 100 to get squares. A 2,150 square foot footprint at 6/12 is roughly 24 squares of actual roof surface. Squares are the unit every supplier, crew, and competitor quotes in, so get this number right before anything else.
- Count layers and probe the deck. Find out how many shingle layers are coming off, because a two-layer tear-off is nearly double the labor and disposal weight of one. Walk the roof and feel for soft decking, then carry a per-sheet unit price for replacement, with OSB at about $1.05 a square foot. Decking is the classic hidden cost, so price it as a stated allowance rather than a hope.
- Take off every linear and count item. Beyond field shingles, measure eaves and rakes for drip edge at about $1.65 a foot, valleys for flashing at $4.60 a foot, ridges for cap at $4.35 and vent at $3.85 a foot, and count penetrations for pipe boots at $15 each. Chimneys get a flashing kit near $96. These lines routinely add $800 to $1,500 that a beginner's square-footage-only estimate misses.
- Apply the waste factor honestly. Simple gable roofs waste about 10 percent of field shingles to cuts and starters; hips, valleys, and dormers push waste to 15 percent or more. On architectural shingles at about $138 a square, an ignored waste factor on a 24 square roof is a $300 to $500 hole. Order to the waste-adjusted number and price to it too.
- Price labor per square by pitch and complexity. Crews think in squares per day: a four man crew commonly tears off and lays back 20 to 30 squares of walkable roof in a long day, while steep or cut-up roofs cut that in half. Convert to crew-hours times a loaded rate covering wages, burden, workers comp (which is brutal in roofing), and equipment. Steep-slope premiums of 20 to 40 percent on labor are normal and should be visible in your pricing.
- Add disposal, underlayment, and code items. A 24 square single-layer tear-off is roughly 3 to 4 tons of debris, so price the dumpster, commonly $400 to $600. Synthetic underlayment at $19 a square goes over the whole deck, and cold-region codes require ice and water shield at the eaves, about $1.85 a linear foot, typically two courses past the warm wall line. Include the roofing permit where your jurisdiction requires one.
- Divide by margin to set the price. Materials plus labor plus disposal plus permit is your cost; the quote is that cost divided by one minus the margin you are targeting. At 35 percent margin, an $8,841 cost divides by 0.65 to about $13,600. Roofers who instead add 35 percent on top are actually running a 26 percent margin, and in a trade with roofing's insurance costs that gap is the difference between growing and folding.
- Write the allowances and send it before you drive off. State the decking allowance per sheet, the layer assumption, and what happens if a third layer or rot appears. Exclude gutters, skylight replacement (a new skylight runs about $435 in materials), and interior repairs unless you priced them. Then send a line-item estimate the homeowner can e-sign the same day, because storm-season roof decisions move fast and the first credible number anchors the rest.
The roofing pricing formula
(Squares times 1.10 waste times shingle cost) plus underlayment, edge metal, flashing, and vent lines equals materials; add crew-hours times your loaded rate, the dumpster, and the permit for total cost; the quote is cost divided by (1 minus margin). To hit 35 percent margin, divide by 0.65. Note the trap: a 35 percent markup on cost yields only about a 26 percent margin because the markup percentage is figured on cost while margin is figured on the final price.
A 24 square architectural reroof: 27 squares of shingles after 10 percent waste and rounding up, at $138 a square, is $3,726; 25 squares of synthetic underlayment at $19 is $475; 180 feet of drip edge at $1.65 is $297; 150 feet of ice and water shield at $1.85 is $277.50; 40 feet of ridge cap at $4.35 plus 40 feet of ridge vent at $3.85 is $328; four pipe boots at $15 is $60; and 50 pounds of nails at $2.15 is $107.50. Materials come to $5,271. A four man crew handles tear-off and install in about 48 crew-hours, which at a $65 loaded rate is $3,120, and the dumpster runs $450, putting cost at $8,841. Divide by 0.65 for a 35 percent margin and you get $13,602, so you quote $13,600, about $567 a square.
Cost factors roofers price for
Pitch and walkability
Anything over 7/12 slows production, requires more staging and harness work, and raises the labor line 20 to 40 percent. Above 10/12, some crews charge half again their base rate. Pitch also raises the true surface area through the pitch factor, so it hits materials and labor twice.
Tear-off layers
A second layer roughly doubles tear-off time and adds tons to disposal. Codes in most U.S. jurisdictions cap roofs at two layers, so a two-layer roof has no overlay option and must come off. Verify layers at the estimate, not on day one.
Cut-up complexity
Hips, valleys, dormers, and dead valleys multiply flashing linear feet, raise the waste factor toward 15 percent, and slow the crew. Two roofs with identical square counts can differ 30 percent in cost from complexity alone. Count facets, not just squares.
Deck condition
Rotted OSB or plank decking gaps too wide for modern shingles turn into carpentry mid-job. Carry a written per-sheet replacement price around $70 to $90 installed and an inspection note in the contract. The allowance protects both sides and speeds the yes.
Access and staging
A ranch with driveway access loads from the truck; a three-story rear slope over a sunroom needs equipment, longer carries, and protection for landscaping below. Material staging and cleanup time are real crew-hours. Look at the property, not just the roof.
Season and storm cycles
Post-storm demand spikes labor and shingle prices and stretches supplier lead times. Winter installs slow production and constrain adhesive sealing temperatures. Price to current local conditions, and date-limit your estimate to 30 days so a price move does not strand you.
Frequently asked questions
How many squares is my roof if the house is 2,000 square feet?
Footprint is not roof area: multiply the footprint by a pitch factor, roughly 1.12 for a 6/12 roof and 1.25 for a 9/12, then add overhangs. A 2,000 square foot single-story footprint at 6/12 with typical overhangs is usually 23 to 26 squares. Two-story homes have smaller footprints per living area, so their roofs are often smaller than buyers expect.
What is a fair markup on a roofing job?
Roofing carries some of the highest overhead in the trades, with workers comp rates that can run 20 to 40 percent of payroll plus equipment, so healthy roofing companies price at a 30 to 40 percent gross margin, dividing cost by 0.60 to 0.70. A 10 percent markup does not even cover the comp premium on the labor it is marking up. If your price only beats competitors because your margin is thinner, you are financing your customers' roofs.
Should tear-off be its own line item?
Yes, with the layer count stated, because tear-off labor and disposal scale with layers while install labor does not. Separating it also makes the decking allowance and any second-layer surprise easy to handle as a documented change instead of an argument. Most professional bids show tear-off, install, and disposal separately.
How much waste should I add for shingles?
Plan on 10 percent for straightforward gable roofs and 15 percent or more for hips, valleys, and dormers, since caps and starters consume field shingles too unless you buy dedicated starter at about $1.35 a foot and cap at $4.35 a foot. Waste is not inefficiency; it is geometry. Bidding at zero waste means the last two squares of the roof come out of your profit.
Is there software that prices a roof while I am still on it?
Staxen's Eddie builds the estimate by voice: read off your squares, pitch, and flashing counts from the roof and Eddie drafts priced line items you review and send as a text the homeowner can e-sign immediately. Eddie costs $59 per month and your first job is free with no card required. Staxen does not do satellite roof measurement, so the tape measure part is still yours.
Start free with Staxen: your first job is on us, no card required.