A roofing estimate starts with an accurate measurement in squares (100 square feet of roof surface each), adjusted for pitch and waste. From there you list every material, not just the shingles, add labor for tear-off and install, disposal, permits and a decking allowance, and price the total so it covers your overhead and profit. Most roofing estimates that lose money got one of those adjustments wrong, not the shingle price.
This guide walks through a shingle replacement estimate step by step, with the math shown so you can check your own.
How do you measure a roof for an estimate?
You need the roof's actual surface area, not the house's footprint. There are three common ways to get it:
- Measure on the roof. Measure each plane's length and width, then add them up. Accurate, but slow and only safe on walkable roofs.
- Measure from the ground and apply pitch. Measure the footprint including overhangs, then multiply by a pitch factor (see below).
- Aerial measurement reports or satellite tools. Fast, and good for planning. Verify on site before you finalize, especially on complex roofs or where trees hide the edges.
Then convert to squares. One square is 100 square feet of roof surface. A roof with 2,600 square feet of surface is 26 squares.
How does roof pitch change the measurement?
A steeper roof has more surface area than its footprint. The pitch factor converts footprint area to actual surface area. It comes straight from geometry: the factor is the square root of (1 + (rise ÷ 12) squared).
Some common factors, rounded:
- 4/12 pitch: about 1.054
- 6/12 pitch: about 1.118
- 8/12 pitch: about 1.202
- 10/12 pitch: about 1.302
- 12/12 pitch: about 1.414
Example: a footprint, including overhangs, of 2,200 square feet on a 6/12 roof is 2,200 × 1.118 = about 2,460 square feet of surface, or 24.6 squares.
Pitch also changes labor. Steep roofs need more safety equipment, more staging and slower work, so many roofers add a steep-roof labor charge above a certain pitch. Same for second- and third-story roofs.
How much waste should you add?
You'll always buy more shingles than the measured area, because of cuts at valleys, hips, rakes and around penetrations. Waste depends on the roof's shape:
- A simple gable roof has relatively little waste
- Hip roofs, multiple valleys, dormers and lots of short runs have more
Many roofers use a lower waste percentage for simple gables and a higher one for complex hip roofs. Rather than adopting a number from someone else, compare what you ordered against what you actually used on your last several jobs. Your own waste figures, by roof type, are the ones to trust.
Continuing the example: 24.6 squares with 12 percent waste = 27.6, rounded up to 28 squares of shingles to order.
What goes on the materials list?
Shingles are the biggest line, but far from the only one. A complete shingle replacement list usually includes:
- Shingles, by the square. Many common shingles are packaged three bundles to a square, but check the manufacturer's coverage for the product you use.
- Starter strip along eaves and rakes, by linear foot
- Hip and ridge cap, by linear foot of hips and ridges
- Underlayment, synthetic or felt, by the square
- Ice and water shield at eaves, valleys and penetrations, where code or the manufacturer requires it. Requirements vary by climate and local code.
- Drip edge, by linear foot of eaves and rakes
- Flashing: step flashing, counter flashing, pipe boots, chimney flashing
- Ventilation: ridge vent, box vents or other vents to meet ventilation requirements
- Fasteners: coil nails, cap nails, and sealant
- Decking allowance: replacement sheets of plywood or OSB, priced per sheet
Measure linear footage for eaves, rakes, hips, ridges and valleys separately. Those numbers drive several lines.
Also check the shingle manufacturer's installation requirements. Many warranties depend on using specific components and installation methods.
How do you price labor, tear-off and disposal?
Labor
Many roofing companies pay installation crews by the square, while others pay hourly. Either way, price your labor from what it actually costs you per square, including payroll taxes, workers' comp and insurance, which can be significant in roofing. Add for:
- Steep pitch and multiple stories
- Extra layers to tear off
- Complex details: chimneys, skylights, walls, crickets
- Difficult access: tight lots, landscaping to protect, long carries
Tear-off and disposal
Tear-off is priced per square per layer. A second layer of shingles doubles the debris and adds labor. Disposal costs depend on the weight of debris and your local dumpster or landfill rates. Asphalt shingles are heavy, so a roof's worth of tear-off can be several tons. If you rent dumpsters, use your real rental and overweight costs per job, not a guess.
Decking
You often can't see the decking's condition until the old roof is off. The common approach is to include a set number of replacement sheets in the price, then a per-sheet price for anything beyond that, written clearly in the contract.
How do you add overhead and profit to a roofing job?
Once you have the full job cost, add overhead and profit as a share of the price, not as a simple markup on cost. If your overhead runs 20 percent of revenue and you want 10 percent net profit, job costs must be 70 percent of the price:
Price = job cost ÷ 0.70
Worked example (made-up numbers for illustration):
- Materials, including 28 squares of shingles and all accessories: $6,200
- Labor, tear-off and install, one layer, 6/12 pitch: $5,400
- Disposal: $650
- Permit: $250
- Decking allowance, 4 sheets: $300
- Job cost: $12,800
- Price: $12,800 ÷ 0.70 = $18,286, rounded to $18,300
If you'd simply added 30 percent to cost, you'd get $16,640. That's more than $1,600 less than the price that actually delivers a 10 percent profit after overhead. For more on why, see markup vs. margin.
Your numbers will be different. The method is what matters.
Should you offer options on a roof?
Yes. Homeowners often welcome a choice. A common way is good, better and best:
- Good: standard architectural shingle, code-required components, standard manufacturer coverage
- Better: upgraded underlayment, ice and water shield in more areas, better ventilation, an enhanced warranty if your manufacturer program offers one
- Best: a premium shingle line and the most complete system you install
Explain in plain terms what each step up gets them. Roofs are a large purchase, and some homeowners will want to pay over time, so our guide to customer financing may help.
What about insurance claims?
Storm work brings its own rules. A few general points:
- Your estimate should reflect the actual work, and you should be careful about representing a homeowner in their insurance claim. Many states regulate this, and in some it requires a public adjuster license.
- Some states make it illegal for a contractor to waive or absorb a homeowner's insurance deductible.
- Some states also have specific contract and cancellation requirements for storm-related roofing contracts.
Rules vary a lot by state, so check with your state licensing board or an attorney before taking on claim work.
FAQ
How accurate are aerial roof measurements? They are widely used and often close, but trees, shadows and complex rooflines can throw them off. Use them to plan, and verify on site before you order materials.
Should I include gutters in the roofing estimate? If you do gutters, quote them as a separate line or option, so the customer can see the roof price on its own.
How long should a roofing quote be valid? Material prices change, so many roofers set a short expiry, like 30 days, and say that prices may need updating after that.
How do I handle rotten decking found during tear-off? State your decking allowance and per-sheet price in the contract, photograph the damaged areas, and tell the homeowner before the job is finished.
How ServFlo helps
ServFlo lets roofers keep shingles, accessories and labor in a pricebook with costs, and build quotes with good, better and best options that homeowners approve online, with a deposit collected on approval. Photos from the inspection attach to the job, and customers can pay by card, bank, or over time with financing if you turn it on. On the Pro plan, job costing compares each roof's actual labor, materials and expenses with the price. See ServFlo for roofing companies and payments.
Photo by Raze Solar on Unsplash.