When a roofing contractor tells you your home is "28 squares," they're saying the total surface area of your roof — measured along the actual slope, not projected down to the ground — is 2,800 square feet. One roofing square equals 100 square feet of roof surface. This is the fundamental unit by which materials are ordered, labor is priced, and bids are written. Understanding squares lets you cross-check any bid you receive — and you can get a free instant estimate that uses satellite measurement to calculate your square count before you ever talk to a contractor.
The most important thing to know is that roof squares are not the same as your home's square footage. A 2,000-square-foot house might have a 22-square roof or a 35-square roof depending on pitch and overhang. Pitch determines how far the roof surface extends for every foot of horizontal run — the steeper the roof, the more surface area per square foot of floor space.
The Pitch Multiplier
Pitch is expressed as rise over run — a 6:12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. To convert your ground-level footprint measurement to actual roof surface area, you multiply by a pitch factor:
4:12 pitch — multiply footprint by 1.054 6:12 pitch — multiply footprint by 1.118 8:12 pitch — multiply footprint by 1.202 10:12 pitch — multiply footprint by 1.302 12:12 pitch — multiply footprint by 1.414
A 2,000-square-foot footprint on a 6:12 pitch generates 2,236 square feet of roof surface before overhangs. Add 18 inches of overhang on all sides of a 40x50 foot house and you're adding another 360+ square feet. The final number divided by 100 gives you squares — roughly 26 squares in this example.
How Contractors Measure
Modern contractors increasingly use satellite measurement tools — EagleView, Hover, and GAF QuickMeasure are the dominant platforms. These services produce detailed roof reports from aerial imagery and algorithms that extract pitch and plane geometry, returning a measurement accurate to within 3-5% on most residential roofs. The reports cost the contractor $15-40 per address and are far faster and safer than manual measurement.
For complex roofs, drone measurement with photogrammetry provides even higher accuracy — the drone generates a 3D model from which measurements are extracted precisely. Manual measurement (a contractor on the roof with a measuring tape) remains the most accurate method but is rarely used for estimating because of the time investment.
CandelQuote provides satellite-based roof measurement for free, giving homeowners access to the same data contractors use before you ever talk to a contractor.
Waste Factor and What It Means
Roof materials are sold by the square. But a contractor never orders exactly the squares the roof measures — there is always waste. Starter strips, hip and ridge cap, cut shingles at valleys and rakes, and damaged material all contribute to overage. Standard waste factor on a simple gable roof is 10-12%. A hip roof with multiple valleys might run 15-18%. A highly complex roof can run 20%+.
Waste factor inflates the material order, not the roof size quoted. If your roof is 28 squares and the contractor adds 15% waste, he orders materials for 32.2 squares. He should not be charging you for 32 squares of installation — he should be charging for 28 squares of roof with a materials line item that reflects the actual order.
What to Look for in a Contractor Bid
A legitimate roofing bid specifies the number of squares being replaced. It should also list the waste percentage assumed and the resulting material order quantity. If a bid says only "tear off and replace roof: $14,800" with no square count, you have no basis for comparison. Our guide on how much a roof replacement costs shows exactly what a fully itemized bid should include.
If a contractor won't tell you how many squares they measured, that is a red flag. The square count is not proprietary information — it's verifiable through satellite tools. Any contractor who treats it as a state secret is either padding it or doesn't want you to comparison-shop the number.