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Guide · Roof measurement

Roof square footage report: what it contains, how it is calculated, what it costs

Updated · Rotomal

A roof square footage report gives the area of the roof surface, not the house footprint, usually also in roofing squares of 100 sq ft, with the pitch and facets the figure is based on. Roof area equals the footprint (including overhangs) times the pitch factor: a 1,500 sq ft footprint under a 6/12 roof is about 1,677 sq ft, or 16.8 squares before waste. On 29 October 2026, paid reports listed from about $7 to $87 depending on vendor and roof size, and free tracing tools exist if you draw the outline yourself.

What the report contains

  • Total roof surface area in square feet.
  • The same area in roofing squares (area ÷ 100).
  • Pitch of each facet, as rise in inches per 12 inches of run, and the dominant pitch.
  • Number of facets, the main sign of complexity.
  • A suggested waste factor, higher for roofs with many hips and valleys.
  • The date and source of the imagery used.
  • Premium reports add lengths of ridges, hips, valleys, eaves and rakes for ordering trim and flashing.

The method: from footprint to roof area

A sloped roof has more surface than the ground it covers. Measure the footprint including the eaves overhang, find the pitch, multiply by the pitch factor, then divide by 100 for squares and add waste. The pitch factor works for every plane at that pitch, hips and valleys included.

  • Roof area = footprint area × pitch factor
  • Pitch factor = √(1 + (rise ÷ 12)²)
  • Squares = roof area ÷ 100
  • Squares to order = squares × (1 + waste factor)
PitchAnglePitch factor1,500 sq ft footprint becomes
3/1214.0°1.0311,546 sq ft
4/1218.4°1.0541,581 sq ft
5/1222.6°1.0831,625 sq ft
6/1226.6°1.1181,677 sq ft
7/1230.3°1.1581,737 sq ft
8/1233.7°1.2021,803 sq ft
9/1236.9°1.2501,875 sq ft
10/1239.8°1.3021,953 sq ft
12/1245.0°1.4142,121 sq ft

Worked example: 1,500 sq ft footprint at 6/12 is 1,500 × 1.118 = 1,677 sq ft of roof, or 16.77 squares. With 10% waste, 16.77 × 1.10 = 18.4 squares to order. Tools that report pitch in degrees, such as Google's Solar API, convert with rise = 12 × tan(angle).

Report prices

Prices as listed on each vendor's page, checked 29 October 2026, in US dollars per residential report.

ProviderListed priceFree reports or trial
Roof ManagerAbout $7 (billed as $10 CAD)2 free reports
RoofSnap$13 per pay-as-you-go order7-day free trial, no card; first order free offer
Roofr$19 on the free plan; $13 on paid plansNone listed
EagleView Bid Perfect$18Not listed
EagleView Premium$32.75 (20 sq), $60 (40 sq), $87 (40+ sq) at Bronze; from $24.25 at GoldNot listed
Hover (roof only)$29, $49 or $69 by complexityFirst 3 projects free
ExactSquares$40 a month, unlimited7-day trial, card required
RoofStructFree DIY tracing; done-for-you from $14Unlimited DIY tracing on the free plan
Roof Tally$6 per report, or $39 a month for 100None; lookups with no usable roof data are not charged

Free route 1: trace the roof yourself

MapScaping's free roof area calculator needs no account: search the address, trace the roof with the polygon tool on satellite imagery, and enter the pitch in degrees. It returns the footprint, surface area, total with waste, perimeter and squares, and exports a PDF. Its FAQ says satellite measurements are typically within 2–5% for standard residential roofs, and that accuracy depends on how carefully you trace and on the imagery resolution.

RoofStruct's free plan offers unlimited do-it-yourself tracing on satellite imagery or your own drone photos, with PDF exports that carry RoofStruct branding. Estimates and material orders need its $69-a-month Pro plan.

Free route 2: Google's Solar API data

If you can make an API call, Google's Solar API returns, for the building nearest a coordinate, the whole-roof area and ground area, and for each roof segment its area, pitch in degrees and azimuth. It also returns the imagery date and a quality grade (HIGH, MEDIUM or BASE), and answers with a 404 error where no imagery meets the quality you request. Areas come in square meters; multiply by 10.764 for square feet.

Building Insights requests are free for the first 10,000 a month, then $10 per 1,000. You need a Google Cloud project and an API key, and Google says some Solar API content is no longer returned for billing addresses in the European Economic Area.

https://solar.googleapis.com/v1/buildingInsights:findClosest?location.latitude=37.4450&location.longitude=-122.1390&requiredQuality=HIGH&key=YOUR_API_KEY

When a paid report is worth it

Free tracing is fine for one roof. Use a premium report with edge lengths for insurance work and before ordering material. For ten or a hundred addresses, or when the homeowner should get a document with your prices on it, Roof Tally fetches the Solar API data per address, converts it to square feet and squares with a stated range, and applies your price per square to a branded PDF, from $6 a report.

Questions

How do I get roof square footage from house square footage?

Start from the roof footprint including overhangs, not the living area; a two-storey house has a smaller roof footprint than its floor area. Multiply the footprint by the pitch factor, for example 1.118 for a 6/12 roof.

How many squares is a 2,000 sq ft roof?

20 squares, since one square is 100 sq ft of roof surface. With a 10% waste factor you would order 22 squares.

Is Google's Solar API free?

Building Insights requests are free for the first 10,000 a month, then $10 per 1,000; Data Layers requests are free for the first 1,000, then $75 per 1,000 (Google's pricing page, checked 29 October 2026).

How accurate are satellite roof measurements?

MapScaping and ExactSquares both say typically within 2–5% for standard residential roofs. Tree cover, complex roofs and old imagery lower accuracy, so measure on site before ordering material.

Sources

Guides and answers