Roof size report · Method
How we measure roof size — RuufPro roof size report
This page explains exactly where our roof size numbers come from, what counts as a "building" in a city, and what these numbers can't tell you. See the full table on the roof size report.
Last updated 2026-09-06.
Where the data comes from
Microsoft GlobalMLBuildingFootprints (github.com/microsoft/GlobalMLBuildingFootprints), CDLA Permissive 2.0.
This dataset draws a shape (a "footprint") around every building it can see in satellite and aerial pictures. We use those shapes, not a survey or a tape measure.
How a building is counted for a city
The footprints were drawn by computer vision from satellite and aerial pictures taken between 2014 and 2024, and we cut the whole country into small map tiles so any address can be looked up. (The exact method text is kept, word for word, in this page's machine-readable data.)
We drew a rectangle by hand around each city's built-up area. If the center point of a building's footprint falls inside that rectangle, we count it toward that city. That rectangle is our own estimate of where a city's buildings are — it is not the city's real, official boundary.
The pitch factor
A footprint is a flat, top-down shape. A real roof is tilted, so it has more surface area than the flat footprint underneath it. To account for that, we multiply every footprint's area by 1.083 — a flat estimate for a common 4-in-12 roof pitch (a roof that rises 4 inches for every 12 inches it runs).
Real roofs vary. A steeper roof has more surface area than this estimate; a flatter roof has less. This number is meant to be a reasonable middle ground, not a measurement of any one roof.
What these numbers are not
- Not an official city boundary. The area we measure is a hand-drawn rectangle, not a city limit line.
- Not a quote. Nothing on the roof size report has a dollar figure. For a price, use the instant quote tool on any city page.
- Not a measurement of your specific roof. These are medians and ranges across many buildings, not a look at any one address.
At a glance
- Data as of
- 2026-09-06
- Pitch factor
- 1.083 (flat 4-in-12 pitch estimate)
- License
- CDLA Permissive 2.0
See the numbers
Read the full roof size report for every city, or jump to one state's cost pages:
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