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How the measurement works

Satellite roof data and building outlines

When a homeowner types in their address, we measure their roof from satellite imagery and building-outline data — no one visits the home, and nothing is scanned in person at this step. This gives us a starting area and slope for the roof, which the instant quote tool turns into a price range.

The confirm-your-house step

Before showing a price, we show the homeowner the satellite photo we measured, with the roof outline drawn on top. They confirm it's the right building by clicking "Yes, that's my home." This step exists because addresses can occasionally match the wrong building.

Tap another building

If the outline is wrong, the homeowner can click "No / wrong building" and tap the correct building on the image instead. The tool re-measures from wherever they tapped.

Detached structures

When a separate structure — like a detached garage or shed — shows up near the main house, the homeowner can tell us whether to include it in the measurement.

When imagery is missing

Not every address has usable satellite or outline data. When that happens, the tool doesn't get stuck — it quietly switches to asking the homeowner a few short questions about their home (size, stories, roof shape, garage) instead. A homeowner can also choose "Answer questions instead" at any point during the address step.

How accurate is it?

Every number the tool shows is a ballpark estimate, not a binding quote. Measuring from satellite gets closer than guessing from a homeowner's answers to a few questions — but it's still a starting point, not a final price. The real number is confirmed at a free in-person inspection, where hidden issues like decking damage can be seen up close.

Older or lower-quality satellite imagery for an area makes a measurement less certain, so the tool automatically shows a wider price range in those cases. See Pricing settings for exactly how much wider.

Caching

To avoid re-measuring the same address over and over, we keep a measurement on file for up to 30 days before it's cleared and re-measured fresh.

Data attribution

The tool uses two outside data sources, and gives them credit where it shows their data:

• Satellite roof measurements include data from Google Maps.
• Building outline data © Microsoft (US Building Footprints), ODbL.

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