How to Measure a Roof from Google Earth

Before you trace anything

Google Earth is a product of Google. TrueRoofView is not affiliated with Google. Use the desktop app or the web app, search the address, and switch to a straight-down view. Zoom until the eaves are distinct from the neighbor’s roof and from the driveway.

Look for an imagery date if the app shows one. A reroof, an addition, or a storm can make last year’s outline wrong. Shadows, oak canopy, and a dark shingle against a dark patio all cause the same mistake: you click a shadow and call it an eave.

Trace the outline

Open the measure tool (the ruler). Set units to feet. Click each outside corner of the roof and close the shape. Read the perimeter and the area the tool reports.

That area is plan area: the flat footprint as seen from above. Roofing squares are based on sloped surface area, which is larger on a steeper roof. A garage and a porch often need their own shapes. A single outline around a building with a recessed courtyard will overstate the roof.

• Click eaves, not the drip shadow on the ground
• Leave out the neighbor’s roof on a zero-lot-line house
• Trace dormers only if you can actually see their edges
• Write the number down as a sketch, not as a bid

Why pitch is the missing piece

Surface area is roughly plan area divided by the cosine of the roof angle. A 6/12 pitch is about 26.6 degrees, so the slope factor is higher than 1. You only get to use that conversion if you already know the pitch. A nadir photo does not show rise. Google Earth’s terrain model is far too coarse to measure fascia height on a house.

Hips and valleys make it worse. Two roofs can share a footprint and need different waste, different starter, and different hip-and-ridge cap. The trace will not split those lines. Predominant pitch also fails when one wing is 4/12 and a dormer is 10/12. That is the gap a Premium roof measurement report is for.

When the sketch is enough, and when it is not

A Google Earth outline is reasonable for a homeowner wondering whether a roof is closer to 20 squares or 40, or for checking that you have the right building. It is a poor document to attach to a proposal, a material order, or an estimate in Xactimate.

TrueRoofView’s Bid Report is $16.20 and includes area, predominant pitch, and squares. Premium is $21.83 when you need the edges. Both are aerial estimates too: still verify on site. They are measured for that purpose, with a 30–60 minute delivery clock, instead of a polygon you drew after dinner. What’s in the report lists the fields. We measure United States addresses nationwide, wherever the imagery is clear.

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