How to Calculate Roof Square Footage From Google Earth and Maps
Learn the fastest method to calculate roof square footage from images using Google Earth and satellite maps by address, without ever leaving your desk.
Dragging a dirty tape measure through your landscaping while dodging thorny bushes is not anyone's idea of a good weekend. Worse, trying to climb a steep roof just to pull a measurement is actively dangerous.
Contractors avoid this entirely. They use expensive enterprise software like RoofSnap to pull measurements via satellite, which makes you feel outgunned when evaluating their massive estimates.
But here is the reality: you do not need to pay monthly fees or climb a ladder. You can act as your own free satellite estimator using Google Earth. By using the free measurement tools built into satellite maps, you can get a highly accurate footprint estimate in less than two minutes. Let's do the math.
- Raw Roof Area (no waste)
- 1,503 sq ft
- Total Area (with 10% waste)
- 1,653 sq ft
- Roofing Squares
- 17 squares
- Shingle Bundles
- 51 bundles (3 per square)
- Underlayment Rolls
- 5 rolls (~400 sq ft each)
- Ridge Cap
- 2 bundles / 42 lin ft
- Starter Strip
- 84 lin ft
- Drip Edge
- 15 sticks (148 lin ft)
- Roofing Nails
- ~33 lbs (~5,916 nails)
- Slope Factor
- 1.118
- Pitch Angle
- 26.6°
- Base Footprint
- 1,344 sq ft
Enter your values and press Calculate to see your result.
The Free Satellite Method
When people search for a "roof square footage calculator by address" or "roof square footage calculator google maps," they usually hit a paywall. But Google Earth's built-in polygon tool gives you the exact same geometric data for free.
While Google Maps provides a similar satellite view, the desktop version of Google Earth is far superior for drawing crisp, accurate lines.
Here is exactly how to pull your numbers from space.
Step-by-Step Google Earth Measurement
Quick Reference Guide
| Step | Action | Critical Detail |
|---|---|---|
| 1. Setup | Open Google Earth | Use the desktop or web version, not Google Maps. |
| 2. Locate | Search Address | Zoom in until the house fills the screen. |
| 3. Align | Switch to 2D Top-Down | Crucial: Do not measure in 3D angled view! |
| 4. Tool | Select Ruler Tool | Choose the Polygon/Area option. |
| 5. Trace | Click Roof Corners | Outline the extreme outer edge (includes overhangs). |
Because you are clicking on the edge of the roof as seen from space, you are already including the overhangs.
Applying the Pitch to Satellite Data
Once Google Earth tells you that your flat roof area is, for example, 1,500 square feet, you have completed the hard part.
Now, you just need to apply the pitch multiplier.
- Find your pitch: Go outside and look at your gable end from the ground, or use a smartphone level app in your attic against a rafter. Let's say it is a 6/12 pitch.
- Use the multiplier: A 6/12 pitch has a slope factor of 1.118.
- Do the math: Multiply the Google Earth area by the multiplier. 1,500 × 1.118 = 1,677 sq ft.
Add your standard 10% waste factor (1,677 × 1.10 = 1,844 sq ft), and you now know exactly how much material to order without ever pulling a tape measure out of your toolbox.
Use our Roof Square Footage Calculator at the top of this page to quickly run your Google Earth numbers through the slope multiplier. It is the absolute easiest way to double-check any contractor's estimate.
Ready to run the numbers?
Get your result instantly — private, in your browser.