How to Measure Roof with Google Earth

This guide shows you how to use Google Earth to get a rough measurement of your roof’s area and dimensions. You’ll use the built-in ruler tool to trace the outline of your roof from satellite imagery, then calculate the area. You’ll need a computer with Google Earth Pro (free) or the web version, and a clear satellite view of your house.

What You’ll Need

• A computer with internet access
• Google Earth Pro (free download) or the web version (earth.google.com)
• Your address or the location of the roof you want to measure
• A mouse or trackpad (easier than touch)

Step-by-Step

1. Open Google Earth. If you have Google Earth Pro, launch it. Otherwise, go to earth.google.com in your browser and click “Launch Earth.”
2. Find your roof. In the search box (top left), type your address or the name of the building and press Enter. The map will fly to that location. Zoom in until the roof fills most of the screen.
3. Adjust the view for best visibility. Ensure you’re looking straight down (top-down view). In Google Earth Pro, press r on your keyboard to reset the view. In the web version, use the compass or press the “N” button to orient north and then tilt to 0° using the controls.
4. Open the ruler tool. In Google Earth Pro, click the ruler icon in the toolbar (or go to Tools > Ruler). In the web version, click the ruler icon on the left sidebar.
5. Choose the polygon mode. In the Ruler dialog, select the “Polygon” tab (Google Earth Pro) or click the polygon icon (web). This lets you trace a multi-sided shape.
6. Set the measurement units. In the Ruler dialog, choose “Feet” or “Meters” for length, and “Square Feet” or “Square Meters” for area. You can also use yards or acres if you prefer.
7. Trace the roof outline. Click on one corner of the roof, then click each subsequent corner around the perimeter. Follow the edges of the roof as closely as you can. For a rectangular roof, you’ll click four points. For complex roofs, add more points at each change in direction.
8. Close the shape. Click on the starting point (or double-click) to finish the polygon. The area will appear in the Ruler dialog.
9. Read the measurement. The dialog shows both the perimeter (length) and the area. The area is what you need for roofing materials. Write it down.
10. Repeat for each roof section. If your roof is not a simple rectangle, you’ll need to measure each distinct section separately (e.g., main roof, garage, dormer) and add the areas together.
11. Account for slope (optional but important). The area you measured is the “footprint” (horizontal projection). The actual roof surface is larger because it’s sloped. Multiply the footprint by a slope factor: for a 4/12 pitch (18.4°), multiply by 1.054; for 6/12 (26.6°), multiply by 1.118; for 8/12 (33.7°), multiply by 1.202. If you don’t know the pitch, use 1.15 as a rough average.

Common Mistakes

• Measuring the ground, not the roof. Make sure you’re tracing the roof outline, not the lawn or driveway. Zoom in until you can clearly see the roof edges.
• Forgetting the slope. The Google Earth area is the flat footprint. The actual shingle area is larger. Not multiplying by the slope factor will underestimate the material needed.
• Including overhangs incorrectly. The satellite image shows the roof as it is, including eaves. That’s fine – you want the full roof area. But don’t include shadows or trees that overlap the roof.
• Using the wrong units. If you set the ruler to meters, you’ll get square meters. If you need square feet, switch the units before measuring.
• Not measuring each section separately. A complex roof with valleys and hips cannot be traced as one polygon. Break it into rectangles and triangles.

Tips

• Use the historical imagery tool. In Google Earth Pro, click the clock icon to see older images. Sometimes a clearer image is available from a different date.
• Check the “3D buildings” layer. Turn off the 3D buildings layer (in Layers panel) to get a clean top-down view without 3D models obscuring the roof.
• Use the “Add Path” for irregular shapes. If your roof has curved edges, use the “Path” tool instead of polygon, but you’ll only get length, not area. For area, use polygon with many points.
• Save your measurements. In Google Earth Pro, you can save the polygon as a KML file (File > Save Place As) to keep for reference.
• Double-check with a tape measure. If possible, measure the length and width of the house from the ground to verify your Google Earth numbers.

Troubleshooting

• No satellite image or too blurry. Try zooming out and back in. If the area is still blurry, use the historical imagery tool to find a clearer date. In remote areas, you may need to use a different mapping service.
• Ruler tool not working. In the web version, the ruler icon might be hidden under the “Tools” menu. Refresh the page. In Google Earth Pro, make sure you haven’t accidentally toggled the ruler off.
• Can’t see the roof edges clearly. Shadows can obscure edges. Use the sun/shadow slider (in Google Earth Pro, View > Sun) to change the time of day and reduce shadows.
• Area shows as 0. You haven’t closed the polygon. Double-click on the first point to close it, or click the “Done” button in the ruler dialog.
• Measurements seem too large or too small. Check your units. Also ensure you’re not zoomed out so far that you’re tracing the whole block. Zoom in to roof level.

Frequently Asked Questions

Is Google Earth measurement accurate enough for roofing estimates?

It’s accurate for the footprint (within a few percent), but the slope factor is an estimate. For a final quote, a professional should measure on-site. Use Google Earth for a rough budget.

Can I measure a roof on my phone with Google Earth?

The mobile app has a ruler tool, but it’s harder to use on a small screen. The desktop version is recommended for accuracy.

How do I find the roof pitch to apply the slope factor?

If you don’t know the pitch, you can measure it from the side view in Google Earth (tilt the view) or use a pitch gauge on the roof. Otherwise, use 1.15 as a rough multiplier.

What if my roof has multiple sections?

Measure each section as a separate polygon, then add the areas. For a hip roof, you can measure the rectangle of the main body and the triangles of the hips separately.

Does Google Earth include the thickness of the roof?

No, it measures the outer edge as seen from above. That’s fine for area calculations.

Can I export the measurement to a file?

In Google Earth Pro, you can save the polygon as a KML file and open it in other GIS software. The web version doesn’t allow export of measurements directly.

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