How to Measure a Roof

Are you thinking about getting new roofing? Do you have plans to renovate your house? How about a genuine interest in how big that roof is on the top of your home?

If you answered ‘yes’ to any of these questions, you’ve come to the right place. You need to learn how to measure a roof, and we’re here to explain how. Just keep reading.

How to Measure a Roof From the Ground

First, you have to measure the length and width of the building’s exterior walls using a measuring tape.

If your roof hangs over the sides of the building, try your best to measure how far the overhang is. It may be best to do this in the middle of the day when the sun is directly above your building. In these conditions, you may get a reliable estimate by measuring the shadow.

Next, you need to calculate the pitch (steepness/slope) of the roof.

Set up a ladder and bring your level with you. Once you’re at the level of the rooftop, place the level lengthwise with the roof’s slope and angle it so that the bubble is centered. Then, measure the distance from the end of the level to the surface of the roof.

With the level, you’re mimicking the triangular shape that the roof has. Rather than measuring the angle of the large triangle (the roof), you’re measuring the angle of the small triangle (the level).

After you collect these measurements, you should use a pitch multiplier table to find the multiplier that matches the pitch you measured. Once you find this, multiply the pitch multiplier by the roof’s square footage (length x width that you collected earlier).

To estimate the number of materials you need, divide the final number by 100. Since shingles come in bundles to cover 100 square feet, we divide by 100 to see how many squares you may need. Although, you should always get a little more than you calculate in case something goes wrong.

How to Measure a Roof by Diagramming

To diagram the roof, you’ll need to find a safe way up to get accurate measurements.

If you feel unsafe performing these measurements yourself, you should consider hiring experts like those at

After you’re safely on the roof, measure the length and width of the main section of the roof. Then, measure any additional roofing structures separately.

After writing these calculations down, you can draw a diagram of your roof and label the measurements you collected. Then, break your drawing down into simple geometric shapes like triangles and squares.

For each shape, calculate the area and record your results. Add up all of the areas that you get from your shapes to get the total square footage of the roof.

Then, divide by 100 to get an estimate for the number of materials you’ll need.

Beyond Measuring a Roof

You did it! You know how to measure a roof.

Whether you decide to measure from the roof or the ground, make sure that you’re staying safe. When in doubt, hire a professional.

And, check out our blog for more need-to-know information like this.

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