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How to Measure a Roof

A step-by-step guide to measuring a roof’s square footage and pitch so you can estimate shingle quantity, roof replacement cost, and more. All from the ground -- no ladder required.

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Reliable roof measurements make projects go smoothly and stay on budget. Whether you’re a contractor training a new employee or a homeowner budgeting for a new roof, use this guide to accurately measure and calculate roof squares for any roof.

STEP 1

Measure roof square footage

First, you’ll need to determine the roof’s total square footage

Measure the length and width of each roof surface (include dormers), record on a sketch of the roof
Note number of chimneys, skylights or other obstructions
Multiply length by width for the square footage of each surface (if a triangle, divide by 2)
Add up the square footage for each surface to get the total square footage of your roof

Step 2

Determine roof pitch factor

A steeper roof needs more materials. Pitch measures roof steepness, boosting measurement accuracy.

Measure the number of inches the roof rises vertically every 12 inches of horizontal roof length (use a pitch app or ruler/level method)
Record as a fraction with rise over run (ex. 4/12); the larger the rise, the steeper the roof
Use an online roof pitch multiplier chart to determine the roof’s pitch factor (a pitch of 4/12 has a pitch factor of 1.054)

Step 3

Calculate Roof Squares

A roof square is a 10 x 10 area equal to 100 square feet of roof surface. To calculate:

Multiply total roof square footage (Step 1) by the roof’s pitch factor (Step 2). Example: 2,134.0 ft² x 1.054 = 2,249.24 ft²
Divide total square footage by 100. Example: 2,249.24 ft² / 100 = 22.4924, or 22.5 roof squares
Use the number of roof squares needed to price materials

HOVER Roofing & Siding Measurements

The HOVER app keeps you off the roof and saves time. HOVER uses smartphone photos of any home to build an interactive 3D model with accurate exterior measurements (roof, siding, trim, etc.)

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Roofing Materials

The purpose of calculating the precise measurements of a roof is to ensure you order the appropriate amount of roofing materials – whether it’s for a shingle, metal, and any other type of roof. Here are common roofing materials and considerations.

Shingles

Shingles are sold in bundles. Depending on type and brand, it may take a different number of bundles to make a roof square. When comparing shingle cost, remember to base price on squares and not on bundles.

Metal Roofing

Metal roofing is great for homes in snowy regions. It’s typically sold by the sheet or panel. To determine the number of sheets or panels neeeded to cover the roof, divide the width of the roof by the sheet or panel width.

Other Roofing Meterials

The basic roof square calculations detailed above will help estimate cost for other materials. Be sure to include the cost of leak barriers, deck protection, drip edge, rake edge, ridge vents, hip and ridge caps, etc.

Frequently Asked Questions

Why is it important to get accurate roof measurements?

Is there an alternative to manually measuring my roof?

Why should I use Hover to measure my roof?

What are some other benefits of using Hover?

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