# How to Calculate a Roofing Square

Roofing shingles sell by the square.
One square of roofing material is equal to 100 square feet, or a perfect square shape that is 10-by-10. Roofing shingles are individually packaged in bundles. Each bundle is equal to 33 1/3 square feet. Three bundles of shingles is equal to one square of roofing, or 100 square feet. Calculating your roof’s square area will mean having to climb on the roof.

## Step 1

Set the extension ladder against the side of the home. Follow all safety directions printed on the side of the ladder. Climb the ladder to the roof.

## Step 2

Measure the overall length of the roof with the tape measure.

## Step 3

Run the tape measure from the lower end of the roof up to the middle of the upper peak. This is the width of the roof.

## Step 4

Multiply the length times the width. The result is the square footage of the roof for that area. Perform the same measurements and calculations for all areas of the roof.

## Step 5

Add all of the square footage calculations together. Divide that total by 100 square feet. The result is equal to the number of squares required to cover the roof.

## Step 6

Divide the number of squares by three. The result is the total number of shingle bundles that is needed for covering the roof.