How to Charge a Roofing Job by the Square Foot

Whether you're a roofing contractor or merely a homeowner who happens to be having her roof replaced, it's important to know and understand how to charge for a roofing job using measurements in square feet. Before charging for a roof job, roofers generally inspect the roof. During this inspection, roofers will measure the roof, determine how many layers of shingles need to be removed and determine whether there is damage to the decking (plywood) under the shingles and tar paper.

Roofing job costs are usually determined by the square footage of a roof.
  1. Place your ladder into position and climb on to the roof.

  2. Measure the length and height of the roof in feet.

  3. Multiply the length of the roof times the height. The product of this measurement will give you the total square footage of the roof.

  4. Divide the total square footage of the roof by 100 to estimate the number of "roofing squares" needed. A single "square" is equal to three bundles of roofing shingles. Round up to the higher number if the number of squares is a fraction. For example, four-and-a-half squares would be rounded up to five squares. This ensures that you will have enough shingles to cover the roof.

  5. Multiply the number of squares by three. This figure will give you the exact number of bundles of shingles you will need for the job. Average bundles of shingles are approximately $25 to $30. Multiply the number of total bundles you will need by $30. This will give you the total cost for shingles for the roofing job.


  • A roofing job is only partly determined by the square footage. Other factors, like labor, cost for replacing decking and hauling the trash away are also factored in by the roofing contractor.
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