How to Calculate Roofing Squares

A roofing square is a unit equal to 100 square feet of roof area. Start with the roof area in square feet, then divide by 100.

How to calculate it

1. Estimate or measure the roof surface area.
2. Use the actual roof surface area rather than the footprint of the building.
3. Divide the square-foot area by 100.
4. Add the material allowance required for cuts, overlaps and the specific roofing product.

Formula

Roofing squares = roof area in square feet ÷ 100.

Example

A roof area of 2,400 square feet equals 24 roofing squares before any additional material allowance.

Important notes

• Roof geometry can make the surface area larger than the building footprint.
• Different roofing products have different coverage and waste requirements.
• Use manufacturer installation instructions and local requirements when converting squares into purchased materials.

Before ordering materials

Use measurements from the actual project whenever possible and keep all dimensions in compatible units. Material coverage, yield, density, package size, waste, compaction, cuts, overlaps, and site conditions can affect the quantity that must be purchased.

The calculation on this page is intended as a transparent estimating method. Compare the result with manufacturer instructions, supplier ordering units, project drawings, and applicable local requirements before placing an order.

Use the How to Calculate Roofing Squares calculator

This page provides a practical estimating method. Verify project specifications, local requirements and manufacturer instructions before purchasing materials.