Roofing squares explained
A roofing square equals 100 square feet of roof surface—not 100 square feet of floor area.
Reviewed August 2026 · HomeCostPilot Editorial Team
Convert roof area to squares
Add the surface area of every roof plane, then divide by 100. A measured 2,000-square-foot roof contains 20 roofing squares before ordering allowances. GAF uses the same 100-square-foot definition.
Why the house footprint is not enough
Pitch makes roof surface larger than the horizontal footprint. Overhangs, dormers, additions and intersecting planes also change the measurement. Do not climb a roof without appropriate training and fall protection; professional aerial or onsite measurement is safer.
Squares are not the final order
Starter courses, hips, ridges, valleys, penetrations and cuts create additional material needs. Bundle coverage varies by product, so convert squares to packages using the selected manufacturer instructions rather than a universal bundle assumption.
Cost factors beyond area
- Pitch, stories and staging
- Number of tear-off layers
- Decking repairs
- Flashing and ventilation
- Disposal access and weight
- Material system and warranty scope
Source: GAF roofing-square guide.