What it calculates
Estimate roof area, squares and bundles.
Roofing Calculator
Estimate roof area, roofing squares and shingle bundles from footprint and pitch factor.
Planning and estimating aid only. Verify project requirements, manufacturer instructions, adopted codes, permits, and field conditions before performing regulated work.
Construction estimating
How to Use This Calculator
Use the field units shown below, then compare your result with the worked example. Use a pitch factor appropriate to the measured roof geometry.
How the calculation works
Footprint area is multiplied by the entered pitch/complexity factor and waste, then divided by 100 for roofing squares.
What the result means
Use measured roof-plane area when available; hips, valleys and complex roofs generally increase waste.
Apply pitch and waste before counting bundles
A 1,000-square-foot footprint multiplied by a pitch factor of 1.12 gives 1,120 square feet of slope-adjusted area. With 10% waste it becomes 1,232 square feet, or 12.32 roofing squares. At the assumed 3 bundles per square, round 36.96 up to 37 bundles.
Contractor tip: Use a pitch factor appropriate to the measured roof geometry. Do not apply the slope factor again if you entered an already slope-adjusted area. Valleys and complex cuts can change waste.
Verify the final quantity
The bundle estimate assumes 3 bundles cover one square. Read the actual product coverage. Hip and ridge material, underlayment, flashing and starter strips are not separately counted here.
Good practice: Compare the calculated quantity with plans, specifications, product packaging and current field conditions before purchasing material.