Measure the footprint
Enter building length and width, or skip to a roof surface area you already measured.
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Roofing Calculator
Estimate roof area, roofing squares, waste allowance, and shingle bundles from a few simple measurements.
- Footprint or known area
- Waste and bundle rounding
- Materials only — not a replacement quote
Estimate roof area and bundles
Start with the house footprint. Results update as you type.
Measurements stay in your browser
From footprint to bundles
The math stays visible, so you can see what changed the estimate.
Apply the roof pitch
The pitch multiplier converts the horizontal footprint into sloped roof area. Get the pitch from the pitch calculator if you need it.
Add waste and round up
Waste is added before converting area into squares. Bundles always round up to a whole package.
Roofing calculator FAQ
These answers cover the assumptions that most often create bad material estimates.
What is one roofing square?
One roofing square equals 100 square feet of roof surface. A 1,500-square-foot roof is 15 squares before waste.
How much waste should I add?
Ten percent is a common starting point for a simple gable roof. Hips, valleys, dormers, and many cuts usually need more. Confirm the allowance with the installer or supplier.
How many bundles are in a roofing square?
Many asphalt shingle products cover about 33.3 square feet per bundle, or three bundles per square. Coverage varies by product, so this calculator lets you edit coverage per bundle.
Does this calculate full roof replacement cost?
No. If you enter a price per bundle, the subtotal is materials only. It excludes labor, tear-off, underlayment, flashing, ventilation, permits, disposal, delivery, taxes, and repairs.
Should I measure the building footprint or the roof surface?
Use footprint plus pitch when you can measure the building from the ground. Use known roof area when you already have the sloped surface area. Do not multiply a sloped area by the pitch multiplier again.