Roofing Calculator
Free roofing calculator. Enter the building footprint and roof pitch to get roofing squares, shingle bundles, underlayment rolls, nails and ridge cap for asphalt shingle roofs.
About This Free Online Roofing Calculator
Our free roofing calculator estimates how much material you need to shingle a roof. Enter the building length and width and pick the roof pitch (rise over 12), and the tool works out the true sloped roof area, the number of roofing squares, shingle bundles (three per square), underlayment rolls, roofing nails and ridge cap pieces. A waste slider lets you add a margin for cuts and starter courses. Everything runs in your browser — perfect for roofers, contractors and homeowners planning a re-roof.
Features of Our Roofing Calculator
- Roofing squares from footprint and pitch (3/12 to 12/12)
- Shingle bundles at the standard 3 bundles per square
- Underlayment rolls, roofing nails and ridge cap pieces
- Adjustable waste percentage for cuts and starter rows
- Accurate sloped roof area from the pitch multiplier
- 100% client-side and private — instant results, no signup
How to Use the Roofing Calculator
Using this tool is simple and requires no signup or registration. Follow these steps:
- Pick your roof pitch (rise per 12 inches of run).
- Enter the building length and width in feet.
- Set a waste percentage for cuts and starter courses.
- Read off squares, bundles, underlayment, nails and ridge cap.
Frequently Asked Questions About Roofing Calculator
How many bundles of shingles do I need?
You need three bundles of standard asphalt shingles per roofing square (100 sq ft of roof area). First work out the sloped roof area from the pitch, divide by 100 to get squares, then multiply by three and add about 10% waste. This calculator does it all for you.
What is a roofing square?
A roofing square is 100 square feet of roof area — the standard unit for selling roofing materials. Ten squares cover 1,000 sq ft of roof. The pitch matters: a steeper roof has more actual surface area than its flat footprint.
How does roof pitch affect the area?
Pitch is the rise per 12 inches of run. A steeper pitch means more actual roof surface than the flat footprint. A 6/12 pitch multiplies the footprint by about 1.12, while a 12/12 pitch multiplies it by about 1.41. The calculator applies the right multiplier.
How much underlayment and how many nails?
As a planning estimate, one roll of underlayment covers about 4 squares (400 sq ft) and figure about 1.5 lb of roofing nails per square. The calculator gives these totals for your roof.
Is this roofing calculator free?
Yes, completely free with no signup. All estimates run in your browser — nothing is uploaded or tracked.
Why Choose Text Toolbox?
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