Free Tool
Free roofing calculator
Enter your footprint and pitch, or your measured roof area, and get squares, shingle bundles, and underlayment rolls with waste built in. Free, no signup.
Private by design — everything you type stays in your browser. Nothing is uploaded, stored, or seen by us.
From footprint to squares
A roof is bigger than the house under it because of the slope. This calculator applies the pitch multiplier so your ground footprint becomes real roof area, then converts to squares.
A square is 100 square feet. Architectural shingles run three bundles to a square, and the tool figures the bundles and the underlayment rolls for you.
Waste is where jobs go over. Ten percent is fine for a simple gable. A cut-up roof with hips, valleys, and dormers eats more, so bump it to 15. Remember that starter strip and ridge cap are separate, so order those on top of the field shingles the tool gives you.
Questions
How many bundles are in a square?
Three, for standard architectural shingles. Some three-tab and heavier shingles differ, so check the wrapper. The calculator uses three.
How do I figure roof area from the footprint?
Multiply the footprint by the pitch multiplier. A 4/12 roof is about 1.05, a 12/12 is about 1.41. Pick your pitch and the tool does it.
How much waste should I add?
Ten percent for a simple roof, 15 percent for one with lots of hips and valleys.
Is this really free?
Yes. No email, no signup, and nothing you type leaves your browser.
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Disclaimer: These free tools and templates are provided for general information and estimating purposes only. All results — including quantities, material and cost estimates, load, sizing, and span figures, scores, and any guidance or warnings — are rough approximations that may not fit your specific project, site conditions, local building codes, or current prices. They are not engineering, architectural, structural, legal, financial, or other professional advice, and are not a substitute for a licensed engineer, architect, contractor, or other qualified professional. Always confirm quantities, sizing, and structural, electrical, mechanical, and code requirements with a licensed professional and your local authority having jurisdiction before purchasing materials or performing any work. Werx makes no warranty as to accuracy and accepts no liability for any decision made using these tools. Use at your own risk. See our Terms of Service.