Calculate Roof Squares,
Factor Pitch Multipliers.
Free roofing calculators: true roof area from footprint and pitch, shingle squares and bundles, underlayment rolls, and replacement cost.
True Slope Geometry
A 4:12 pitch adds 5.4% surface area; a steep 12:12 pitch adds 41.4% to flat footprints.
3 Bundles per Square
Standard architectural asphalt shingles package 3 bundles per 100 square feet.
Starter Strip & Ridge Caps
Add perimeter eaves starter shingles and ridge cap bundles plus valley ice-and-water shield.
RoofMath Calculators
Roof Area Calculator (by pitch)
True roof surface from the house footprint and pitch — the slope multiplier that footprints hide.
Shingle Bundle Calculator
Bundles and squares of shingles for your roof — with starter strip, ridge cap, and the 10% waste.
Roof Replacement Cost Calculator
Replacement cost by squares and shingle tier — tear-off, materials, labor, and the add-ons quotes hide.
Roof Pitch Multiplier Table
The slope factor for any pitch — plus rise, rafter length, and what each pitch means for walkability and materials.
Building Code & Methodology
How to read a roofing quote like the roofer wrote it
The line items that matter, the substitutions that cost you in year five, and the three-quote discipline.
Ventilation: the shingle-life variable nobody prices
Why attics that breathe keep shingles alive, and the intake/exhaust balance that does it.
12 mistakes people make with roofing projects
The recurring errors we see in roofing projects — what causes each one, and the habit that prevents it.