What These Calculators Cover
Roofing and exterior material estimation requires converting between different measurement systems. Roofers think in “squares” (100 sq ft), but buy by the bundle. Gutter contractors measure in linear feet but need component counts. Siding can be measured in squares, panels, boards, or board-feet depending on the material type.
These calculators handle the conversions and account for waste, overlap, and accessories like ridge caps, downspout elbows, and starter strips that are easy to overlook when ordering materials.
Roofing & Exterior Guides
Complete Guide to Gutter Sizing
How to choose gutter profiles, size downspouts, and plan drainage for your roof.
How to Estimate Siding Materials
Measuring walls, deducting openings, and choosing between vinyl, fiber cement, and wood siding.
Roof Underlayment & Ridge Cap Planning
Selecting the right underlayment, calculating overlap, and planning ridge cap coverage.
Tips for Roofing & Exterior Projects
- Always measure the actual roof surface area, not the building footprint. Roof pitch increases surface area significantly — a 6:12 pitch adds about 12% more area than the footprint.
- Order 10% extra shingles for waste. Complex roofs with valleys, dormers, and hips can waste 15% or more in cuts.
- Gutter sizing depends on roof area draining to each section, not just building perimeter. A large roof face needs bigger gutters or more downspouts.
- When measuring siding, deduct window and door areas. Vinyl siding has relatively low waste (5-7%), but fiber cement has higher waste due to cutting.
- Ridge cap and underlayment are often forgotten until installation day. Calculate these separately from field shingles.
All Roofing & Exterior Calculators
All calculators in the roofing and exterior category.
Roof Area Calculator
roofing
Calculate true roof surface area from footprint dimensions, accounting for roof pitch, overhangs, and common roof shapes.
Shingles Calculator
roofing
Convert roof area into shingle bundles, squares, and ridge cap quantities for accurate roofing material orders.
Gutter & Downspout Calculator
roofing
Calculate gutter sections, downspouts, elbows, and end caps from roof perimeter, corners, and building height.
Roof Underlayment Calculator
roofing
Calculate rolls of synthetic underlayment or roofing felt needed from roof area with overlap factor applied.
Ridge Cap Calculator
roofing
Calculate ridge cap and hip cap shingle pieces and bundles from ridge and hip lengths.
Siding Calculator
exterior
Calculate siding squares, boards, or board-feet needed from wall area with window and door deductions.