Estimate the building envelope

Roofing & exterior calculators

Roofing and exterior calculators translate plan dimensions into surface area and common trade quantities such as roofing squares, shingle bundles, panels, siding squares and linear feet of gutter. Roof slope materially increases surface area, so pitch must be included rather than relying on footprint alone. These tools support budgeting and takeoffs; safe access, structural decisions, flashing and local code compliance require qualified professionals.

12 working calculatorsUS customary unitsReviewed August 3, 2026

Choose the calculation you need

Start with the material or decision in front of you.

Each tool performs a different takeoff or conversion. Open the closest match, enter real measurements, then review the stated assumptions before using the result to buy material.

roofing calculator

Roofing

Estimate sloped roof area and roofing squares from building dimensions, equal overhangs, pitch rise, and a material allowance.

Open calculator roof pitch calculator

Roof Pitch

Convert roof rise and horizontal run into x-in-12 pitch, slope angle, percent grade, and the surface-area multiplier used for takeoffs.

Open calculator shingle calculator

Roof Shingles

Calculate field-shingle bundles, roofing squares, starter bundles, and hip-and-ridge bundles from measured roof and edge quantities.

Open calculator metal roofing calculator

Metal Roofing

Estimate metal roof panels and total panel length from eave width, slope length, roof planes, usable panel coverage, and spare allowance.

Open calculator siding calculator

Siding

Calculate net siding area, siding squares, and cartons from rectangular walls, gables, openings, product coverage, and cutting waste.

Open calculator gutter calculator

Gutters

Estimate gutter footage, stock sections, downspout footage, and downspout sticks from eave runs, allowances, and product lengths.

Open calculator roof cost calculator

Roof Cost

Estimate a roof replacement budget using measured roof area and your local covering, underlayment, removal, labor, and fixed-cost quotes.

Open calculator window replacement cost calculator

Window Replacement Cost

Build a window-replacement budget from opening count, your local installed quote, trim repairs, disposal, permit fees, and contingency.

Open calculator siding cost calculator

Siding Cost

Build a siding budget from measured field area, material waste, and your local material, installation, removal, trim, and contingency prices.

Open calculator gutter cost calculator

Gutter Cost

Build a gutter budget from measured eave length, downspout routes, and your local installed gutter, downspout, removal, accessory, and contingency prices.

Open calculator soffit calculator

Soffit

Estimate soffit area, vented and solid panel units, packages, and channel or trim length from eave dimensions, product coverage, and waste.

Open calculator attic ventilation calculator

Attic Ventilation

Calculate attic net-free ventilation area, intake and exhaust shares, and whole vent counts using your approved ratio and labeled product NFA.

Open calculator

How should you use a project calculator?

Begin with finished dimensions from the actual project area, not a plan that may have changed. Break irregular spaces into simple rectangles, triangles or individual runs and calculate each one separately. Keep units consistent, and measure openings, transitions and obstructions that materially change quantity.

The calculator result is a planning takeoff. Suppliers may sell only whole bags, boxes, panels or stock lengths, so purchase quantities are rounded up. Product-specific coverage, local codes, installation methods and site conditions remain the final authority.

Why does the waste allowance matter?

Waste covers cuts, breakage, unusable offcuts, settlement and measurement variation. A simple rectangular project may need only 5% extra, while diagonal layouts, complex roofs, patterned tile and many corners can require 10–15% or more. The right allowance depends on the material and layout, not a universal rule.

Keep unopened returnable packages separate when a retailer permits returns. For batch-sensitive finishes such as tile, flooring or brick, retaining a small matching surplus can also make future repairs easier.