Roofing & siding calculators

Roof Pitch Calculator

Enter rise and run, or span and height, and get the pitch in every form, its multiplier and what roofing it can take.

Roofing Calculator

Enter the house footprint, overhangs and pitch, or measured roof planes, and get the roof area in squares and a full shingle material list.

Rafter Calculator

Enter span, pitch and overhang to get the rafter length, the cut angles, the birdsmouth and the board to buy, drawn to scale.

Shingle Calculator

Enter the roof in squares or square feet, pick the shingle, and get bundles, starter, hip and ridge cap and nails.

Metal Roof Calculator

Enter the house or each roof plane and the panel type to get panel count and lengths, screws, trim, closures and underlayment.

Roof Truss Calculator

Enter span, pitch, overhang and building length to get the truss count, top chord length, heights and a drawing of the webs.

Gutter Slope Calculator

Enter the gutter run and slope to get the total drop, a mark for every hanger and the downspouts for your roof and rainfall.

Roof Square Calculator

Roof squares = roof area in sq ft / 100; a 1,503 sq ft roof is 15.03 squares, or 50 bundles of architectural shingles with 10% waste.

Roof Sheathing Calculator

Roof sheathing sheets = roof sq ft x waste / 32; a 1,503 sq ft roof with 10% waste needs 52 sheets of 4 x 8 ft plywood or OSB.

Roof Snow Load Calculator

Flat roof snow load = 0.7 x Ce x Ct x Is x ground load; a 40 psf ground load on a heated house is 28 psf, or 37 lb per foot on a rafter 16 in on center.

Siding Calculator

Measure the walls and gable ends, pick a siding, and get squares, pieces, trim and nails to order.

Vinyl Siding Calculator

Enter the walls, gables, windows and eaves, and get vinyl siding cartons, every accessory and the soffit to order.

Hip Roof Calculator

Hip rafter length = (half the width + overhang) x √(2 + slope²); a 40 x 30 ft house at 6/12 needs 24 ft hip rafters and 1,503 sq ft of shingles.

Gambrel Roof Calculator

Gambrel roof area = length x 2 x (lower slope + upper slope); a 36 x 24 ft barn with 18/12 and 6/12 pitches has 1,469 sq ft of roof and a 12 ft ridge height.

Soffit Calculator

Soffit area = eave length x depth; 80 ft of eave 12 in deep is 80 sq ft, or 8 vinyl panels of 12 in x 12 ft with 10% waste.

Attic Ventilation Calculator

Attic vent area = floor area / 150 (or / 300); a 1,500 sq ft attic needs 1,440 sq in, half at the soffits and half at the ridge: 40 ft of ridge vent.

Gutter Size Calculator

Roof area per downspout = gutter capacity / rainfall intensity; at 6.78 in/h a 5 in K-style gutter serves 814 sq ft between downspouts.