Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Add up multiple roof plane areas into a total roof area, for roofs with several separate sloped sections.
1500 sqft
Many real roofs aren't one simple pitched rectangle -- they're several separate sloped sections (planes) meeting at ridges, hips, and valleys, each with its own area. This calculator sums as many plane areas as your roof has into one accurate total, rather than trying to force a single footprint-and-pitch calculation to fit a complex roof shape.
Enter each roof plane's area separately (measured directly, or calculated per-section using the Roofing Calculator's slope-factor method for each section). Add or remove plane entries as needed to match your roof's actual number of sections.
Total Roof Area = Plane 1 + Plane 2 + Plane 3 + ...
A single footprint-times-pitch calculation assumes one uniform roof shape and pitch across the whole building. Real roofs with dormers, wings, or mixed pitches need each distinct section measured and summed on its own for an accurate total.
Use this for a complex roof with multiple wings, dormers, or mixed pitches. Once you have a total area, the Roof Shingle Calculator converts it directly into shingle bundles.
Start by sketching the roof from above and label every distinct sloped face. Gable ends have two main planes, hip roofs have four, and additions, dormers, and porches add more. Rectangular planes are easy: length along the slope times width. Triangular planes, such as hip faces, use half of the base times the slant height. Trapezoid planes, which are also common on hip roofs, use the average of the two parallel edges times the slant height.
Imagine a hypothetical hip roof with two trapezoid planes and two triangle planes. Each trapezoid has parallel edges of 40 and 20 feet and a slant height of 15 feet, so its area is (40 + 20) / 2 x 15 = 450 square feet. Each triangle has a base of 30 feet and a slant height of 15 feet, so its area is 0.5 x 30 x 15 = 225 square feet. The total is 2 x 450 + 2 x 225 = 1,350 square feet, or 13.5 squares.
Rectangle = Length × Slant Width
Triangle = ½ × Base × Slant Height
Trapezoid = (Edge 1 + Edge 2) ÷ 2 × Slant Height
A common mistake is measuring horizontally across the house and treating that as the plane width. The roof surface runs along the slope, so its length is longer than the horizontal distance. If you only have horizontal measurements, multiply by the slope factor from the Roofing Calculator to convert them to the real sloped dimension. Measuring on the slope itself avoids this, but is riskier physically, so prefer drawings or measurements from the attic where possible.
Skylights, chimneys, and large vents remove roof surface. For estimating shingles, many roofers subtract only large openings, because the material saved around a small opening is often offset by the extra cuts it needs. If you enter a plane's area directly, subtract any large openings from that plane before adding it.
If your roof is simple, run the Roofing Calculator on the footprint and compare the totals. They should be close. A big difference suggests a measuring mistake in one of the planes, or an overhang that was included in one method and not the other.
Each plane can be measured directly (length x width of that sloped section) or calculated from its own footprint and pitch using the slope-factor method in the Roofing Calculator.
For a precise material order, yes -- subtract any significant openings from the relevant plane's area before entering it, though small penetrations are often absorbed by the standard waste allowance.
You can add as many as your roof has. Use the add and remove controls to match the number of sections.
Yes, measure each plane out to the eave and rake edge, since shingles cover those areas.
Yes, so use the same unit for each plane you enter. Divide by 100 to convert to roofing squares.
Yes. Each sloped face of a dormer roof is its own plane, and its walls are not part of the roof area.