Roofing Sheet Calculator — Estimate Sheets Needed

For a sloped roof, measure the actual slope length (not just the horizontal/plan area). Roof Area = Plan Area ÷ cos(roof angle). A roof with a 30° slope and 50m² plan area has an actual area of 50 ÷ cos(30°) = 57.7m². This calculator accepts either plan area with a slope angle, or direct measured roof area.

Side overlap is typically one corrugation (varies by profile, commonly 150-200mm effective coverage loss per joint). End overlap (where sheets meet lengthwise on long roofs) is usually 150-200mm. This reduces the effective usable area of each sheet — always calculate using effective coverage width, not the sheet's total width.

Standard widths are around 1.05-1.09m (effective/covering width after overlap, from a total sheet width of ~1.25m). Lengths are typically custom-cut to order, commonly ranging from 6 to 12 feet (1.8m to 3.6m), though longer custom lengths are available from manufacturers.