Roofing Sheet Calculator
Estimate how many roofing sheets (mabati) you need for a rectangular roof. Add pitch, overlap, wastage, and optional screw counts.
Measurements
How this is calculated
Roof area = building length × width ÷ cos(pitch angle). This adjusts the footprint for slope on a simple rectangular roof.
Effective sheet area = cover width × sheet length × (1 − overlap ÷ 100)² — overlap reduces usable cover on both dimensions.
Sheets needed = roof area ÷ effective sheet area × (1 + wastage ÷ 100), rounded up.
Typical mabati cover width is about 1 m with 15% overlap — check your supplier's datasheet.
Related reading
Estimates only — roof geometry, valleys, ridges, and off-cuts vary by design. Always confirm with your roofer and order extra sheets.