Paintable Area and Coverage Formula
Paintable area is calculated per room as wall area (2 x (Length + Width) x Height, plus ceiling area if selected), minus standard deductions for doors (2 sq.m each) and windows (1.4 sq.m each). Paint volume is then found by multiplying the net area by the number of coats and dividing by the coverage rate, which defaults to 12 sq.m per liter for emulsion paint.