Enter room dimensions and the number of doors and windows. The calculator works out floor, wall and ceiling areas and quantities of paint, flooring, tiles and skirting, including an allowance for cuts and breakage.
By default we use 1.9 m² per door, 1.6 m² per window, paint coverage of 10 m² per litre, two coats and a 10 % allowance. You can adjust all of this to the product you chose.
That depends on height and the number of openings. Enter the rooms in the calculator and you get the quantity for walls and ceiling. Then check the coverage on the can.
For straight laying usually 10 %, for diagonal or complex patterns up to 15 %. The spare also covers future repairs.