The quantity of paint required for a project depends on:

  • the area to be painted
  • the condition of the surface to be painted – porous surfaces require more paint
  • whether the surface is flat or profiled – corrugated cladding takes more paint than flat cladding, for example
  • coverage or spreading rate for the selected paint, usually quoted in m2 per litre
  • whether the surface is new material or has been previously painted – new surfaces require more paint
  • the colour of the paint and the colour of the surface it is being applied to. For example, a light-coloured paint over a dark surface may require more coats than a light colour over a light colour.

To estimate the quantity of paint required for a project, calculate the area of the surfaces to be painted for each colour and subtract the areas of openings such as windows and doors. Information about paint coverage for specific paints can generally be found on the paint can. Major paint manufacturers and suppliers have online calculators.

As a rough guide, typical coverage rates are:

  • 10–12 m2/litre for sealer coats
  • 12–16 m2/litre for top coats.