How much paint do I need?
First you need to gather the following information.

1. Surface area of the surface(s) to be painted.
2. Spreading rate of the paint being used.
3. The number of coats needed.

Example:

1. To paint the living room walls - not including the ceiling. The walls are 3m high, with a total of 18m of wall length (allowing for doors and windows) the surface area is 3m x 18m = 54m².
2. The walls are currently painted and are in good condition. Resene Zylone Sheen - low sheen acrylic is selected and has a theoretical spreading rate of 11 square metres per litre.
3. Because the walls are previously painted and in good condition, only two coats of Zylone Sheen will be required.

To work out how much paint is needed:

• Take the surface area and put into Box 1 below
• Take the spreading rate and put into Box 2
• Take the number of coats needed and put into Box 3
  
  i.e. (Box 1 / Box 2) x Box 3 = the required litres of paint needed
  e.g. (54m² / 11m²/L) x 2 coats = 9.8 litres in total (ie a 10 litre pail)
  
  Warning: If your web browser is not able to run JavaScript then you will not see a Calculator below!!

m2 / m2/L * coats Calculated result: Litres in total NB: Porous surfaces and shapes (ie corrugated iron) will require more paint.

Quick steps to estimate paint litres from house plans
To get a rough idea of how much paint you will approximately need when you only have house plans to work from, use the following calculations…

Look for the statement of area on the house plans – e.g. 186m²

Divide this by
10 = litres of sealer for ceilings
5 = litres of 2 coats for ceilings
4 = litres of sealer for walls
2 = litres of 2 coats for walls
25 = litres of primer for trim/doors/frames
15 = litres of 2 coats for trim/doors/frames

Enter the square area (m²) of house plan below and press "Calculate"

Disclaimer.
This quick estimate works as a general guide for most houses, but extreme designs or colour palettes tailored to each room will need a more careful approach with each room calculated individually.