How Much Paint Do I Need -PaintRight Colac Paint Calculation Guide

September 21, 2017

To determine how much paint you need for your job you will need the following information

  1. Room Measurements
  2. Square Metre Area of the surfaces to be painted (Walls excluding windows and doors etc)
  3. Square Metre Spreading rate of the paint being used
  4. The number of coats required


You will need to measure up the room


Surface Areas in Square Metres

Ceiling Area: (Length x Width) 3m x 4m = 12 Square Metres

Tip: Remember Ceiling Area is also the Floor Area if you require floor coverings


Window Area: (Length x Width) 2.1m x 2.6m = 5.4 Square Metres

Door Area (1 Side): (Length x Width) 2.1 x .9 = 1.8 Square Metres

Build In Robe (1 Side): (Length x Width) 2.1m x 2.5m = 5.2 Square Metres


Walls: (Add Wall Lengths Together) 4m + 3m + 4m + 3m = 14m Room Perimeter

 (Multiply Room Perimeter by Ceiling Height) 14m x 2.7m = 37.8m Square Metres

(Add Window, Door, Build In Robe Square Meters Together) 5.4m + 1.8m + 5.2m = 12.4m Square Metres

(Wall Square Metres) 37.8m – 12.4m (Take Window, Door, Build In Robe Square Metres) = 25.4m Square Metres (Round Figure Up)

Wall Area To Be Painted = 26 Square Metres


Spread Rate of Paint Recommended

The spread rate/ coverage rate of paint depends on how porous the surface area is – for example raw timber and plasterboard absorb more paint then already coated timber and plasterboard surfaces. You will need to take this into considerations, when looking at recommended paint spread rates / coverage rates. Check with your Local Paint Specialists for what type of paint is best for your surface area.

Most Haymes interior paint spread rate is around 12 Square Metres Per 1 Litre


Number of Coats of Paint Recommended

Number of coats of a paint product refers to the film build of the paint to ensure it stands up on the surface to wear and washability. Always double check with us at PaintRight Colac if you’re not sure.

Primer Sealers and Undercoats are usually 1 Coat

Top Coats Colours for walls and ceilings are usually 2 Coats

Clear Coatings for timber floors and bench tops are usually 3 Coats


          Formula To Calculate How Much Paint You Need