Calculating the amount of paint needed depends largely on the surface area of the wall in the room.
Here are the steps to take when you want to do your painting:
STEP 1: Measure out the perimeter of the room i.e the entire length of the four sides of the room or as the case may be.
STEP 2: Measure out the height of the room i.e from the floor to the ceiling, these could be in meters or in feet depending on the unit of measurement you want to use.
STEP 3: Now calculate the surface area of the room which is simply by multiplying the total length of the room by the height (i.e your measurement from floor to the celling) of the room.
For example, a standard Nigerian room is usually 3.6m x 3.6m or 12ft x 12ft others can be 3.6m x 3.0m or 12ft x 10ft depending on the plan of the house.
STEP 4: After you have calculated the surface area of the walls, you are going to measure out the openings in the room, i.e the windows and doors.
For Windows, the height of windows is mostly 1.2m i.e 4ft, while the width usually varies. So the size may be 1.2m x 1.2m i.e 4ft x 4ft or 1.5m x 1.2m i.e 5ft x 4ft, or 1.8m x 1.2m i.e 6ft x 4ft,e.t.c. To get the area of each window opening, multiply the height of the window by the width.
For Door openings, the height is usually 2.1m i.e 7ft, while the width usually varies. The size of doors may be 0.7m x 2.1m or 2ft 4’’ x 7ft or 0.9m x 2.1m i.e 3ft x 7ft or 1.5m x 2.1m i.e 5ft x 2.1ft e.t.c. To get the area of each door opening, multiply the height by the width.
STEP 5: Sum the total areas of window and door openings in the room then subtract from the total surface area of the walls, the result will be the area of the wall that will be painted.
After determining the area of your wall in ft2 or m2, then choose your paint.
SO HOW DO WE APPLY THIS TO THE PAINT?
Check the label of the paint bucket for the spread rate for the paint. Spread rate is the number in ft2 or m2 of surface each coat of paint will cover. After you find that, divide the total surface area of the wall you calculated earlier by this number to determine the number of paint buckets/litre you will need for each room.
Note that the number of coats you should apply depends on the colour, type of paint, method of application and the nature of the surface.
For example, you will likely need a second coat of paint when covering a dark color with a lighter one.
Do have a nice day.