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How To Measure A Room To Determine The Quantity Of Paint To Buy

For handy men, who have had difficulty in calculating the precise amount of paint that would be sufficient for a room, this post is for you. Knowing how to blend colours and being familiar with the easy steps to painting is not enough. That alone wouldn’t  get you an excellent score in painting.

It’s important you understand how to accurately measure the amount of paint you need to buy for your space. So, enjoy these clear and easy steps to measuring your room space. It will help you determine the exact quantity of paint you need.

Due to the variety of sizes of gallons available, let’s go through how to measure your wall. Afterwards, you can check the label of the chosen paints to know how many of a particular size you’ld need.

For Walls 1

You might need to refresh your math skills if you have thrown it to the winds. Simply use a calculator if the calculations prove too difficult for you. This measurement is for one coating.

  • Measure out the length of the four sides of a room wall from side to side and add up the sizes to get the feet sum. For example, if the sides are 1.11 meters each: 1.11 +1.11+1.11+1.11 = 1.52 meters.
  • Measure out the height of the wall and multiply it by the total length of the wall. For example, if the height of the wall is 9, the total wall area will be 48 x 9 = 40 square meters.
  • An average door is about 1.8 square meter, while an average window is 1.3 square feet. Consider that there are two windows and a door in the room. Subtract the sum of the windows and the door from the area of the wall. That is if you want to use a separate paint colour for the window and door than what you use for the wall. For example: 1.8+1.3+1.3 = 4.4, subtracted from the area of the wall: 40-4.4= 35.4 square meter.

For Walls 2

  • To use the same colour of paint for your wall, you will need paint that would cover 35.4 square meter. You may also want to use a different colour for the walls and another for the door and windows. For that, buy paint enough for 35.4 square meter for the wall and 4.6 square meter for the door and windows.
  • Supposing the label on your choice of paint shows that the paint would cover 5.6 square feet in two coatings and you need to cover 39.2 square meters, simply divide 39.2 by 5.6. This would give you about 7.2 gallons. That means that 7 and half gallons would be enough. As this would be enough for two coatings, you won’t need to double the result to achieve two coatings as was earlier stated.

For Ceilings

  • Measure out the length of the ceiling and multiply the figure by the width, to get the area of the ceiling. For example, if the room has equal sides like the example used above, both the width and length would be the same: 1.11 x 1.11=1.23 square meter. Do the division for the amount of paint as you did for the walls.

Note that the figures used in this post are just samples and could differ from what you calculate. Happy Measuring!

Send in your comments if you need clarification on this post. You can also visit any Sandtex Experience Center for help.

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  1. Tai Arowojolu-Alagwe


    I think there is an error in the calculation above due to the division of a quantity in square meter (m2) by another quantity in square feet (f2). There is a need for conversion of all quantities to same unit. E.g. convert the quantity in square feet to square meter before dividing.
    This is my humble opinion.

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