How To Calculate How Much Paint You Need To Paint A Room

Paint roller painting white wall with blue paint | McAuliffe Painting

Painting a room can not only be a time-consuming project, but if you haven’t calculated how much paint you need, it can be a huge pain when you run out of paint. Not only do you have to spend more money you most likely hadn’t budgeted for, but you also have to drop everything you are doing and run back to the hardware store. Thankfully, McAuliffe Painting are the painting professionals and know exactly how to calculate the required amount of paint needed for any sized room. 

Firstly, determine what type of paint you need

Ensuring that you have the right type of paint for your job is the first step because no matter how accurate your calculations are if are using the wrong type of paint, issues will most likely arise, which means you will have to start all over again. Not only does this hurt your hip pocket because you will need to buy new paint, but it also means you may need to strip back the paint you have already used as it may not allow new paint to bond with the surfaces.

Next, measure the paintable surface area

Knowing the surface area of the area you wish to paint should be your first step in terms of calculations. Luckily, finding the surface area is quite simple. 

First, you need to measure the length of each wall, rounding up to the highest metre-decimal. For example, if the length of the wall measures 12.34 metres, round it up to 12.4 metres. Next, measure the height of the wall, using the rounding up method shown above. Then multiply the two numbers together to get your metres squared (e.g. 12.4m x 2.2m = 27.3 m2). You will be left will excess paint, but over calculating is always better than under calculating, as having extra paint can always be used for touch-ups later down the track.

Now, calculate how much paint to buy

Again, this is another pretty simple calculation. A general rule when it comes to the amount of paint you need is that 1 litre of paint can cover between 6 and 6.5 metres squared of a wall. From there, it is just basic maths. You need to divide the total paintable surface by 6.5. Using the example above, we can calculate the amount needed using the equation below:

27.3m2 surface area / 6.5 = 4.2 litres of paint

Again, using the rule of overestimating, for this surface area, we would buy 5 litres of paint to ensure there is enough paint to cover the entire room, top to bottom.

What else should I consider?

Most of the time, it isn’t as straightforward as measuring and calculating. There are some considerations that need to be made when calculating how much paint to buy.

  1. Is it a repaint or bare drywall? This is important because bare drywall absorbs more paint than if it is a simple repaint. Even if you are using a primer, you will need to buy a little extra to compensate. How much again depends on the surface area.

  2. Is the colour light or dark? If you are using a dark colour, chances are you will need to use a tinted primer, so make sure you factor that into the costs.

  3. You will most likely need to do some retouching. This is why overestimating in terms of how much paint you need can definitely help.

Need a professional opinion? Contact McAuliffe Painting today.

All seem a bit much? Contact the team at McAuliffe Painting today and we can help talk you through the next steps. Our team has over 20 years of experience when it comes to interior painting, and have the skills and knowledge to ensure the job is done right; the first time, every time.

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