If you’re planning on painting the room, you will first have to get all the materials and tools ready, along with the paint. Choosing the paint can often be the hardest step, especially if you need to agree on the exact color with someone else!

**Contents**show

But another thing that some people can struggle with, is calculating the amount of paint needed to paint a room. So we’re going to help you figure it out!

For those that have forgotten their maths, it might seem like a complicated calculation to make. But don’t worry, we’ll guide you through the calculating process, step by step!

- Measure the length of each wall of the room, and add them all together.
- Measure the height of the room, from the floor to the ceiling.
- Multiply the number from step 1 by the number from step 2. The result of this will be the total square footage of the room.
- Next, you have to subtract any surface areas that you aren’t going to paint, such as doors or windows. For this, you need to calculate the square footage of each, by multiplying the length by the height. On average, a door will be around 20 square feet, and a window will be around 15 square feet. So just subtract these values from the overall square footage of the room that you have.
- For the final step, you need to divide the total square footage, by the amount of square footage that a can of paint can cover.

As a general rule, a one-gallon can of paint will cover 350 square feet. So if you’re going to use one-gallon cans, divide your total room square footage by 350.

- The number you end up with is the amount of one-gallon cans of paint that you need! If you end up with an incomplete number, such as three and a half, then we recommend that you round it upwards. After all, it’s better to have some leftover paint, than to run out of paint halfway through the job!

And that’s the basics on how to calculate the amount of paint that you need for a room! With the number telling you how many cans of paint you need to buy.

However, it is important that you take into account the number of layers of paint you’re planning on applying to the walls. The number of paint cans that you got from the previous calculations will be enough to paint the entirety of the room’s surface (minus doors and windows) a single time. If you’re going to add a second layer of paint, you will need to double the amount of paint you buy. And if you want three layers of paint, then triple the result, and so on!

You should also then use the calculations to buy the primer, and the finishing coat, as both of these are very important for a professional paint job. (Although primers and sealers will most often only need a single layer!)

**How do you calculate the square footage for painting?**

When calculating the amount of paint that you need for an entire room, the most important step is figuring out the square footage that is going to be painted. Let’s go over this specific step once more!

- Start by measuring the length of each wall within the room. Add all of these measurements together to get an overall number for the length.
- Measure the height of the room, by measuring from the floor to the ceiling. This is the number for the height.
- Now, multiply the length by the height. The number you get will be the square footage of the room!

However, it does not end there. Once you have the square footage of the room, you need to subtract any surface areas that aren’t going to be painted. After all, if you have doors or windows, they won’t be painted the same as the walls, and therefore you don’t need paint for the entirety of the room’s square footage!

**Here is how to figure out the square footage specifically for painting:**

- Calculate the square footage of each surface area that you are not going to paint. For example doors and windows. To do this, multiply the length by the height like you did with the room.
- Add up all of the square footage of all the areas you are not going to paint. This is now the number for the square footage of no painting.
- Take the square footage of the entire room, and subtract the square footage of the no painting areas.
- The number you get will be the square footage for painting!

**How much paint is needed for a 10×10 room?**

If your room is 10×10, it means that it is 10 feet wide by 10 feet long. The total square footage of this room would therefore be the multiplication of the width times the length, 10 x 10.

The total square footage of this room would be 100 square feet.

So, how much paint is needed for 100 square feet? Well, if you’re aiming to get your paint in one-gallon cans, which is the most common option, then you have to divide by 350. (As 350 square foot is what a gallon of paint can cover)

The result would be 0.2. (Way less than an entire can of paint!)

**How much paint is needed for a 12×12 room?**

If your room is 12×12, it means that it is 12 feet wide by 12 feet long. The total square footage of this room would therefore be the multiplication of the width times the length, 12 x 12.

The total square footage of this room would be 144 square feet.

So, how much paint is needed for 144 square feet? Well, if you’re aiming to get your paint in one-gallon cans, which is the most common option, then you have to divide by 350. (As 350 square feet is what a gallon of paint can cover).

The result would be 0.4. (Almost half of a one-gallon can of paint!)