Paint Calculator: How Much Paint Do You Need?

Using our paint calculator will make it easy for you to figure out how much paint you will need for your project. There are only a few components to your personal part in the process, and they are as follows:

  • Perform a height and width measurement on every wall that will be painted.
  • Figuring out whether or not you want to paint the ceiling Deciding how many windows and doors there are in the area
  • Making a decision about the number of coats of paint that will be applied
  • Activate the “calculate” button with your finger.

Let’s take it one step at a time, just in case you think it doesn’t seem simple enough.

Use of the Paint Calculator

The paint calculator is helpful if you are planning on painting either the inside or exterior of your home. It does computations that you are capable of doing yourself if you have a basic understanding of mathematics.

During the computations, the paint calculator will make a few fundamental assumptions, including:

  • It is generally accepted that one gallon of paint will cover roughly 350 square feet.
  • Approximately 20 square feet are accounted for by a typical door.
  • On average, a window takes up about 15 square feet of space.

Tip: If you don’t want to have any problems, you must make sure you’re using the most recent version of your web browser.

Room Configuration and Measurements of the Walls

The first thing you’ll need to do is select the form of the space, followed by inputting the height and breadth of each wall that will be painted. There are four walls that may be painted in rooms that are either rectangular or square in design. Rooms with more intricate shapes may have more than four walls. For instance, a room that is in the shape of an L will have six different wall surfaces that are available for painting.

Pesky windows and doors

You have the option, over on the right-hand side of the calculator, to pick the number of windows and/or doors that are present in the space that you intend to paint. This lets the paint calculator know that the area in question does not contribute to the total square footage being calculated.

Ceiling Paint – Paint Calculator

You may indicate on the calculator that you will also be painting the ceiling of the room you are working on by clicking the checkbox that is located next to the words “Ceiling Paint.” You will then see the total cost of the project. The painting of the ceiling will be treated as a distinct line item in the budget.

The total number of coats

The calculator will always apply two layers of paint as its default setting. Because of this, it is common practise to apply two coats of paint to most walls. This accomplishes two goals: it covers any bare patches left behind by the first coat, and it also provides a barrier or seal that makes the wall easier to clean.

And if you are painting a dark colour over a light colour or a light colour over a dark colour that has been primed over, it is preferable to apply two coats so that any bare or thin patches are covered and smoothed up. However, you may also adjust the number of coats of paint that you want to apply.

Paint Calculator

Consider making a modification to the default value for one of the following reasons:

  • Paints that are of a higher quality and have more pigments and resins might only need one coat.
  • If you want to give a wall a new look while keeping the same colour scheme, you just need to apply one coat of paint.
  • If you want your paint job to last longer, apply two to three coats of paint rather than just one, since this will result in a finish that is substantially more durable.

Modifying your previous entries

  • At any point in time, you are able to make changes to your paint calculation.
  • To make changes to the measures of the square footage, update the fields where the width and/or height should be changed, and then hit “calculate” once again.
  • To add more walls and their dimensions, press the + symbol that is located next to the “add wall” button.
  • To get rid of a wall, select the trash can symbol from the menu.

Starting over:

  • To obtain an updated estimate, choose the configuration of the space you want to use and then input the new dimensions.
  • After that, you should hit “compute” one more time. Keep in mind that if you do this, your current paint calculation will be erased, so you must write down your results.

How the Paint Calculator Operates with Examples

To use the paint calculator, you first need to input the length and height of the walls that are going to be painted, and then you need to enter the number of windows and doors that will be cut into the wall areas. All of the necessary mathematical operations take place behind the scenes to provide a rough but somewhat accurate estimate of how much paint you’ll use. Take, for instance, a space that is 12 feet by 12 feet and has ceilings that are the normal 8 feet in height.

Paint Calculator

The following is the procedure for using the paint calculator:

  • Choose a layout for the room (ours is a basic square).
  • To get the dimensions of each wall, enter its length and height individually (each of our walls is 12 x 8).
  • Make a decision about whether or not you want to paint the ceiling as well (we chose not to).
  • Input the total number of windows and doors that break up the wall space (ours has two windows and one door).
  • Consider whether you want to use one, two, or three coats of paint, and make your decision accordingly (our example uses two coats).
  • Click the button labelled “Calculate.”

The paint calculator will provide you with an estimate of two gallons of paint to use for applying two coats to a room that is twelve feet by twelve feet and has ceilings that are eight feet high. The room has one door and two windows, but you do not plan to paint the ceiling.


You own a shed or garage that has walls on the exterior that measure 25 feet in length and 10 feet in height, giving it a total area of 1,000 square feet. You anticipate that a total of three coats of paint will be required to adequately cover the existing walls. This is due to the fact that the walls have been weathered and are in bad condition. In either your shed or your garage, you will find three windows and one door. If you put all of these numbers into the paint calculator, it will tell you that you will need around 9 gallons of paint to paint your structure.

You could, of course, perform these computations manually if you so desire. But why go through the trouble when you can just use this helpful app and it will do everything for you?

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