Paint Calculator

THIS PAINT CALCULATOR WILL TELL YOU HOW MUCH PAINT YOU WILL NEED

This paint calculator will give you a square foot total to take to your local paint store
How Much Paint Do I Need Formula: Wall area - 20 square feet per door - 15 square feet per window. All of this multiplied by the number of coats and divided by 350 square feet per gallon.

How Much Paint Do I Need Definition: One of the least expensive ways to update your home is by painting it. It is probably the most cost effective method as well, but you really need to know how much paint you actually need. If you buy too much paint, you will have wasted some money. If you do not buy enough paint, you will have to return to the store to get more. Take a quick moment to calculate your paint needs now!

The basic formula for deciding how much paint you need is simple for the wall area. You need to figure out the dimensions of your room. Multiply the length and the width of your room. Once you have that information, subtract 20 square feet for each door in the room and 15 square feet per window. A gallon of paint typically covers about 350 square feet. Take the wall area and divide it by 350 to find the amount of paint that you will need to paint one coat. No need to do these calculations on a piece of paper of a standard calculator. Simply enter the below inputs into the calculator for a quick easy calculation!

How to Use the Calculator: The first inputs of the above paint calculator, you will be asked for the height and length of your walls. You put in that information along with the number of doors and windows that are in the room. Remember that this calculator is based upon the standard measurements. Oddly shaped windows may skew the results, so take that into consideration. You will then have to put in the number of coats that you expect to paint. In most cases, two coats of paint are usually plenty.

1. Height of the Walls: The height of the walls is measured in feet. The calculator also assumes that you have perfectly rectangular or square rooms. If you have slanted ceilings, you may need less paint than the calculator figures. To get this measurement, use a tape measure to measure the distance from the ceiling to the floor. Most walls are 8 or 10 feet high.

2. Length of the Walls: The length of the walls will vary, and they are also measured in feet. If you have a rectangular room, you will only need to measure the one side and double it. A square room will only require you to measure one wall and multiply that number by four. The length of walls is not typically a standard measurement. You will likely get the best measurement if you have someone else help you to hold the measuring tape.

3. The Number of Doors: For this part of the calculation, you will need to simply type in the number of doors that you have. French doors will count as two doors. Be sure to include any closet doors in the calculation as well.

4. The Number of Windows: Simply count all of the windows in the room that you are going to paint. Remember that the calculator is based upon a standard fifteen square foot window. Add that number to the calculator.

5. Number of Coats of Paint: The typical number of coats is two. If you are going over a darker color with a lighter color, you may require some additional coats. Putting a darker color over a lighter color may only require one coat. It is best to plan on two coats, but add or subtract at least one coat if you are drastically changing the color scheme.

Calculate: Once all of the information is in the online calculator, click on the calculate button. Your results will be given to you and you can head to the store to get your paint.
Painting Formula: = (Room Length x Ceiling x 2) + (Room Width x Ceiling Height x 2) + (Room Length x Room Width)

Painting Definition: A fresh coat of paint is the cheapest and easiest way to give your home a new look. For your next painting endeavor, try our free painting calculator to ensure the project flows smoothly. This online calculator will help you greatly!


Find How Much Paint is NeededSimply enter the height, width, and length of the area or room you wish to paint and presto, you’re given the total square footage of the space you need to cover.

When you go to purchase the paint at a home improvement or hardware store, inform the clerk of the number of square footage that you plan to paint, along with the brand and color, and they should be able to prepare the correct number of gallons you’ll need.

Depending on your project, you may need to adjust the amount of square footage to accommodate for specific conditions. Here are some handy tips to keep in mind when deciding what sort of coverage the job requires.

  • If you’re beginning with a light colored, smooth base that’s either primed or already painted one coat coverage may suffice when applying light colored paint. In this instance, you can use the exact number of square footage quoted by this calculator, and one gallon of paint should cover about a 350 square foot space. However, if you’re applying a dark color you may need two coats to achieve accurate color expectations. Therefore, you’ll have to double the quoted square footage which will knock the square foot coverage per gallon down to 175.
  • If you’re beginning with a dark colored, smooth surface and using a lighter paint, you will need to apply one or two coats of primer before applying the paint if you’re looking to achieve a one-coat finish. Without primer, solid coverage will require about three coats; either way you’ll have to triple the amount of square footage when purchasing.
  • If you’re painting a textured surface, double the square footage for light paint and triple it for dark, as it will take more paint to seep into the cracks and crevices.
  • If you’re working with raw materials such as drywall, wood, or metal it’s imperative that you prime before painting to achieve a uniform color. A single coat may do, but for professional results two is preferred. Just as with painting over dark colors, if un-primed, raw materials will generally take about three coats of paint to achieve a conventional finish.
  • For trim, measure the length, width, and height of each piece. Add the figures together by category and enter the results into the calculator. Then follow the instructions above according to material or surface condition.
Basically stated, for each coat of paint or primer needed for an area, you’ll need to buy enough paint to cover the amount of square footage quoted by the calculator. For those who are not accustomed to square foot calculations, the painting calculator can be a very handy tool in planning home renovations. Utilizing this program and following the tips above will make your next painting project a breeze.

How to Calculate Painting: Let's be honest - sometimes the best painting calculator is the one that is easy to use and doesn't require us to even know what the painting formula is in the first place! But if you want to know the exact formula for calculating painting then please check out the "Formula" box above.