Home Improvement

Painting

Estimate Paint Amounts Based on Square Footage

By

Emily Manchester

Emily Manchester

Emily Manchester is the General Manager of Better Homes & Gardens. She has been working in the home space for six years, and in digital content for eight years. Previously, Emily led all editorial and strategy decisions for The Spruce and MyDomaine, two other home brands under the Dotdash Meredith umbrella.

Learn more about The Spruce'sEditorial Process

Updated on 08/05/24

This paint coverage calculator makes calculating the amount of paint you'll need for your project nearly automatic. Your role in the process involves just a few elements:

- Measure the height and width of each wall to be painted.
- Add in the number of windows and doors in the space.
- Decide if you want to paint the ceiling.
- Decide how many coats of paint you'll apply.
- Press the "Calculate" button.

When calculating how much paint you will need, you will also need to consider other variables such as how many coats, the brand of paint, and how thick the coats are.

## How Much Paint Do I Need?

The paint calculator helps plan an interior or exterior home painting project. It automates calculations you could make yourself using fairly basic math skills. The calculator makes several basic assumptions in its computations, each based on a specific formula that many people use when calculating paint needs. For example, one gallon of paint is assumed to cover approximately 350 square feet, a standard door accounts for about 20 square feet, and an average window accounts for about 15 square feet.

### Room Shape and Wall Dimensions

Choose the room shape, then count the number of walls in your room. Add up the total length of the walls, then multiply by wall height to get the total square feet. Then, subtract the measurements of the windows and doors. Rectangular and square rooms have four walls to be painted. L-shaped rooms have six wall surfaces, while others may have more.

### Windows and Doors

To paint windows and doors, first, count the number of windows and doors in the room. Then, subtract the area of the windows and doors from the total wall area you need to paint.

### Ceiling Paint

If you are painting the ceiling, calculate the square footage by multiplying the ceiling's length by its width. Then, divide this number by the coverage rate in the paint label, which usually takes into account two coats of paint.

### Number of Coats

Select how many coats you plan to use to paint the room. The calculator automatically defaults to two coats. It's typical to paint most walls twice to ensure against bare or thin spots and to create a seal or barrier that makes the wall easier to clean. You might want to change the default if:

- Using high-quality paint with more pigments and resins; these specialty paints may only require one coat.
- Refreshing a wall with the same paint color; one coat is great for a touch-up coat.
- Plan ahead by using three coats, the paint job will last longer than two coats.

### Tip

If you're using a paint sprayer, you may need to adjust your calculations. Sprayers may use up to 30 percent more paint than rollers.

## How to Use a Paint Calculator

Paint calculators estimate the amount of paint you will need based on the size and shape of your room. Imagine you have a 12-foot by 12-foot room with standard 8-foot-high ceilings. Here's how to use the calculator:

- Pick a room shape; in this case, a square.
- Enter the length and height of each wall; in this example, each wall is 12 feet by 8 feet.
- Decide if you want to paint the ceiling; in this example, do not checkmark it.
- Enter the number of windows and doors in the room; in this example, select two windows and one door.
- Decide if you want to apply one, two, or three coats of paint; keep the default of two coats.
- Hit the "Calculate" button.

Automatically, the paint calculator gives you an estimate of 2 gallons of paint for applying two coats to a 12 x 12 room with an 8-foot ceiling with two windows, and one door. The painting of the ceiling is not included.

### Tip

You can copy the provided embed code if you'd like to add this paint calculator to your website or blog. Once you've finalized your measurements and other specifications, click or tap "Embed This Tool" to generate a code that you can insert into your website

FAQ

How much paint do I need for a 12x12 room?

For a 12x12 room with average 8-foot ceilings, you will need approximately 1.5 gallons of paint.

How much paint is needed to paint the interior of a 2,000-square-foot house?

You will need about 5 gallons of paint to paint the interior of a 2,000-square-foot house. One gallon of paint covers about 360 to 400 square feet, so if you divide 400 by 2,000, you will get 5 gallons of paint.