How to Calculate How Much Paint You Need

If you're embarking on a painting project, the last thing you want is to spend too much or too little on the paint you need.

If you buy too little, you will interrupt your project to run back to the store, if you buy too much and you will be left with cans that you cannot safely dispose of. Before you roll up your sleeves, make sure you know how to calculate the amount of paint needed.

An easy-to-use paint calculator will help you determine how much paint is needed for the home improvement activity, while staying within a comfortable range.

Additionally, we help you calculate paint amounts for some basic room types. These are rough estimates; precise ink needs vary depending on your project.

General calculation tips

As a general rule of thumb, always plan to have enough for two coats of paint. Consider the square footage of your ceiling in your personal calculation if you want to include it in your painting project.

As applicable, you need to make sure that windows, entry doors, and non-paintable areas like bathtubs, fences, cabinets, and tiled areas are not included (why who wants to paint the tub?).

Whole room painting projects are based on a wall coverage factor of 350 square feet per gallon of paint. If you are unsure of how much ink you need, here are some average estimates.

How to calculate square footage to paint

The square footage, or area, of a wall is determined by multiplying the width of the wall by the height of the wall. The area of each wall must be calculated individually.

Once all the areas of the wall have been determined, these figures are added together. Since the doors and windows do not receive paint, you must exclude them by subtracting their combined areas.

The square footage of the ceiling is calculated by multiplying the width of one wall by the width of an adjacent wall. There are no exclusions for ceiling elements such as light fixtures or smoke detectors.

Bathroom paint

How much paint to use for a powder room
Floor Size: 20 sq. Ft.
Wall space: 124 square feet
Usage: 1 gallon of paint

As they do not have a bathtub or shower, the walls of the bathrooms are usually in such good condition that two coats with a gallon of paint are enough. This sample calculation excludes 20 square feet for one entry from the total wall space. Bathrooms tend to have no windows.

How much paint to use in a small bathroom
Floor Size: 40 sq. Ft.
Wall space: 108 square feet
Usage: 1 gallon of paint

For a small bathroom with minimal wall problems, you can usually only buy a gallon of paint. This calculation excludes a doorway, a window, and 65 square feet of wall space for a tub and trim.

How much paint to use in an average bathroom
Floor Size: 120 sq. Ft.
Wall space: 252 square feet
Usage: 2 gallons of paint

For this bathroom calculation, we exclude a window and a doorway, along with 65 square feet for the tub / frame.

How much paint to use for a large bathroom
Floor Size: 160 sq. Ft.
Wall space: 316 square feet
Usage: 2 gallons of paint

For this large bathroom, two gallons of paint will comfortably coat all areas of the wall with a little paint to spare. This calculation excludes one window and one doorway from the total wall space. A built-in bathtub and a trim calculated at 65 square feet of wall space are also excluded.

Kitchen paint

Kitchens are heavily used areas, so they always require meticulous painting. At the same time, kitchens tend to have limited wall space due to base and wall cabinets, reducing the amount of paint needed. Buy quality semi-gloss paint or eggshell to make kitchen cleaning easier.

How much paint to use in a small kitchen
Floor size: 100 square feet
Wall space: 243 square feet
Usage: 2 gallons of paint

Plan to buy two gallons of paint for all types of small kitchens. One door, one window, and 42 square feet of base and wall cabinets are excluded from the square feet of wall space.

How much paint to use in an average kitchen
Floor size: 200 square feet
Wall space: 383 square feet
Usage: 2 gallons of paint
Use two gallons of paint for two coats of paint in medium kitchens. One door, one window, and 62 square feet of base and wall cabinet space are excluded to produce total wall space.

How much paint to use for a large kitchen?
Floor Size: 300 sq. Ft.
Wall space: 515 square feet
Usage: 3 gallons of paint

The net paint sample calculation for a large kitchen excludes two windows and one door from the total wall space, along with 75 square feet of space.

Bedroom painting

The rooms use a lot of paint. Although the walls are generally in good condition and rarely require more than two coats of paint, there is generally a lot of room on the walls as most rooms have few built-in obstructions.

How much paint to use in a small room
Floor Size: 150 sq. Ft.
Wall space: 345 square feet
Usage: 2 gallons of paint

The net sample calculation excludes one window and two doors from the total wall space. A door is the front door. The other door is a single-width closet door that takes up 20 square feet of unpainted wall space.

How much paint to use in an average room
Floor size: 200 square feet
Wall space: 405 square feet
Usage: 3 gallons of paint

Medium-sized rooms use about three gallons of paint. With this calculation, one window and three doors are excluded. One of these ports is a gateway. The other two doors represent a double-width closet door that uses 40 square feet of unpainted wall space.

How much paint to use in a large room
Floor Size: 300 sq. Ft.
Wall space: 565 square feet
Usage: 4 gallons of paint

With this large master bedroom calculation, an additional entry door, window, and two doors are excluded to account for a double-width closet occupying 40 square feet of unpainted wall space.