General Calculation Tips
As a rule of thumb, always plan to have enough for two coats of paint. Take the square footage of your ceiling into your personal calculation if you’d like to include it in your paint project. As applicable, you should make sure that windows, entry doors, and non-paintable areas such bathtubs, surrounds, cabinets, and tiled areas are not included (because who wants to paint their tub?). Painting projects for entire rooms are based on a wall coverage factor of 350 square feet per gallon of paint. If you’re unsure of exactly how much paint you need, we included some average estimates below. Aim to buy an extra gallon of paint in the event that you need extra, and also for future touch-ups.
How to Calculate Square Footage for Painting
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 should be calculated individually. After all wall areas are determined, these figures are added together. Since doors and windows do not receive paint, you should exclude them by subtracting their combined areas. Ceiling square footage is calculated by multiplying the width of one wall by the width of an adjacent wall. No exclusions are made for ceiling elements such as light fixtures or smoke alarms.
Bathroom Painting
How Much Paint to Use for a Powder Room
Floor Size: 20 square feetWall Space: 124 square feetUse: 1 gallon of paint
Because they have no bathtub or shower, powder rooms walls are usually in such good condition that two coats with one gallon of paint is sufficient. This sample calculation excludes 20 square feet for one entry door from the total wall space. Powder rooms tend not to have windows.
How Much Paint to Use for a Small Bathroom
Floor Size: 40 square feetWall Space: 108 square feetUse: 1 gallon of paint
For a small bathroom with minimal wall problems, you can usually purchase just one gallon of paint. This calculation excludes one entry door, one window, and 65 square feet of wall space for a bathtub and surround.
How Much Paint to Use for a Medium Bathroom
Floor Size: 120 square feetWall Space: 252 square feetUse: 2 gallons of paint
For this bathroom calculation, excluded are both a window and an entry door, along with 65 square feet for the tub/surround.
How Much Paint to Use for a Large Bathroom
Floor Size: 160 square feetWall Space: 316 square feetUse: 2 gallons of paint
For this large bathroom, two gallons of paint will comfortably cover all wall areas with a little paint to spare. This calculation excludes both a window and an entry door from the total wall space. An alcove tub and surround calculated at 65 square feet of wall space are excluded, as well.
Kitchen Painting
Kitchens are heavy-use areas, so they always require a thorough paint job. At the same time, kitchens tend to have limited wall space due to the base and wall cabinets, reducing the amount of paint you will need. Buy quality paint in eggshell or semi-gloss sheens for easier kitchen cleanup.
How Much Paint to Use for a Small Kitchen
Floor Size: 100 square feetWall Space: 243 square feetUse: 2 gallons of paint
Plan on purchasing 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 wall space square footage.
How Much Paint to Use for a Medium Kitchen
Floor Size: 200 square feetWall Space: 383 square feetUse: 2 gallons of paint
Use two gallons of paint for two coats of paint in average-sized kitchens. One door, one window, and 62 square feet of base and wall cabinet space are excluded to produce the total wall space.
How Much Paint to Use for a Large Kitchen
Floor Size: 300 square feetWall Space: 515 square feetUse: 3 gallons of paint
The sample net calculation of paint for a large kitchen excludes two windows and one door from the total wall space, along with 75 square feet of base and wall cabinet space.
Bedroom Painting
Bedrooms use a lot of paint. Though walls are usually in good condition and rarely require more than two coats of paint, there usually is a lot of wall space since most bedrooms have few built-in obstructions.
How Much Paint to Use for a Small Bedroom
Floor Size: 150 square feetWall Space: 345 square feetUse: 2 gallons of paint
The sample net calculation excludes both a window and two doors from the total wall space. One door is the entry door. The other door is a single-width closet door occupying 20 square feet of unpainted wall space.
How Much Paint to Use for a Medium Bedroom
Floor Size: 200 square feetWall Space: 405 square feetUse: 3 gallons of paint
Medium-sized bedrooms will use about three gallons of paint. With this calculation, one window and three doors are excluded. One of those doors is an entry door. The other two doors account for a double-width closet door that uses 40 square feet of unpainted wall space.
How Much Paint to Use for a Large Bedroom
Floor Size: 300 square feetWall Space: 565 square feetUse: 4 gallons of paint
With this large primary bedroom calculation, excluded are one entry door, one window, and two additional doors to account for a double-width closet occupying 40 square feet of unpainted wall space. Read more about our Diversity and Inclusion Pledge to make The Spruce a site where all feel welcome.
