Wall Area Calculator – Square Feet for Paint & Tile

A wall area calculator finds the surface area of a flat, rectangular wall. It multiplies the wall's height by its width and gives the result in square feet. Builders, decorators, and homeowners use it to work out how much paint, tile, wallpaper, or drywall a wall needs.

Wall Area Formula

For a rectangular wall, area equals height times width:

$\text{Area} = \text{Height} \times \text{Width}$

Height is the vertical distance from floor to ceiling. Width is the horizontal distance from one corner to the other. Both measurements must use the same unit, usually feet. The result is in square feet (sq ft).

A wall that curves, slopes, or has an irregular shape is not a single rectangle. To find its area, split it into rectangles and triangles, calculate each part, then add the results together.

How to Calculate Wall Area

1. Measure the height of the wall from floor to ceiling.
2. Measure the width of the wall from one corner to the other.
3. Enter both numbers in feet. If a measurement was taken in inches, divide it by 12 first.
4. Multiply height by width to get the area in square feet.

The calculator opens with a sample wall of 8 feet by 10 feet. It only accepts positive numbers. If a box is empty, or holds zero, a negative number, or text, the calculator shows "Enter values to see results" instead of an area. Results are rounded to two decimal places. Below the result it draws a labeled rectangle of the wall, which is not to scale.

Worked example

A wall 8 feet high and 10 feet wide has an area of:

8 ft × 10 ft = 80 square feet

For a wall with decimal measurements, such as 8.5 feet high and 12.25 feet wide:

8.5 ft × 12.25 ft = 104.125 square feet, which the calculator rounds to 104.13 square feet.

Units and Conversions

This calculator works in feet and square feet, the standard units in the United States. One foot is defined as exactly 0.3048 meters, so the area conversions are exact too:

• 1 square foot = 0.09290304 square meters exactly, or about 0.0929
• 1 square meter = about 10.7639 square feet
• 1 square yard = 9 square feet, because a yard is 3 feet

Materials made outside the United States often list coverage in square meters, so a conversion may be needed before comparing them to a result given in square feet.

Estimating Materials from Wall Area

Wall area is the starting point for estimating how much of a material to buy. The exact amount needed also depends on the material and on the size of any openings, such as doors and windows.

Paint: A gallon of interior paint typically covers 250 to 400 square feet, depending on the paint and the surface. Interior doors are usually 80 inches tall, so a 30-inch-wide door covers about 16.7 square feet and a 36-inch-wide door covers exactly 20 square feet. A 3-foot by 5-foot window covers 15 square feet. Subtracting these openings from the wall area gives a closer estimate of how much paint is needed.

Tile: Tile installers commonly add 10 to 15 percent to the calculated area to allow for cuts, breakage, and future repairs.

Wallpaper: A standard American single roll holds about 35 square feet of paper, but trimming and matching the pattern at the seams usually leave only 25 to 30 usable square feet.

Drywall: Standard drywall sheets measure 4 feet by 8 feet, an area of 32 square feet each. Installers usually calculate the full wall area, since sheets are cut to fit around outlets, doors, and windows during installation.

Frequently asked questions

Should I subtract doors and windows from the wall area?

For paint and wallpaper, subtracting the area of doors and windows gives a more accurate estimate of how much material is needed. For drywall and similar sheet materials, the full wall area is normally used, since sheets are cut to fit around openings after they are installed.

What if the wall is not a rectangle?

Split it into rectangular and triangular sections, calculate the area of each one, and add them together. The area of a triangle is half its base times its height.

How do I convert square feet to square meters?

Multiply the number of square feet by 0.09290304. For example, 100 square feet is 9.290304 square meters, or about 9.29.

Can this formula be used for floors and ceilings?

Yes. A floor or ceiling area is also length times width, as long as the shape is rectangular.

How accurate do my measurements need to be?

For paint, measuring to the nearest inch is accurate enough, since paint is sold in fixed sizes such as quarts and gallons. For materials like tile or wallpaper, where cost and waste matter more, measuring to the nearest quarter inch gives a better estimate.

Why does the calculator show a rounded result?

The calculator rounds the area to two decimal places for readability. A wall measuring 8.5 by 12.25 feet has an exact area of 104.125 square feet, which the calculator displays as 104.13.