Wall Square Foot Calculator

Multiply the wall's length by its height. For example, a wall that is 15 feet long and 9 feet tall equals 135 square feet. Subtract any doors or windows to get the net wall area.

Most interior paints cover 350–400 square feet per gallon. For rough or porous surfaces, plan for 300 sq ft. Always buy slightly extra to account for touch-ups and second coats without color batch differences.

Yes for precision budgeting. A standard door opening (21 sq ft) and window (12 sq ft) can add up to nearly a full gallon of paint savings on a large room. Use our deduction feature to subtract them automatically.

Calculate the perimeter (2 × Length + 2 × Width), then multiply by the ceiling height. For a 12×10 room with 9 ft ceilings: (2×12 + 2×10) × 9 = 44 × 9 = 396 sq ft of gross wall area before subtracting openings.

A standard interior door is 32–36 inches wide and 80 inches tall. That equals approximately 17.8–20 square feet. A common industry shorthand is 21 sq ft to account for the frame opening.

12 feet × 9 feet = 108 square feet. This is common for a living room accent wall. After subtracting one standard door (21 sq ft), the net area would be 87 square feet.

Calculate the net wall area (after subtracting windows and doors). Divide by the wallpaper roll's coverage (typically 25–30 sq ft per single roll, or 56 sq ft per double roll). Always add one extra roll for pattern matching and waste.

Yes — both use Length × Width. For floors, Width is the room's width. For walls, "Width" is the ceiling height. The formula is identical; only the dimensions being measured differ.

A 10×10 wall is 100 square feet. That's a common bedroom or office wall size. One gallon of paint (350 sq ft coverage) will easily cover it with two coats.

Professional painters measure each wall's length and height, multiply for gross area, then subtract doors (≈21 sq ft each) and windows (≈12 sq ft each). They add 10% for waste and calculate paint gallons by dividing total area by 350.

For interior painting and finishing, always measure the inside face of the wall — from corner to corner at baseboard level. Exterior measurements are only used for siding, exterior paint, or structural calculations.

Not in wall area calculations. Ceilings are calculated separately (Length × Width of the room). If painting an entire room, add wall area + ceiling area for total paintable surface.

Trim (baseboards, crown molding, door casings) is typically excluded from wall area calculations since it's painted separately with a different type of paint. Subtract trim area only if you need extreme precision.

Divide your total wall area by 175 (half of 350 sq ft per gallon). For example, 400 sq ft of wall needs about 2.3 gallons for two coats. Always round up and buy an extra quart for touch-ups.

Primer covers approximately 300–400 sq ft per gallon, similar to paint. For new drywall or dark-to-light color changes, plan for one full coat of primer. Divide your net wall area by 350 for the number of gallons.

Standard drywall is 4×8 ft (32 sq ft) or 4×12 ft (48 sq ft). Divide your total wall area by the sheet size, then add 10–15% for waste and cuts. For a 400 sq ft room, you'd need about 14 sheets of 4×8 drywall.

12 × 9 = 108 square feet. This is one of the most common wall sizes in residential homes, typically found in living rooms and master bedrooms.

An "8 foot wall" refers to ceiling height. The square footage depends on the wall's length: an 8 ft high × 10 ft long wall = 80 sq ft; an 8 ft × 12 ft wall = 96 sq ft; an 8 ft × 15 ft wall = 120 sq ft.

At 350 sq ft per gallon, 500 sq ft requires about 1.43 gallons for one coat. Buy 2 gallons for one coat (with leftover for touch-ups), or 3 gallons for two full coats.

Yes. A standard window is about 12 sq ft (3×4 ft). On a large wall with multiple windows, this can save you half a gallon or more of paint. Our calculator's deduction feature handles this automatically.

If you're painting inside the closet, yes — measure closet walls separately and add them to your total. If you're only painting the main room walls, exclude closet interiors but include the wall surface around the closet door opening.

To measure the square feet of a wall, multiply the wall's length by its height (Length × Height). For example, a 15-foot long wall that is 9 feet tall equals 135 square feet.

To measure the square footage of a wall, measure the length and height in feet, and multiply those two numbers together (Length × Height = Square Footage).

To find the square footage of a wall, multiply the wall's width (length) by its height. Subtract any doors or windows to find the net square footage.

To find the area of a wall, multiply the wall's length by its height. For example, a wall that is 12 feet long and 8 feet high has an area of 96 square feet.

Calculate wall area by multiplying the wall's length by its height (Length × Height). Subtract any door or window openings to get the net paintable area.

To calculate the area of a wall in square feet, measure its length and height in feet and multiply them together.

Multiply the wall's length in inches by its height in inches to get square inches, then divide by 144 to convert to square feet. For example, (180 inches × 108 inches) ÷ 144 = 135 sq ft.

You cannot calculate wall area directly from floor area alone. You need to calculate the room's perimeter (2 × Length + 2 × Width) and multiply it by the ceiling height.

Find the room's perimeter by adding the lengths of all walls together, then multiply that perimeter by the ceiling height. Subtract doors and windows for the net square footage.

Measure the perimeter of the building's exterior and multiply it by the height of the walls. Subtract any exterior doors, windows, or garage openings to find the net area.

Determine a wall's square footage by multiplying its horizontal length by its vertical height. Subtract the area of any doors or windows to find the net wall surface area.

To find wall area, multiply the wall's length by its height. For example, a 10 ft by 8 ft wall has a total wall area of 80 square feet.

Measure the wall's length from corner to corner and its height from floor to ceiling. Multiply the two measurements together to get the total wall square footage.

Find a wall's square footage by multiplying its width by its height. Subtract the dimensions of windows and doors for an accurate net square footage estimate.

Calculate boundary wall area by multiplying the total length of the boundary wall by its height. For example, a 100 ft long boundary wall that is 6 ft high equals 600 square feet.