Wall Square Feet Calculator
Net Wall Area
Total Price
Wall Diagram
InteractiveHow to Calculate the Square Feet of a Wall
Wall square footage is the vertical surface area you need to cover with paint, wallpaper, tile, or cladding. Unlike floor area, which is horizontal, wall area is measured by multiplying the wall's length by its height. Openings such as doors and windows are subtracted to give you the net paintable or coverable area.
Basic Wall Area Formula
Measure the full length of the wall from corner to corner, and the full height from floor to ceiling. Multiply them to get the gross wall area. If you're painting four walls, calculate each wall separately or calculate one and multiply by the number of identical walls.
Wall Area Formula
FormulaExample: 15 ft wall × 9 ft ceiling − 21 sq ft door = 114 sq ft
Subtracting Doors and Windows
A standard interior door is approximately 3 × 7 ft = 21 sq ft. A standard window is roughly 3 × 4 ft = 12 sq ft. Use the "+ Add Opening" feature in the calculator to subtract any number of doors, windows, or architectural niches from the gross wall area automatically.
Which Direction to Measure?
Always measure the wall's interior surface — not the exterior. In most residential construction, interior walls are measured from corner to corner at baseboard level. The height is measured from the finished floor surface to the ceiling (not to the top plate).
What Wall Square Footage Is Used For
Paint Quantity Estimation
Interior paint covers roughly 350–400 sq ft per gallon. Divide your net wall area by 350 (conservative) to find the number of gallons needed for one coat. For two coats, double the result. Textured or porous surfaces absorb more — reduce coverage to 300 sq ft per gallon.
Wallpaper and Tile Coverage
Wallpaper rolls typically cover 25–30 sq ft. Divide your net wall area by the roll coverage to determine how many rolls to purchase. For wall tile, add 10–15% waste to your net area and divide by the tile's stated coverage per box.
Drywall and Cladding
Drywall sheets are standardized at 4 × 8 ft (32 sq ft) or 4 × 12 ft (48 sq ft). Add 10% waste to your net wall area and divide by sheet size to calculate the number of sheets needed for a new room or remodel.
Insulation Estimation
Batt insulation is rated by wall cavity size and sold in packages covering a stated square footage. Calculating net wall area (excluding openings) gives you the correct total insulation required for an energy-efficient installation.
Specialized Square Feet Calculators
Each tool is purpose-built with its own dedicated calculator, visual diagrams, and step-by-step guidance.
Triangle
Find the area of any triangle using base × height or Heron's formula with three side lengths.
Irregular Shape
Break any complex shape into rectangles and triangles. Add sections and sum them automatically.
Inches
Enter measurements in inches and get instant square feet results. Includes a quick-reference conversion table.
From Meters
Convert metric measurements to square feet. Perfect for international real estate and imported materials.
Linear Feet
Convert linear footage to square feet for lumber, carpet, fencing, decking, and rolled materials.
Sq Meters
Convert sq ft to sq m with live dual display. Essential for international real estate and architecture.
Sq Yards
Divide sq ft by 9 to get sq yd. Perfect for carpet ordering, sod purchases, and fabric estimates.
Acres
Convert property area from sq ft to acres. Ideal for land sales, farming, zoning, and lot size comparisons.
Cubic Feet
Add depth to any area to calculate volume. Essential for concrete, mulch, soil, gravel, and pool planning.
House
Add rooms one by one and get your home's total square footage, with a live bar chart breakdown per room.
Room
Measure rectangular or L-shaped rooms for flooring, paint, and renovation budgeting with instant cost estimates.
Wall
Get net wall area for paint, wallpaper, or tile by subtracting doors and windows from the gross surface.
Tile
Enter room size and tile dimensions to calculate tile count, boxes to buy, and total material cost including waste.
Concrete
Get slab area, cubic yards of concrete, bags needed, and pour cost for any project.
Land
Measure any property lot or parcel in sq ft and acres. Supports rectangular, triangular, and irregular shapes.
Cost
Estimate total project cost from area and price per square foot. Compare scenarios with tax and markup.
Flooring
Find exact flooring material for hardwood, laminate, vinyl, or carpet with waste factor and box count.
Roof
Get true roof surface area using pitch multiplier. Includes roofing squares, shingle bundles, and cost.
Paint Area
Get paintable wall area with door and window deductions. Calculates gallons, coats, and total paint cost.
Estimation
Add multiple areas, apply buffer percentages, and get quick estimates for budgeting any project.
Frequently Asked Questions
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.