Enter your Room Shape, Wall Length, Wall Width, and Ceiling Height, then add the number of doors and windows with their dimensions to calculate your Total Wall Area — giving you the Gross Wall Area minus the space taken up by openings, so you know exactly how much surface you're actually working with.
Total Wall Area
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Gross Wall Area
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Total Door Area
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Total Window Area
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To calculate wall square footage, multiply the total wall length by the ceiling height to get gross area, then subtract the area of doors and windows. The formula is: Wall Area = (Wall Length × Height) - (Door Area + Window Area).
A 12-foot wide by 12-foot high wall has 144 square feet of area (12 × 12 = 144). However, you'll need to subtract any doors or windows to get the paintable area.
A 10-foot by 10-foot wall contains 100 square feet of surface area. Remember to account for doors, windows, or other openings that won't need paint or wallpaper.
For painting or wallpapering, subtract door and window areas from your total wall area since you won't be covering these surfaces. This gives you the actual area that needs material.
For a rectangular room, measure the length and width, then calculate the perimeter: (Length + Width) × 2. Multiply this by ceiling height for total wall area, then subtract openings.
Standard interior doors are typically 7 feet tall by 3 feet wide (21 sq ft). Standard windows vary but average around 3 feet by 4 feet (12 sq ft). Measure your specific openings for accuracy.
It's recommended to buy 10-15% extra paint beyond your calculated wall area to account for waste, touch-ups, and future repairs. This ensures you have enough material and color matching.
Yes, this calculator works for both interior and exterior walls. For exterior walls, be sure to account for all windows, doors, and any architectural features that won't be painted or covered.