Wall Area Calculator
Work out the exact paintable wall area of a room — doors and windows deducted, ceiling optional — in square feet, square metres and square yards.
Every painting job starts with one number: how many square feet of wall are there? This calculator is that number — no paint, no coverage, just the area, with openings deducted and the ceiling optional.
Measure once here, then carry the result into the paint, primer or wallpaper calculator.
Your results
Enter your measurements and press Calculate.
Quantities are rounded up to whole tiles, planks, boxes or bags, after the wastage allowance. Cost appears only when you enter a price.
Formula
All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.
How to use this calculator
- Measure the room length, width and height.
- Count the doors and windows.
- Choose whether to include the ceiling.
- Use the total in the paint, primer or wallpaper calculator.
Worked example
| Room | 12 ft × 15 ft × 8 ft high |
|---|---|
| Gross wall area | 2 × (12 + 15) × 8 = 432 ft² |
| Deductions | 1 door (21 ft²) + 2 windows (2 × 15 ft²) = 51 ft² |
| Paintable walls | 432 − 51 = 381 ft² |
| Ceiling | 12 × 15 = 180 ft² |
| Total | 381 + 180 = 561 ft² = 62.33 yd² |
Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.
Frequently asked questions
Why do I need a wall area calculator?
Because paint, primer and wallpaper are all sold by area — and the area is not the floor area. This page gives you the one number every other calculator on this site needs, so you measure once and use it everywhere.
What size is a standard door or window for the deduction?
This calculator uses a door of 3 × 7 ft (21 ft² / 1.95 m²) and a window of 3 × 5 ft (15 ft² / 1.39 m²). If your openings are much larger — patio doors, picture windows — measure them and subtract the extra separately.
Should the ceiling be included?
Only if you are painting or wallpapering it too. For wall paint, leave it out; for a whole-room estimate, include it and use the total.
How do I measure a room that is not a rectangle?
Split it into rectangles, calculate each one here, and add the totals. L-shaped rooms are two rectangles; a bay window is a small extra rectangle.
Related calculators
Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.