The Wall Calculator calculates the net area of a wall — length × height minus doors and windows — and turns it into a quick materials list: 4 × 8 drywall sheets, paint for two coats, studs and plate length.
Enter the wall size, the number and size of doors and windows, and your stud spacing. For block, brick, stone and retaining walls, framing details, tile, panels or cost estimates, use the dedicated wall calculators listed below the tool.
Wall Calculator
Wall area and a quick materials list — drywall sheets, paint, studs and plates — for any wall with doors and windows.
Formula
- Net wall area: A = L × H − (doors × door area) − (windows × window area)
- Drywall sheets (one side): A ÷ 32 ft² × 1.10, rounded up
- Paint (two coats, one side): A × 2 ÷ 350 ft² per gallon
- Studs: L ÷ spacing + 1, rounded up
- Plates (1 bottom + 2 top): 3 × L
Where L = wall length and H = wall height.
How the Calculation Works
Step 1: Multiply wall length by height to get the gross area.
Step 2: Subtract each door and window (width × height × quantity) to get the net area.
Step 3: Convert the net area into materials using the assumptions shown in each result, and count studs from the wall length and spacing.
Variables Explained
| Input | Meaning | Unit |
|---|---|---|
| Wall length, height | Size of the wall | ft, in, m |
| Doors, windows | Quantity and size of openings | in, ft, m |
| Stud spacing | Distance between stud centers | in, mm |
Example Calculation
Given: wall 20 ft × 8 ft, one 36 × 80 in door, one 36 × 48 in window, studs at 16 in
Gross area: 20 × 8 = 160 ft²
Openings: door 20 ft² + window 12 ft² = 32 ft²
Net area: 128 ft²
Drywall: 128 ÷ 32 × 1.1 = 4.4 → 5 sheets
Paint: 128 × 2 ÷ 350 ≈ 0.73 gal
Studs: 20 ft ÷ 1.333 ft + 1 = 16 studs; plates: 60 ft
Common Area Conversion Table
| Unit | Equivalent |
|---|---|
| 1 m² | 10.7639 ft² |
| 1 yd² | 9 ft² |
| 4 × 8 ft sheet | 32 ft² ≈ 2.97 m² |
Material Estimation Notes
Built-in assumptions
This quick estimate uses 4 × 8 ft sheets with 10% extra for cuts, and 350 ft² per gallon of paint. Paint coverage varies by product and surface, so check the label and use the Paint Calculator for a detailed estimate.
Extra studs
The stud count is for straight field studs only. Corners, door and window openings (king and jack studs), and blocking need more — the Wall Stud and Wall Framing calculators include those.
Waste Factor Considerations
Walls with many openings, angles or short pieces create more offcuts. Increase the drywall quantity if your wall has lots of cuts, and remember that area is not the same as the amount to buy — sheets and cans come in fixed sizes.
Frequently Asked Questions
How do you calculate the square footage of a wall?
Multiply length by height, then subtract doors and windows.
How many sheets of drywall do I need for a wall?
Divide the net wall area by the sheet area (32 ft² for 4 × 8) and add extra for waste.
How many studs do I need for a 20 ft wall?
At 16 in on center: 20 × 12 ÷ 16 + 1 = 16 field studs, plus extras for corners and openings.
Should I subtract windows and doors from wall area?
For paint and drywall, yes. Some painters subtract only large openings; the calculator subtracts every opening you enter.
How much paint do I need for one wall?
Net area × number of coats ÷ the paint’s coverage per gallon.