40 ft of walls, 9 ft height, 60 sq ft openings
- Net area = 300 sq ft
construction calculator
Wall Area Calculator
Calculate square footage of wall surfaces after subtracting door and window openings.
Results
- Net wall area (sq ft)
- 300.00
How to use this calculator
- Enter total wall length and height.
- Add up door/window openings and enter their combined area.
- We subtract openings from the gross area to show net wall square footage.
Inputs explained
- Wall length
- Combined length of all walls you’re covering, in feet.
- Height
- Wall height in feet. Use ceiling height for full walls.
- Openings
- Total square footage of windows, doors, or built-ins to subtract.
How it works
We multiply wall length by height to get gross area, then subtract the total area of windows, doors, or built-ins.
Formula
Area = (length × height) − openings
When to use it
- Estimating paint, primer, or wallpaper coverage.
- Sizing drywall or paneling for a series of walls.
- Comparing coverage needs before and after adding or removing openings.
Tips & cautions
- Measure openings carefully—large picture windows can greatly reduce paintable area.
- If wall heights differ, run separate calculations per height and sum results.
- Add a waste factor separately for finishes that require overlap or multiple coats.
- Assumes consistent wall height across the measured length.
- Does not include trim, ceiling, or baseboard areas.
- No waste factor built in—add your own for paint, wallpaper, or drywall seams.
Worked examples
30 ft, 8 ft tall, 40 sq ft openings
- Net area = 200 sq ft
Deep dive
Calculate net wall area by entering total length, height, and openings to size paint, drywall, or wallpaper needs.
Great for DIYers and contractors who want a quick square footage check before buying materials.
FAQs
- Do I need to split walls?
- Enter the combined length of contiguous walls. For different heights, run the calculator per wall.
- How do I handle trim?
- Add trim coverage separately. This tool focuses on wall surfaces only.
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Measurements rely on user inputs. Confirm onsite before purchasing materials.