Free wall & ceiling area calculator
Wall & Ceiling Area Calculator
Calculate gross wall area, subtract doors and windows, and total net wall and ceiling square footage across multiple rooms. Use the area breakdown as a starting point for paint quantity, labor planning, and job estimating.
Calculate wall and ceiling square footage
Add each rectangular room separately. For L-shaped or irregular spaces, verify the actual wall surfaces carefully and avoid double-counting shared boundaries when you break the space into measurable sections.
Project area totals
Blank rooms are ignored. Any room you start must be complete and valid before project totals are shown.
Your room measurements are processed in your browser and aren't sent to us.
Area calculation only. This tool does not estimate paint gallons, coats, labor hours, or job price. Measurements for sloped ceilings, stairwells, vaulted walls, or other complex geometry should be broken into measurable sections and verified in the field.
How to calculate wall and ceiling square footage
- Enter the room length, width, and wall height for each rectangular room or section.
- Enter doors, windows, and any other wall areas that will not be painted or covered.
- Review gross wall area, total deductions, net wall area, ceiling area, and room perimeter.
- Add more rooms to build a project-wide area breakdown.
- Copy the summary, export CSV, or print the room-by-room breakdown for estimating or field use.
Wall and ceiling area formulas
2 × (length + width)room perimeter × wall heightgross wall area − doors − windows − other exclusionslength × widthNet wall area is the wall square footage remaining after the opening deductions you enter. Ceiling area is kept separate so you can use wall and ceiling totals independently in later estimating steps.
Wall & ceiling area calculator FAQ
How do I calculate the square footage of all four walls in a room?
For a rectangular room, add the length and width, multiply by 2 to get the perimeter, then multiply the perimeter by wall height. This gives gross wall area before doors, windows, or other exclusions are removed.
Should I subtract doors and windows from wall square footage?
Subtract openings when you want net paintable wall area. This calculator starts each room with editable 21 sq ft per door and 15 sq ft per window values, but you can replace those with measured opening areas when available.
How is ceiling square footage calculated?
For a flat rectangular ceiling, ceiling area is room length × room width. Complex, vaulted, or sloped ceilings should be measured as separate surfaces rather than treated as a flat rectangle.
Can I calculate multiple rooms at once?
Yes. Add each room separately and the calculator totals gross wall area, deductions, net wall area, ceiling area, and room perimeter across the project.
How should I measure an L-shaped room?
This calculator uses rectangular room dimensions. If you break an L-shaped room into measurable sections, account for shared boundaries so they are not counted as real wall surfaces twice, and verify the ceiling area in the field before using the total.
Does this calculator estimate paint gallons?
No. It intentionally stops at square footage. Use the Paint Calculator to apply coat counts, product coverage, ceiling paint, and primer to a specific area or room.