Surface Areas
Calculate wall and floor areas
How the calculation works
Pick a shape (rectangle, circle, triangle, trapezoid and others) or rooms with walls and openings, enter the dimensions and get the area in several units. For rooms the net wall area excludes doors and windows.
Formula and assumptions
Rectangle = a × b; circle = π × r²; triangle = ½ × base × height. Room walls = perimeter × height − openings (net, never below 0). Conversions: 1 m² = 10,000 cm² = 1,000,000 mm². Results are rounded only for display.
Worked example
Room 4 × 5 m, height 2.6 m: walls 2 × (4 + 5) × 2.6 = 46.8 m². Door 0.9 × 2.05 = 1.845 m² and window 1.2 × 1.4 = 1.68 m² → net 46.8 − 1.845 − 1.68 = 43.275 m² ≈ 43.28 m².
What affects real consumption
- Measurement accuracy and uneven walls.
- Niches, columns and slopes that need measuring separately.
- Units: check whether the input is in m, cm or feet.
Frequently asked questions
Does the calculator also give ceiling and floor area?
For rooms you can include the ceiling, and the floor has the same area as the ceiling (length × width).
How are doors and windows subtracted?
Enter openings with their dimensions; their area is subtracted from the wall area.