Room Area Calculator
Get every measurement of a room in one go: floor area, perimeter, wall area and volume, in both metric and imperial. Add an L-shaped extension or bay as an extra rectangle. Use the results for flooring, paint, heating and air conditioning.
Calculate room area
Room formulas
| Measurement | Formula | Used for |
|---|---|---|
| Floor area | length × width | Flooring, carpet, heating |
| Perimeter | 2 × (length + width) | Skirting, coving, gripper |
| Wall area | perimeter × height | Paint, wallpaper, plaster |
| Volume | floor area × height | Ventilation, heating, AC sizing |
L-shaped rooms
Treat an L-shaped room as a main rectangle plus a smaller one sticking out. Enter the main room as length × width, then the extension’s length along the wall it joins and how far it projects. The calculator adds its floor area, and adds two × the projection to the perimeter (the side walls of the extension), which is exact for a rectangular bay or L.
Worked example: 5 × 4 m room, 2.5 m ceiling
- Floor = 5 × 4 = 20 m² (215.3 ft²)
- Perimeter = 2 × 9 = 18 m
- Walls = 18 × 2.5 = 45 m² (before doors and windows)
- Volume = 20 × 2.5 = 50 m³
Area and volume conversions
| From | To | Multiply by |
|---|---|---|
| m² | ft² | 10.7639 |
| ft² | m² | 0.092903 |
| m² | yd² | 1.19599 |
| m³ | ft³ | 35.3147 |
| Acre | m² | 4,046.86 |
Frequently asked questions
How do I calculate the square footage of a room?
Measure the length and width in feet and multiply them. A 12 × 14 ft room is 168 ft².
How do I convert square metres to square feet?
Multiply by 10.764. 20 m² is about 215 ft².
How do I calculate wall area?
Multiply the room perimeter by the ceiling height, then subtract doors (≈ 1.9 m² / 20 ft² each) and windows.
Related calculators
Measure each wall at floor level; older rooms are rarely perfectly square.