How to Calculate Square Footage: Rooms, Floors, and Irregular Shapes
Whether you're buying flooring, painting a room, or calculating rental costs, knowing your square footage is essential. This guide covers every room shape you'll encounter.
What Is Square Footage?
Square footage (ft²) is the area of a space measured in square feet. One square foot equals a 12-inch × 12-inch square.
In metric countries, the equivalent is square metres (m²). 1 m² = 10.764 ft².
Rectangle or Square Room (Most Common)
Area = Length × Width
Example: A room 15 ft long and 12 ft wide:
15 × 12 = 180 sq ft
Always measure in the same unit — all feet or all metres.
L-Shaped Room
Split into two rectangles, calculate each, then add:
Total Area = Rectangle 1 + Rectangle 2
Example: An L-shaped room with sections 10×12 and 6×8:
(10 × 12) + (6 × 8) = 120 + 48 = 168 sq ft
Triangle
Area = (Base × Height) / 2
Example: A triangular alcove with base 8 ft and height 5 ft:
(8 × 5) / 2 = 20 sq ft
Circle (Round Room or Pool)
Area = π × radius²
Example: A circular room 14 ft across (radius = 7 ft):
3.14159 × 7² = 3.14159 × 49 ≈ 153.9 sq ft
Adding 10% for Waste
For flooring and tiles, always add 10% to account for cuts and waste:
Order = Calculated Area × 1.10
Example: 180 sq ft room → order at least 198 sq ft of flooring.
Converting Between Units
| From | To | Multiply by | |------|----|-------------| | sq ft | sq m | 0.0929 | | sq m | sq ft | 10.764 | | sq ft | sq in | 144 |
Measuring Tips
- Measure at the widest points of each dimension
- Measure multiple times and average the results
- For irregular walls, break into rectangles and add
- Exclude built-in wardrobes only if flooring won't go behind them
Real Estate Square Footage
Real estate agents measure gross internal area — all usable interior space including closets and hallways, but excluding exterior walls, garages, and unfinished basements.
Always ask what's included when comparing property sizes.
Use our Square Footage Calculator to calculate area for any room shape in seconds.