Square Footage Calculator
Square footage is the standard floor area unit for real estate listings in the US, while most of the rest of the world uses square meters. Knowing how to measure accurately and convert between the two systems is essential whether you're buying, renting, or comparing properties across borders. This guide covers the formulas, common room sizes, and international context.
Formulas
- Area (sq ft) = Length (ft) × Width (ft)
- Area (m²) = Area (sq ft) × 0.0929
- Area (sq ft) = Area (m²) × 10.764
- Quick mental check: sq ft ÷ 10 ≈ m² (within ~8%)
How to Measure Square Footage
For a rectangular room, measure the length and width in feet and multiply them together. A 12-foot by 15-foot bedroom is 180 sq ft. For irregular rooms (L-shaped, with alcoves, or with angled walls), break the floor plan into rectangles, calculate each separately, and sum the results.
In real estate, interior square footage is standard — measuring from interior wall to interior wall, not including wall thickness. Finished basements and garages may or may not be included in listed square footage; always confirm with the listing agent what is and isn't counted.
International listings use m² almost universally outside the US. Canadian listings often show both ft² and m². UK listings use m² for new builds and often ft² for older homes. Australian listings use m².
Common Room & Home Sizes
| Space | Dimensions | Square Feet | Square Meters (m²) |
|---|---|---|---|
| Small bedroom | 10 × 10 ft | 100 sq ft | 9.3 m² |
| Standard bedroom | 12 × 12 ft | 144 sq ft | 13.4 m² |
| Large bedroom | 14 × 14 ft | 196 sq ft | 18.2 m² |
| Living room | 15 × 20 ft | 300 sq ft | 27.9 m² |
| Large living room | 20 × 20 ft | 400 sq ft | 37.2 m² |
| 1-bedroom apartment | — | 650 sq ft | 60.4 m² |
| 2-bedroom apartment | — | 950 sq ft | 88.3 m² |
| Small house | — | 1,000 sq ft | 92.9 m² |
| Average US home | — | 2,300 sq ft | 213.7 m² |
US average home size based on US Census Bureau data. Apartment and house figures are approximate national averages.
Frequently Asked Questions
How do I calculate the square footage of an irregular room?
Divide the room into rectangles, measure each section's length and width, calculate length × width for each section, then add all the results together. An L-shaped room is typically split into two rectangles — measure each arm of the L separately. For triangular sections, use area = 0.5 × base × height.
How do I convert square feet to square meters?
Multiply sq ft by 0.0929 to get m². For example, 1,500 sq ft × 0.0929 = 139.4 m². To go the other way (m² to sq ft), multiply by 10.764. A quick mental shortcut: divide sq ft by 10 to get a rough m² figure — it's about 8% high but close enough for quick estimates.
What is the average home size in the US vs UK?
The average US single-family home is around 2,300 sq ft (213.7 m²). The average UK home is roughly 818 sq ft (76 m²) — about one-third the size. Australia's average is approximately 2,032 sq ft (189 m²). These differences reflect land availability, construction norms, and cultural preferences rather than income levels alone.