How to Calculate Square Footage

Square footage is the lingua franca of real estate and DIY. It's the number on a property listing, the figure behind a paint estimate, and the unit you'll hear every time someone quotes a price per square foot for a room or a whole house. The good news is that the core calculation could hardly be simpler: it's a single multiplication.

Square footage measures floor area — the two-dimensional size of a floor's surface. For a rectangular or square room, that's just length times width. Once you've got that number you can plan flooring, estimate paint, size up a rental, or compare property listings fairly.

The formula

Square footage = length × width

Both dimensions must be in feet (or converted to feet first). The result is in square feet (ft²).

Worked example

A rectangular room 10 ft × 12 ft:

10 × 12 = 120 square feet

That 120 ft² is your floor area. If you're planning materials, this figure becomes the starting point for almost everything else.

Metre conversion

Outside the US (and in many Indian listings that use metres or square yards), you'll often measure in metres. Convert each dimension, or the final area:

1 m = 3.28084 ft
1 m² = 10.7639 ft²

A 4 m × 3 m room:

4 × 3 = 12 m²
12 × 10.7639 ≈ 129 square feet

It helps to remember the 10.76 figure — dividing square feet by it converts back to square metres.

Planning materials

The biggest practical pay-off of knowing your square footage is buying the right amount of material:

• Flooring — add roughly 10% for cutting waste and mistakes. A 120 ft² room needs about 132 ft² of tiles or planks.
• Paint — roughly 350 sq ft per gallon per coat (about 100–120 sq ft per litre). Two coats means doubling the coverage.
• Rent and property — Indian listings may quote sq ft, sq m or square yards (1 sq yd = 9 ft²), so a quick conversion keeps you comparing apples to apples.

Common unit notes

Here are the conversions most frequently needed:

Unit	Equals
1 acre	43,560 ft²
1 cent	435.6 ft²
1 marla	~272.25 ft²
1 sq yd	9 ft²

The acre and the cent (a subunit common in South Asian land deals) both knock cleanly into square feet, which makes quoting and comparing easy.

Irregular and L-shaped rooms

Not every room is a neat rectangle. If you have an L-shaped or other odd space, split it into rectangles, calculate each separately, and add the results:

Part A: 10 × 8  = 80 ft²
Part B:  6 × 5  = 30 ft²
Total            = 110 ft²

For more complex shapes, break them into triangles and rectangles, compute each, and sum. Any odd floor plan becomes approachable once you slice it into simple shapes.

Key takeaways

• Area = length × width, both in feet.
• Convert metres by multiplying ft² by 10.7639 (or divide to go the other way).
• Add ~10% waste for flooring and double for paint coats.
• Split irregular rooms into rectangles and add the pieces.

FAQ

Is square footage just floor area? Yes — it measures the floor surface. Buildings also use "rentable" and "usable" figures that include or exclude shared areas, which is a different (and more complicated) concept.

How do I convert square metres to square feet? Multiply by 10.7639 (or about 10.76). Going the other way, divide by 10.76.

Should I include walls in the measure? For interior floor area, typically not — you measure wall-to-wall floor space. Wall area matters separately for paint and wallpaper.

What's a square foot vs a square yard? A square yard equals 9 square feet (3 ft × 3 ft). Many Indian listings use sq yd, so remember the ×9 relationship.

Measure your space with the Square Footage Calculator, and if you need a box's volume instead, head to the Cubic Feet Calculator.