Square Footage Calculator

How the square footage calculator works

Square footage is the area of a space in square feet:

Area (ft²) = length (ft) × width (ft)

Measure wall-to-wall at floor level. If your tape reads in feet and inches, convert the inches to decimal feet (inches ÷ 12). For example, 12 ft 6 in = 12.5 ft.

Worked example: a 12 ft × 15 ft bedroom

1. 12 × 15 = 180 ft²
2. In metric: 180 × 0.0929 = 16.7 m²

Irregular rooms

• L-shaped rooms: split into two rectangles, calculate each, and add them.
• Closets and bays: measure separately and add.
• Triangles: base × height ÷ 2.
• Circles: π × radius².

For a whole house, add up every room. For listings, square footage is usually measured to the outside of external walls, which is larger than the sum of the rooms. Check which method a figure uses before you compare.

Converting

Australian floor plans often use "squares": 1 square = 100 ft² ≈ 9.29 m².

Common mistakes

• Mixing feet and inches, such as entering 12.6 for 12 ft 6 in (it should be 12.5).
• Measuring above skirting or cabinets instead of at floor level.
• Counting areas twice where rooms overlap in an L-shape.

How do I calculate the square footage of a room?

Multiply the length by the width in feet. A 10 ft × 12 ft room is 120 ft².

How many square feet in a square metre?

About 10.764 square feet.

How big is a "square" in Australian house plans?

One square is 100 ft², about 9.29 m². A 25-square house is about 232 m².

Written by Sam Alex, civil engineer. About the author