Square footage is the area of a flat surface, measured in square feet. It tells you how much floor, wall or land a space covers. When a home is described as 1,800 square feet, that is the total area of its finished floors. When a box of tiles says it covers 15 square feet, that is the floor area the tiles will cover once they are laid.
What is a square foot?
A square foot is the area of a square that measures one foot (12 inches) on each side. Because each side is 12 inches long, one square foot contains 12 × 12 = 144 square inches.
To find the square footage of a rectangle, you count how many of these one-foot squares fit inside it, which is the same as multiplying its length by its width. A 10 × 12 ft room holds 120 one-foot squares, so it is 120 square feet.
Square feet vs linear feet
Linear feet measure length only, in one direction: the length of a board, a fence or a piece of trim. Square feet measure area, in two directions. A 10-foot board is 10 linear feet long; a 5 × 2 foot rug covers 10 square feet. Lumber, trim and fencing are sold by the linear foot; flooring, tile and sod are sold by the square foot.
How square footage is written
You will see the same unit written in several ways: sq ft, sq. ft., ft², SF and sometimes sqft. They all mean square feet. In construction drawings SF is common; in property listings sq ft is the norm.
Why square footage matters
- Buying and renting: price per square foot is one of the quickest ways to compare homes and commercial spaces.
- Materials: flooring, tile, paint, insulation, roofing and sod are all priced and sold by area.
- Contractor quotes: many trades price their labour per square foot, so an accurate figure helps you compare quotes fairly.
- Heating and cooling: square footage is the starting point for sizing heating and air-conditioning equipment, alongside insulation, climate and windows.
Square footage in other units
| Unit | Equal to | Commonly used for |
|---|---|---|
| 1 square foot | 144 sq in · 0.111 sq yd · 0.0929 m² | Rooms and homes (US, Canada) |
| 1 square yard | 9 sq ft · 0.836 m² | Carpet, turf, landscaping |
| 1 square metre | 10.764 sq ft · 1.196 sq yd | Rooms and homes (UK, Australia, most of the world) |
| 1 acre | 43,560 sq ft · 4,840 sq yd · 0.4047 ha | Land and lots (US, UK) |
| 1 hectare | 107,639 sq ft · 2.471 acres | Land (metric countries) |
Living area, total area and lot size
These three are often confused. Living area is the finished, heated space inside a home. Total area may also include garages, basements and porches. Lot size is the area of the land the home sits on, usually given in square feet or acres. A 2,000 sq ft house can easily sit on a 10,000 sq ft (0.23 acre) lot. Read our guide on calculating the square footage of a house for the details.
Square footage around the world
The US uses square feet for almost everything. Canada is officially metric but still advertises homes in square feet. The UK uses square metres on floor plans and energy certificates, though many estate agents also quote square feet. Australia and most other countries use square metres. Use the square metre calculator when you need both.
Frequently asked questions
What does square footage mean?
Square footage means the area of a surface measured in square feet, the number of one-foot by one-foot squares that would fit inside it.
How do you calculate square footage?
Multiply the length by the width, both in feet. For other shapes, use the matching formula or split the space into rectangles.
What is the difference between square feet and feet?
Feet measure length in one direction. Square feet measure area, length multiplied by width.
How many square inches are in a square foot?
There are 144 square inches in a square foot, because 12 × 12 = 144.
How do I convert square feet to square metres?
Multiply by 0.0929. For example, 1,000 sq ft × 0.0929 = 92.9 m².
Does square footage include walls?
A room’s floor square footage does not include the walls. A home’s official square footage, measured from the outside, does include the thickness of the walls.