Square Feet
Square Meters
Square Yards
Square Inches
Table of Contents
What is square footage?
Square footage is a measurement of area in two dimensions, expressed in square feet (sq ft or ft²). It tells you how much surface a region covers — whether that is a floor, a wall, a piece of land, or a tabletop. Knowing the square footage of a space is essential for everything from buying flooring and paint to comparing home sizes and calculating real estate prices.
How to calculate square footage
The method depends on the shape of the area you are measuring. For most rooms in a house, the floor is rectangular, and the formula is simply length × width. Measure both dimensions in feet (convert inches by dividing by 12) and multiply them together.
If your space is not a simple rectangle, break it into smaller shapes you can measure separately. A typical living-and-dining room with an L-shape can be split into two rectangles; calculate the area of each and add them together for the total.
Square footage formulas by shape
Rectangle or square: length × width
Triangle: ½ × base × height
Circle: π × radius²
Trapezoid: ½ × (top + bottom) × height
This calculator handles all four. Just pick your shape from the dropdown, enter the measurements in feet, and your area is instantly converted to square feet, square meters, square yards, and square inches.
Converting between units
If you measured in inches instead of feet, convert before multiplying. There are 12 inches in a foot, so 18 inches = 1.5 feet. Alternatively, multiply your inch measurements together and divide by 144 — that converts square inches to square feet in a single step (since 12 × 12 = 144).
To convert square feet to square meters, multiply by 0.0929. To convert to square yards, divide by 9. This calculator does all those conversions automatically.
When you need square footage
Buying flooring: Carpet, hardwood, vinyl, and tile are all sold by the square foot or square yard. Always add 5–10% to your measured area to account for cuts, pattern matching, and waste.
Painting walls: Calculate the wall area as perimeter × ceiling height. A gallon of paint typically covers 350–400 square feet, so a 12 × 14 ft room with 8 ft ceilings (416 sq ft of wall) needs roughly one gallon for one coat.
Comparing homes: Real estate listings quote total square footage as a way to compare value across properties. Cost per square foot (price ÷ sq ft) is a common shorthand for whether a home is fairly priced for its market.
Measuring land: Plot sizes are often given in square feet for smaller lots and acres for larger ones. One acre = 43,560 square feet.
Typical room and house sizes
For context when planning or budgeting:
- Bedroom: 100–200 sq ft
- Master bedroom: 200–350 sq ft
- Bathroom: 40–100 sq ft
- Kitchen: 150–300 sq ft
- Living room: 200–400 sq ft
- Two-car garage: 400–500 sq ft
- Average new US single-family home: 2,300–2,500 sq ft
FAQs
For a rectangular room, multiply the length by the width — both measured in feet. For example, a room 12 feet long and 10 feet wide is 12 × 10 = 120 square feet. For other shapes, use the appropriate area formula: ½ × base × height for triangles, π × radius² for circles, and ½ × (a + b) × height for trapezoids.
Use a tape measure to record the length and width of each wall in feet. Round to the nearest inch for accuracy and convert inches to a decimal of a foot (e.g. 6 inches = 0.5 feet). Multiply length by width for rectangular rooms. For irregularly shaped rooms, divide them into smaller rectangles, calculate each one separately, and add the results together.
Either convert your inch measurements to feet first by dividing by 12, or multiply the inches together and then divide by 144 (since 1 sq ft = 144 sq in). For example, a tile 18 inches × 12 inches has an area of 216 sq in, which equals 1.5 sq ft.
Square feet measure area (a two-dimensional surface), while linear feet measure length (a one-dimensional distance). A 10-foot wall is 10 linear feet, but if it is 8 feet tall it has 80 square feet of surface area. Linear feet are used for measuring trim, fencing, or pipe; square feet are used for flooring, paint, and land area.
The average new single-family home built in the United States is around 2,300–2,500 square feet, though this varies considerably by region and decade. The average existing home is closer to 1,800 square feet. For comparison, a typical bedroom is 100–200 sq ft, a master bedroom 200–350 sq ft, and a two-car garage 400–500 sq ft.
For flooring, calculate the floor area as length × width and add 5–10% for cuts and waste. For paint, calculate the wall area (perimeter × ceiling height) and subtract the area of doors and windows. One gallon of paint typically covers 350–400 square feet with one coat.