How to Calculate Square Footage
Need to know how many square feet a room, house, floor, or other space has? Calculating square footage is usually simple when you know the length and width of the area.
The basic formula is:
Square Footage = Length × Width
For example, a rectangular room that is 12 feet long and 10 feet wide has:
12 × 10 = 120 square feet
For irregular spaces, you can divide the area into smaller rectangles or other simple shapes, calculate each section separately, and then add the results together.
If you want to calculate an area automatically, use our Square Footage Calculator.
What Is Square Footage?
Square footage is a measurement of area commonly used in the United States to describe the size of rooms, homes, apartments, offices, floors, and other spaces.
One square foot represents a square measuring:
1 foot × 1 foot = 1 square foot
For example, an area measuring 10 feet by 10 feet has:
10 × 10 = 100 square feet
So the area is 100 sq ft.
How Do You Calculate Square Footage?
The basic square footage formula is:
Square Footage = Length × Width
To calculate the square footage of a rectangular or square area:
- Measure the length in feet.
- Measure the width in feet.
- Multiply the length by the width.
- The result is the area in square feet.
Example
Suppose a bedroom is:
- Length = 14 feet
- Width = 12 feet
Calculation:
14 × 12 = 168 square feet
The bedroom is therefore 168 square feet.
How to Calculate Square Footage of a Room
Calculating the square footage of a standard rectangular room is straightforward.
Formula
Room Area = Length × Width
For example, if your living room is 20 feet long and 15 feet wide:
20 × 15 = 300 sq ft
Your living room has 300 square feet of floor area.
What If the Measurements Are in Inches?
Convert inches to feet first.
There are 12 inches in one foot.
For example:
144 inches ÷ 12 = 12 feet
Then use the standard square footage formula.
How to Calculate Square Footage of an Irregular Room
Not every room is a perfect rectangle. L-shaped rooms, hallways, extensions, and other irregular spaces require an additional step.
The easiest method is to divide the space into smaller rectangular sections.
Example
Suppose an irregular room can be divided into two rectangles.
Section A:
10 ft × 12 ft = 120 sq ft
Section B:
8 ft × 6 ft = 48 sq ft
Now add the two areas:
120 + 48 = 168 sq ft
The total area is therefore 168 square feet.
This method can be used for many irregular floor plans.
How to Calculate Square Footage of a House
For a house with multiple rectangular rooms, calculate each room separately and then add the areas together.
For example:
| Room | Length | Width | Area |
|---|---|---|---|
| Living Room | 20 ft | 15 ft | 300 sq ft |
| Bedroom | 14 ft | 12 ft | 168 sq ft |
| Kitchen | 12 ft | 10 ft | 120 sq ft |
| Bedroom 2 | 12 ft | 11 ft | 132 sq ft |
Total:
300 + 168 + 120 + 132 = 720 sq ft
The combined area of these rooms is 720 square feet.
When calculating an entire home's square footage, make sure you understand which areas should be included according to the measurement standard or purpose of the calculation.
How to Calculate Square Footage From Inches
If your measurements are in inches, you can convert them to feet before calculating.
Since:
1 foot = 12 inches
For example:
- Length = 144 inches
- Width = 120 inches
Convert both measurements:
144 ÷ 12 = 12 feet
120 ÷ 12 = 10 feet
Then calculate:
12 × 10 = 120 sq ft
Direct Formula Using Inches
If both dimensions are measured in inches, you can use:
Square Feet = Length in Inches × Width in Inches ÷ 144
For example:
144 × 120 ÷ 144 = 120 sq ft
How to Calculate Square Footage From Meters
If your measurements are in meters, first calculate the area in square meters.
Area = Length × Width
Then convert square meters to square feet.
1 square meter ≈ 10.7639 square feet
Example
Suppose an area is:
- Length = 5 meters
- Width = 4 meters
First calculate the area:
5 × 4 = 20 m²
Then convert:
20 × 10.7639 ≈ 215.28 sq ft
So the area is approximately 215.28 square feet.
How to Calculate Square Footage for Flooring
Square footage is commonly used when estimating the amount of flooring material needed for a room.
First calculate the floor area:
Length × Width = Floor Area
Example
Suppose a room measures:
- Length = 20 feet
- Width = 15 feet
The floor area is:
20 × 15 = 300 sq ft
When purchasing flooring, you may need additional material to account for cuts, installation patterns, and waste.
For example, with a 10% allowance:
300 × 1.10 = 330 sq ft
You would therefore plan for approximately 330 square feet of flooring material.
The appropriate waste allowance depends on the flooring material, room shape, installation pattern, and installer.
How to Calculate Square Footage for Paint
Calculating wall surface area is different from calculating floor area because you also need the wall height.
For a rectangular room:
Wall Area = Room Perimeter × Wall Height
Example
Suppose a room is:
- Length = 12 ft
- Width = 10 ft
- Wall height = 8 ft
First calculate the perimeter:
2 × (12 + 10) = 44 ft
Then calculate the wall area:
44 × 8 = 352 sq ft
The total wall surface area is 352 square feet before subtracting doors and windows.
If you are estimating paint, you can subtract the square footage of doors, windows, or other areas that will not be painted.
Common Square Footage Formulas
Different shapes require different area formulas.
Rectangle
Area = Length × Width
Square
Area = Side × Side
Triangle
Area = ½ × Base × Height
Circle
Area = π × Radius²
For an irregular space, divide the area into smaller shapes, calculate each shape separately, and then add the results.
Square Footage vs. Square Feet
The terms square footage and square feet are closely related but have slightly different uses.
- Square foot (sq ft or ft²) is a unit of area.
- Square footage refers to the amount of area measured in square feet.
For example:
The house has 2,000 square feet.
You might also hear:
The house has 2,000 square feet of living space.
Both expressions are commonly used when discussing property size.
Why Is Square Footage Important?
Square footage is useful for many everyday calculations and decisions.
It can help you estimate:
- Flooring requirements
- Carpet requirements
- Tile requirements
- Paintable wall area
- Room size
- Home size
- Construction materials
- Landscaping areas
- Property dimensions
- Heating and cooling requirements
- Material costs
Knowing the area of a space makes it easier to estimate how much material you need and compare different spaces.
Use Our Square Footage Calculator
You don't always need to calculate square footage manually.
Our Square Footage Calculator can quickly calculate the area of common shapes and spaces.
Enter your measurements, select the appropriate units, and the calculator can provide the square footage.
Square Footage Examples
Here are some common examples.
10 × 10 Room
10 × 10 = 100 sq ft
12 × 12 Room
12 × 12 = 144 sq ft
15 × 20 Room
15 × 20 = 300 sq ft
20 × 30 Room
20 × 30 = 600 sq ft
25 × 40 Area
25 × 40 = 1,000 sq ft
The same length × width formula works for any rectangular area as long as both measurements use the same unit.
How to Calculate Square Footage Step by Step
If you are measuring a rectangular space manually, follow these steps:
Step 1: Measure the Length
Use a tape measure to determine the longest dimension of the area.
Record the measurement in feet if possible.
Step 2: Measure the Width
Measure the other dimension perpendicular to the length.
Step 3: Check Your Units
Make sure both measurements use the same unit.
For example, don't multiply feet by inches without converting first.
Step 4: Multiply
Use:
Length × Width = Square Footage
Step 5: Round When Appropriate
For material estimates, you may want to allow some additional material for cutting and waste.
Common Mistakes When Calculating Square Footage
1. Mixing Units
Don't multiply feet by inches without converting the measurements.
Convert everything to the same unit first.
2. Forgetting Irregular Sections
An L-shaped room cannot always be calculated correctly using only its maximum length and maximum width.
Divide it into smaller sections.
3. Confusing Linear Feet With Square Feet
Linear feet measure length.
Square feet measure area.
For example:
10 linear feet is a length measurement, while 100 square feet is an area measurement.
4. Forgetting Doors and Windows
When estimating paintable wall area, doors and windows may need to be subtracted.
5. Not Allowing for Material Waste
Flooring, tile, roofing, and other materials may require additional material because of cuts and installation waste.
Frequently Asked Questions
How do you calculate square footage?
For a rectangular area, multiply the length by the width.
Square Footage = Length × Width
Both measurements should be in the same unit, preferably feet when calculating square feet.
How is square footage calculated?
Square footage is calculated by measuring the dimensions of an area and applying the appropriate area formula. For a rectangle, multiply length by width.
How do you calculate the square footage of a room?
Measure the room's length and width in feet and multiply them.
For example:
12 ft × 10 ft = 120 sq ft
How many square feet is a 10 × 10 room?
A 10-foot by 10-foot room has:
10 × 10 = 100 square feet
How many square feet is a 12 × 12 room?
A 12-foot by 12-foot room has:
12 × 12 = 144 square feet
How do I calculate square footage from inches?
Multiply the length in inches by the width in inches and divide by 144.
Square Feet = Length × Width ÷ 144
How do I calculate square footage of an irregular area?
Divide the irregular area into smaller rectangles, triangles, or other simple shapes. Calculate the area of each section and add the results.
How many square feet are in one square meter?
One square meter is approximately:
10.7639 square feet
What is the formula for square footage?
For a rectangle:
Square Footage = Length × Width
For other shapes, use the appropriate area formula.
Final Answer
For most rectangular spaces, calculating square footage is simple:
Length × Width = Square Footage
If the space is irregular, divide it into smaller sections, calculate each section, and add the areas together.
For quick calculations, use our Square Footage Calculator.