Square Footage Calculator
Need to know how much space you actually have? Enter the dimensions of your area and calculate the square footage instantly.
This square footage calculator is useful for rooms, floors, patios, decks, walls, yards, storage areas, and other spaces where you need to turn measurements into an area. You can work with straightforward rectangular measurements, or break a more complicated space into smaller sections and combine the results.
Square Footage Calculator
Calculate square feet from room dimensions, combine multiple areas, subtract sections, and estimate the material area you may need.
Area breakdown
What Does Square Footage Mean?
Square footage is a measurement of area. It tells you how much two-dimensional surface is inside a particular boundary.
One square foot is a square that measures 1 foot by 1 foot.
So if a rectangular room is 10 feet long and 14 feet wide, its floor area is:
10 × 14 = 140 sq ft
Square footage is commonly used when measuring:
Bedrooms and living rooms
Kitchens and bathrooms
Floors and flooring areas
Patios and decks
Garages
Walls
Lawns and landscaping areas
Construction surfaces
Apartments and homes
Storage and workshop spaces
The important part is that the measurements must describe the same area and use compatible units.
How to Calculate Square Feet
For a rectangular space, measure the length and width and multiply them.
The formula
Area = Length × Width
If the measurements are already in feet:
Square feet = Length in feet × Width in feet
Example
Suppose your room is:
Length: 18 ft
Width: 13 ft
Then:
18 × 13 = 234 sq ft
The room has 234 square feet of floor area.
This same approach works for a rectangular floor, patio, deck, garden section, garage, or other flat area.
What If My Measurements Include Inches?
This is one of the easiest places to make a mistake.
An inch measurement is not converted to a decimal by simply moving the decimal point. Instead, convert the inches to a fraction of a foot.
There are 12 inches in 1 foot, so:
Decimal feet = inches ÷ 12
For example:
3 inches = 0.25 ft
6 inches = 0.50 ft
9 inches = 0.75 ft
Example: 12 ft 6 in × 10 ft
First convert 12 ft 6 in:
6 ÷ 12 = 0.5 ft
So:
12 ft 6 in = 12.5 ft
Then:
12.5 × 10 = 125 sq ft
The area is 125 square feet.
A measurement of 12 ft 6 in should therefore be treated as 12.5 feet, not 12.6 feet.
How to Measure a Room for Square Footage
A calculator can only be as accurate as the measurements you enter. For a typical room, a tape measure and a few careful checks are enough.
1. Measure the length
Measure from one finished wall to the opposite wall.
2. Measure the width
Take the measurement perpendicular to the length.
3. Record the units
Write down whether your measurements are in feet, inches, meters, or another unit.
4. Enter the dimensions
Enter the measurements into the calculator and check the resulting area.
5. Check unusual sections
If the room contains an alcove, bump-out, closet, bay, or other section that changes its shape, treat that section separately rather than forcing the entire room into one rectangle.
For a normal rectangular room, this gives you the basic floor area.
How to Calculate an Irregular Room
Not every room is a perfect rectangle.
An L-shaped room, for example, can usually be divided into two rectangles. Calculate each rectangle separately and then add them together.
Example
Imagine an L-shaped space made from:
Section A:
12 ft × 15 ft = 180 sq ft
Section B:
6 ft × 8 ft = 48 sq ft
Add them:
180 + 48 = 228 sq ft
So the total area is 228 square feet.
The same principle can be used for larger floor plans: divide the shape into manageable sections, calculate each section, and add the areas.
For a more complicated shape, make sure the sections do not overlap. Otherwise, part of the space could accidentally be counted twice.
Square Footage for Flooring
When ordering flooring, the calculated room area is usually the starting point rather than the exact amount you should purchase.
Cuts, offcuts, damaged pieces, pattern matching, and installation waste can mean that you need more material than the measured floor area.
For example, if your measured area is:
400 sq ft
and you decide to allow 10% extra:
400 × 1.10 = 440 sq ft
You would plan around 440 sq ft of material.
The appropriate allowance depends on the material, installation pattern, room shape, and how many cuts are required. Straightforward rectangular rooms may need less extra material than spaces with many corners or complex patterns.
Do not confuse the measured area with the amount you need to purchase.
Square Footage vs. Square Meters
Square feet and square meters both measure area, but they are different units.
Useful conversions include:
1 square foot ≈ 0.092903 square meters
1 square meter ≈ 10.7639 square feet
So a space measuring 200 sq ft is approximately:
200 × 0.092903 = 18.58 m²
This is useful when your room dimensions are measured in feet but the product you are buying is listed in square meters, or vice versa.