Content of the material
- How to calculate square feet
- How many square feet is a 20×20 room?
- What to leave out
- How to Calculate Square Footage of Spaces of Different Shapes
- Rectangular and Square Spaces
- Circular Spaces
- Triangular Spaces
- Convert among square inch, square foot, square yard and square meter
- How to calculate how many pieces of bullnose you will need?
- What is square footage used for?
- How much to allow for waste?
- How to Calculate the Square Feet of a Home or Residence
- How to Calculate Price per Sq Ft
- Convert Inches to Feet
How to calculate square feet
To calculate an area in square feet, you will need measurements for the width and length (for a square shape) or the diameter (for a circular area). It may be that the area you're looking to measure is a strange shape (such as a room or garden). In this case, dividing it up into smaller parts and doing individual calculations is a good way to calculate the overall square footage.
Let's say you have a rectangular-shaped room and you want to calculate the square footage area for flooring or carpet. The easiest method for calculating the square footage is to measure the length and width in feet and then multiply the two figures together to give you a result in ft2. If you're measuring a room for flooring, take a look at our article on how to measure for a new floor.
Should you find yourself needing to calculate an area of square feet in an 'L' shape, consider dividing the shape up into rectangular sections and treating them as separate areas for calculation (adding them together at the end). For more instructions, see our full article: how to calculate square footage.
How many square feet is a 20×20 room?
The square footage of a room measuring 20 feet wide by 20 feet long is 400 square feet. To calculate this you simply multiply the width by the height. 20ft × 20ft = 400 sq ft.
What to leave out
A good rule of thumb to ensure you’re taking proper measurements is to exclude space you can’t walk on or live in. These types of spaces do not count as “gross living area.”
“Someone might think, ‘If I get the measurement of my first floor and I have a two-story house, I just multiply that by two,’” Day says. However, if that first floor includes a two-story foyer, you can’t count the non-usable space.
Basements and garages, even if they are finished, don’t generally count toward total square footage. Basements are typically excluded because they are built below grade, meaning below ground level. If your state does allow basements to be included in the total square footage of a home, though, you’ll likely need an ingress and egress, or a safe way to enter and exit the basement to the outside.
Finished attic spaces — with some regulations, including ceiling heights — can count toward the total square footage of your home. If you are planning to sell your home, work with a real estate agent to craft a listing that accurately reflects your property.
How to Calculate Square Footage of Spaces of Different Shapes
The square footage formula depends on the shape of the space. Here are the formulas for some common shapes:
Rectangular and Square Spaces
Formula: Area = l x w
Plug your measurements in for length and width and calculate as described above.
Formula: Area = πr2
Measure the radius, which is the distance from the midpoint of the space to the edge. The radius is half the diameter — or the length of a straight line that passes through the center of the circle.
Next, square the radius and multiply it by pi (π), or 3.14.
Formula: Area = ½bh
This formula works with right triangles, which have one 90-degree angle. If your space isn’t already a right triangle, break it into two right triangles for the purposes of measuring.
For each right triangle, multiply the lengths of the straight sides — the base and height. Then, divide by two. With multiple triangles, add the values for the total square footage.
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Convert among square inch, square foot, square yard and square meter
You could, for example, perform all of your measurements in inches or centimeters, calculate area in square inches or square centimeters then convert your final answer to the unit you need such as square feet or square meters.
To convert among square feet, yards and meters use the following conversion factors. For other units use our calculator for area conversions.
- Square Feet to Square Inches
- multiply ft2 by 144 to get in2
- Square Feet to Square Yards
- multiply ft2 by 0.11111 to get yd2
- Square Feet to Square Meters
- multiply ft2 by 0.092903 to get m2
- Square Yards to Square Feet
- multiply yd2 by 9 to get ft2
- Square Yards to Square Meters
- multiply yd2 by 0.836127 to get m2
- Square Meters to Square Inches
- multiply m2 by 1,550 to get in2
- Square Meters to Square Feet
- multiply m2 by 10.7639 to get ft2
- Square Meters to Square Yards
- multiply m2 by 1.19599 to get yd2
How to calculate how many pieces of bullnose you will need?
If you have ten feet exposed edge that needs bullnose this is equal to 120″. If you selected a 6″ bullnose or trim piece, you will need to divide 120″ by 6″, which will give you 20 pieces of bullnose needed. Using 8″ decorative liner for the same 120″, you divide 120″ by 8″ which would be 15 pieces of liner needed.
What is square footage used for?
You can use square footage in real-world contexts such as:
Architecture: Architects use square footage to measure the space that a building or other construction projects may fill.
Cartography: Cartographers use square footage to determine the area that countries and other landmarks might occupy on a map or globe.
Landscaping: Landscapers use square footage to find how much space a yard or other plot of land takes and what can fit within that space.
Real estate: Realtors and contractors use square footage to describe how much floor space a house or other marketable building has when it's for sale.
You can also use square footage as the first step toward calculating cubic footage, or the volume of an area. For example, you can use the outcome of the calculation and multiply the number by the width of a shape. If the measurements are in feet, then you get a cubic measurement. This means there are three sides you measure to get the volume of the shape.
Related: Top Skills Required for Landscaping
How much to allow for waste?
To allow for waste, you must consider the installation. For most standard installations, 10% extra for waste is sufficient. Percentage of waste for more elaborate patterns like running tile on a 45 degree angle, herringbone or cross hatch, consult with your installer. Add 15% for tile being installed in a room with lots of jogs and corners. These installations will require more cuts and thus more waste.
Length x Width + Waste = Amount Needed
How to Calculate the Square Feet of a Home or Residence
When measuring the square footage of a home or residence, some special considerations apply to determine the inhabitable square footage. The livable size of a home helps determine the market value and price and helps buyers understand the overall size.
Only livable rooms, with finished walls, floor, and ceiling, count toward the finished area of the home. For a room to be considered livable, the space should be finished and should have heating or air conditioning as applicable.
Indoor spaces count toward the square footage of a home, while outdoor spaces typically do not. In fact, the American National Standards Institute has defined rules for what counts as finished area and which rooms contribute to the gross living area of a home.
To calculate the total area, measure each room in feet using a tape measure. Then, multiply the length and width of each room to get the square footage, then add them all together.
The calculator above can help determine the square feet of each room, then simply add all the room’s areas together. We also have great resources on how to measure rooms and complex spaces.
How to Calculate Price per Sq Ft
To calculate the price per square foot of your home, divide the total price by the number of square feet.
price per ft2 = total price ÷ total ft2
For example, to find the price per ft2 of a home that costs $200,000 and is 2,000 ft2 use this formula.
price per ft2 = $200,000 ÷ 2,000 ft2 price per ft2 = $100
If you’d prefer not to do the math, you can also use our unit price calculator to calculate the price per square foot.
Convert Inches to Feet
You may need to convert inches to feet for certain projects. To do so, divide the total number of inches by 12. To get from feet to inches, multiply by 12.
Since we’re all home now more than ever, being prepared for unexpected home repairs with a plan from HomeServe is important. Having a plan in place gives you the peace of mind knowing that you can simply call our 24/7 repair hotline for covered breakdowns. See what plans are available in your neighborhood.