Content of the material
- How to calculate square footage
- Tools needed to measure square footage
- How much to allow for waste?
- How many square feet is a 12×12 room?
- How to find the square footage of a circle
- Why Tenants, Homeowners, and Landlords Need to Know Square Footage
- Top Articles
- How to calculate how many pieces of bullnose you will need?
- How to calculate the square feet of a house
- How to quickly estimate square footage
- Use your body
- Use tiles
- Visualize comparative spaces
- What is Usable Square Footage?
- Jason Somers, President & Founder of Crest Real Estate
- Methods for how to calculate square feet for different shapes
- How to calculate square feet for squares and rectangles
- How to calculate square feet for triangles
- How to calculate square feet for circles
- How to calculate square feet for trapezoids
- How to calculate square feet for rhombuses
- How to calculate square feet for parallelograms
- When in doubt, ask the pros
- Learn more:
How to calculate square footage
Calculating square footage is, luckily, pretty simple. You just multiply the length of a room or house in feet by the width in feet.
The basic formula for square feet:
Length x Width = total area square footage
Unfortunately, that equation only applies to rooms and homes that are rectangular or square. If your home has any odd-shaped rooms, things get a lot more complicated.
It seems like a straightforward question: How do you calculate square footage in your home?
Unfortunately, the answer isn’t as straightforward as you’d think. For different purposes (like sale listings) states regulate what parts of a home should be measured, and what parts shouldn’t. Here’s what you need to know.
The below methods and tips will work well if you have all or mostly rectangular rooms. If you have any more complex spaces and you aren’t particularly skilled in math, we recommend leaving the square footage calculation to an expert (like an appraiser), or consulting your home’s floor plan.
Tools needed to measure square footage
There are a few different ways you can measure your square footage.
- Something to take notes (either a pen and paper, or a phone or other device with a notepad app);
- A tape measure or laser measuring tool.
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 many square feet is a 12×12 room?
The square footage of a room measuring 12 feet wide by 12 feet long is 144 square feet. To calculate this you simply multiply the width by the height. 12ft × 12ft = 144 sq ft.
How to find the square footage of a circle
- Measure the diameter of your circle in feet.
- Divide your diameter by 2 and then square it (multiply it by itself).
- Multiply your total by π (3.14159265)
The formula for calculating the area of a circle is: π r2 (with r being the radius of the circle, which is half the diameter). π is the symbol for pi (3.14159265).
Why Tenants, Homeowners, and Landlords Need to Know Square Footage
There are several reasons why tenants, homeowners, and landlords should all know how to calculate square feet:
- Knowing the square footage of a room can help you confirm if your furniture will fit.
- Knowing the square footage of a specific surface can help you estimate renovation costs. If you’re replacing a kitchen countertop, for example, you need to calculate the square footage of the countertop so you can get accurate quotes for the cost of the job.
- When you know how to calculate square feet, you can make sure you order the right amount of supplies and materials. If, for example, you plan to paint a wall that’s 12 feet long by 10 feet tall, you need to find the total square footage so you know how much paint to buy.
- Perhaps most importantly, knowing the square footage of homes and apartments helps you compare prices to find the best value. Let’s say you’re deciding between two similar apartments: Apartment A is $1,500 per month and Apartment B is $1,800 per month. Which is the better deal? Well, it depends on the square footage. If Apartment A is 500 square feet and Apartment B is 1,000 square feet, you’re getting more space for your money with Apartment B.
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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.
How to calculate the square feet of a house
When preparing to measure the square footage of a home, be it a house, condo, or townhouse, start with a few simple supplies:
- Paper and pencil
- Measuring tape and/or laser measuring tool
If the property is a perfect rectangle, simply measure the length and width and multiply those two numbers together. For example, if your one-story house is 60 feet wide by 40 feet long, then your property is 2,400 square feet (60 x 40 = 2,400).
However, most properties have more complex floor plans. When this is the case, it’s helpful to follow these simple steps to measure square footage.
- Draw a rough sketch of your entire space, labeling all of the rooms you need to measure. Include hallways and vestibules as their own “room.”
- Measure the length and width, in feet, of each room. Then, multiply the length by the width to calculate that room’s square footage. For example: If a bedroom is 12 feet by 20 feet, it is 240 square feet (12 x 20 = 240). For each room, write the total square footage in the corresponding space on your sketch.
- Once each room is measured, add up all the measurements to determine your home’s total square footage.
Note: If you live in a tract home, condo or townhome community, you may be able to get architectural drawings or master builder plans of your floor plan. These may already have your square footage calculated.
How to quickly estimate square footage
Sometimes, you might need to estimate or visualize square footage without being able to measure it exactly. This is an especially useful skill if you’re shopping for a home or apartment. Here are some tips, tricks, and examples for making square footage estimates in the real world.
Use your body
One way to get a rough estimate of the width and length of a space is by using your own body. Measure body lengths to use your height. Or measure the length of your foot and walk heel-to-toe to measure the distance. You can also measure the length of your stride, but this will result in a less accurate measurement, since it will vary a little bit with each step.
If the room you’re trying to estimate has tiles on the floor, you can use them to get an estimate of the square footage by assuming that each tile will be around one square foot. Remember that tiles can be larger or smaller than this, though, so your accuracy may vary with this method depending on how close the tiles are to 12 inches.
Visualize comparative spaces
If you don’t need an exact number, but just a rough guess of the square footage of a space, you can compare it to items or other spaces you might be familiar with. For example,
- A king size bed is 42.15 square feet.
- The inside of a school bus is about 300 square feet.
- A one-car garage is about 200 square feet, while a two-car garage will be around 400 square feet.
What is Usable Square Footage?
If you’re involved in commercial real estate in any way, you may have heard the term “usable square footage”. This term describes the total amount of square footage that a tenant is able to use, which excludes areas like hallways, stairwells, and lobbies. When it comes to residential real estate, the usable square footage in your home refers to the amount of space that would count as your personal space.
Common areas like kitchens, living rooms, hallways, and storage closets wouldn’t count as usable square footage. With this information in hand, you should be able to calculate the actual square footage of your home as well as the usable square footage of your home.
Being able to calculate the square footage of you home can be very helpful when you’re attempting to sell your property or would like to complete a renovation. If you’re getting ready to renovate your entire kitchen, knowing the square footage of the floor will allow you to purchase the right amount of materials. Keep in mind that most flooring materials are priced by square feet.
Let’s say that hardwood flooring has a price of $10 per square foot. If your kitchen has a floor space of 175 square feet, the flooring would likely cost around $1,750. In the event that you work as an architect or structural engineer, knowing how to calculate the square footage of a space can be invaluable for your work.
Jason Somers, President & Founder of Crest Real Estate With over 15 years of professional experience in the Los Angeles luxury real estate market, Jason Somers has the background, judgement and track record to provide an unparalleled level of real estate services. His widespread knowledge helps clients identify and acquire income producing properties and value-ad development opportunities. Learn more about Jason Somers or contact us.
Methods for how to calculate square feet for different shapes
Different shapes have different ways of calculating square footage. For all the shapes, it may be helpful to convert the measurement of the shape into square feet before making your calculation. Converting the measurements can help you keep the shape to scale, especially if the sides have different measurements, such as feet and inches or yards and meters. You could also perform the calculation and then convert the final measurement to square feet to achieve the same result.
Use the methods below to help you calculate square feet for seven different shapes:
How to calculate square feet for squares and rectangles
Squares and rectangles use the same formula to calculate square feet. This formula is:
A = length x width
In this equation, "A" is the total area of the shape in square feet. The length is the measurement of one side of the shape in feet and the width is the measurement of another side of the shape in feet. You can use the steps below to calculate the square footage of squares and rectangles with the formula above:
If necessary, convert your measurements for each side of the shape into feet.
Multiply the length and the width of the shape together to get the area of the square or rectangle in square feet.
How to calculate square feet for triangles
The square footage formula for triangles is:
A = 1/2 base x height
In this equation, "A" is the area of the triangle in square feet, "1/2 base" is the length of the bottom side of the triangle in feet and the height is the vertical distance from the bottom side of the triangle to the top corner in feet. You can use the following steps to calculate the area of a triangle:
Convert the measurements for the base and height into feet.
Divide the length of the base by two to get half of the base.
Multiply half the base by the height to find the square footage area of the triangle.
How to calculate square feet for circles
To calculate the area of a circle, it's necessary to use the number pi, which is represented by the symbol π. You can use the decimal 3.14 to represent the value of pi. The formula to calculate the square footage of a circle is:
A = π x radius2
In this equation, "A" is the total square footage, π is equal to 3.14 and the radius is the distance from the exact center of the circle to the outside edge in feet. To calculate the area of a circle, use the following steps:
If it isn't already in feet, convert the measurement for the radius into feet.
Multiply the length of the radius by itself to get feet squared.
Once you've calculated the square feet of the radius, multiply that result by pi to get the total area of the circle in square feet.
How to calculate square feet for trapezoids
To calculate the square footage of a trapezoid, you can use the formula:
A = [(base length + top length) / 2] x height
In this equation, "A" is the total area of the shape in square feet. The base length is the length of the bottom of the trapezoid in feet, and the top length is the length of the top of the trapezoid in feet. The height is the vertical distance from the base length to the top length of the trapezoid in feet. You can use the following steps to calculate the area of a trapezoid:
If necessary, convert the measurements for the base length, top length and height into feet.
Add the base length and the top length together to calculate the area for the nonrectangular sections of the trapezoid created by the diagonal sides.
Divide the sum of the base length and the top length by two to ensure you account for the diagonal sides in the equation.
Multiply that result by the height to find the area of the trapezoid in square feet.
How to calculate square feet for rhombuses
To calculate the square footage of a rhombus, you can use the following formula:
A = distance from one pair of opposite angles x distance from the other pair of opposite angles
In this equation, "A" is the area of the rhombus in square feet and the distances from both pairs of opposite angles are in feet. You can calculate the area of a rhombus using the following steps:
Convert the measurements for the distances of the rhombus into feet if necessary.
Multiply the interior lengths, which are the distances from opposite angles within the rhombus, to find the area in square feet. The interior lengths intersect with each other at the center of the shape.
How to calculate square feet for parallelograms
To calculate the square footage of a parallelogram, you can use the formula below:
A = base x height
In this equation, "A" is the area of the parallelogram in square feet, the base is the length of the bottom side of the parallelogram in feet and the height is the vertical distance from the base of the parallelogram to the top side in feet. You can calculate the square footage of a parallelogram using the steps below:
If necessary, convert the measurements for the base and height into feet.
Multiply the base by the height of the parallelogram to find its area in square feet.
When in doubt, ask the pros
If calculating the square feet of your particular property feels overwhelming, consider hiring a professional appraiser to do it. The average appraisal cost for a single-family home typically runs about $350. A condo appraisal fee is generally between $300 and $500, and multi-family home appraisals can run anywhere from $600 to $1,500.
While two different professional appraisers could evaluate the same home and come up with slightly different square footage figures, they do all aim for scientific accuracy. “We’re always shooting for somewhere between 1 to 3 percent variance,” Day says.
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