How To Calculate The Square Footage Of A Home

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Knowing how to calculate the square footage of a home is important for real estate investors. Whether you’re looking to buy or sell a property, renovate an existing one, or need to measure a rental property’s rooms for furniture placement, you need to know how to calculate the square feet you’re working with. 

This article will explore why calculating square footage is important and how to do it. 

Why Calculating Square Footage is Important

A square foot is a measured amount of flat space that covers an area. Its measurement is one foot x one foot (or 12 inches * 12 inches, equaling 144 square inches), meaning that if you have a 100-square-foot bedroom, you can divide it into 100 equal squares.

Regardless of your reasoning, you need to know how to calculate square feet down to the foot. Being off by even a little bit can cost you hundreds—even thousands of dollars. Here are a few reasons why:

• Identifying fair market value: Square footage is a key indicator of a property’s fair market value. When selling a house, you need to know what comparable homes in your area are worth. If the average home price per square foot in your neighborhood is $200 and your measurements are off by 10 feet, you could undervalue your property by $2,000.
• Tax assessments: If you believe the assessed value of your property is too high, you can calculate the square footage to see if your number matches the assessors. You can dispute the assessment and save money on property taxes if your number is lower.
• Renovations: If you’re renovating your home or a rental property, you need to calculate the square footage of the areas you’re rehabbing. This calculation will let you know how much material to buy and ensure your new furniture and appliances will fit and function properly. 

How to Calculate Square Footage

You can measure square footage with just a few basic supplies:

• Tape measurer
• Paper and pencil
• Calculator

Start by sketching your space and label every room you have to measure. Mark hallways, foyers, and vestibules as their own rooms. If your property has more than one story, sketch out each individual floor. Your sketch doesn’t have to be perfectly proportionate, but the more accurate you are, the better.

Next, measure the length and width of each room, and multiply these numbers together. For example, if your master bathroom is 10 feet long and 15 feet wide, its square footage is 150 feet. Record the length, width, and total for each room you measure. 

After measuring every room, add all the measurements to get your property’s total square footage. 

Calculating Square Footage in Different Types of Rooms

In a dream scenario, your property is either a perfect square or a rectangle with no additional calculations or omissions required. For most properties, this is not the case. 

Rooms with closets or immovable fixtures

Some closets and fixtures are built to fit the contours of a room. These will require you to divide the room into distinct areas you’ll need to work around, especially when installing new flooring. Treats these are separate entities and take individual measurements of each. Next, calculate the overall square footage of the room, including the closets and immovable fixtures, then subtract them from the total square footage to identify how much space you’re working with. 

Rooms with odd shapes

Not every room is a square or rectangle. Rooms with unique shapes can pose a challenge when you’re trying to determine their square footage. It’ll likely be inaccurate if you try to measure the area with a single computation. You need to be as precise as possible. 

The simplest method to measure these rooms is to divide them into regular shapes. You probably won’t be able to break each area into squares and rectangles, but you should be able to divide it into easily measurable shapes, like triangles. After dividing up the room and getting the square footage of each shape within it, add all of them to identify the total square footage. 

What is Usable Square Footage?

Simply put, usable square footage is how much space you have to use. This includes all of the floor space available within your walls. If you can put flooring down on it, like carpet, tile, or hardwood, it’s usable square footage. 

What Not to Include in Your Calculations

Not all of your property’s interiors are included in your square footage. When taking measurements, omit areas you can’t walk or live in. For example, don’t include your crawl space in your square footage calculations.

Here’s what’s commonly excluded:

• Garages: While you can use them for storage and car parking, people don’t usually live in them. 
• Basements: Even when finished, basements are often excluded because they’re considered below grade (below ground level). However, some states will consider it as part of your overall square footage if you can enter and exit it safely.
• Attics: Unfinished attics aren’t calculated in your property’s square footage. However, they may be included in your total square footage if they are finished and meet certain regulations (e.g., minimum ceiling heights). 

Conclusion

When ordering flooring materials, leave yourself room for error by ordering 10% more than you need. For example, if you’re retiling your 100-square-foot kitchen floor, order 110 square feet worth of tile. It won’t cost much more, but it can save you from a major headache.

A professional appraiser or flooring expert will charge you a few hundred for this service but can save you much more than that if you’re wrong. Also, even if you’ve carefully calculated your home’s total square footage, it never hurts to ask a professional to double-check your work—especially if your property has oddly shaped rooms and immovable fixtures. If you want peace of mind and the job done right, check out our contractors page and find an expert near you.

Note By BiggerPockets: These are opinions written by the author and do not necessarily represent the opinions of BiggerPockets.