Whether you are buying or selling your home or renovating it, it is essential to understand how to calculate your square feet in your home. Area determines the value of the property, tax valuation, and even the amount of flooring and paint required. However, measuring the size of a home is not as easy as it looks. Some areas count towards total area area, but others, such as garages and unfinished basements, may not. For example, cities like San Francisco and Chicago can affect what local building codes count as livable spaces.
This Redfin guide explains how to accurately measure area and answers general questions such as “Is the garage included in the area?”
How is the size of a house calculated?
Square footage is usually measured according to ANSI (American National Standards Institute) guidelines. This provides a standardized method of calculating home size. The ANSI method requires measuring the exterior dimensions of the home, including all completed, habitable spaces.
How does this work:
Measure the exterior: Experts measure from the exterior walls and calculate the total total area. Wall thickness is included in the total, but not subtracted. Include completed areas: Counts heated, livable space that meets height and accessibility requirements. This includes the main living area, bedrooms, bathrooms and an attic completed with a clearance of at least 7 feet. Excluding non-liveable spaces: Garage, unfinished basement, and areas where you need to leave the main house are not included in the home area. However, the completed basement may be individually noticed on the list. Measure each floor individually: For multi-story homes, measure each level of livable space and add it together to determine the total area.
Although ANSI guidelines are widely used, local real estate markets may have different rules. Always check local regulations to ensure accurate measurements, especially when listing or evaluating your home.
4 easy steps to measure your home area
Step 1: Collect the tools
To measure the size of your home, you need to:
Measuring tape or laser distance measuring device pencil and paper (or digital note taking app) calculator
Laser measurers are particularly useful for large spaces and provide more accurate measurements.
Step 2: Divide the house into measurable sections
Instead of trying to measure the entire house at once, divide it into small rectangular sections such as individual rooms, hallways, and closets. This method minimizes errors and makes calculations easier. For non-rectangular rooms (such as an L-shaped area), divide them into smaller rectangles and measure them individually.
Step 3: Measure each room dimensions
For each room or section, follow these steps:
Measure the length and width in feet. Multiply the length by the width to get the area of that section.
For example, for a bedroom with a length of 12 feet and a width of 10 feet, the calculation is:
12 x 10 = 120 square feet
Then repeat this for every section of the house.
Step 4: Total area
Once each section has been measured, add all the values together to get the total area of the house.
Example of calculating the total square feet of a house:
room
Measurement (ft)
Square feet
living room
15×20
300
kitchen
10×15
150
Bedroom 1
12×10
120
Bedroom 2
12×12
144
Bathroom
8×6
48
Hallways and closets
n/a
100
Total area
–
862 square feet
What is important to the size of your home?
The area usually includes the completed, livable space within the home. Here are the things that are usually counted in official measurements and not counted:
Included in the home area:
✅ Finished bedroom, living room, kitchen and bathroom
heated heating and cooling areas (eg, central HVAC or permanent heating source)
✅The basement has been completed (if it meets the livable space standards)
✅A sealed sunroom (if heated and finished)
Not included in the home area:
Is the garage included in the area? No, the garage will not count in area as the habitable space is not complete.
Even if it is closed, an unfinished basement
❌Attic or loft that does not meet height requirements (usually at least 7 feet tall)
❌Pouch, deck, patio (unless it’s surrounded and heated)
Please check the local guidelines
If you are selling a home, check your local real estate guidelines as the definition of “livable area” may differ.
For example, a Los Angeles home has certain rules for measuring a livable space, especially when it comes to balconies, garages, or basements. NYC has strict building codes that distinguish between “liveable” and “non-resident” spaces. This means that if a particular room or area does not meet certain criteria (such as windows and ceiling heights), it may not count towards the total area. Also, in Seattle, rules regarding livable areas may be affected by zoning laws and building permits, and certain areas such as lofts and small rooms on the second floor are different to standard living spaces. will be counted in.
How to measure irregularly shaped houses and spaces
If your home isn’t a simple rectangular shape, don’t worry. You can also measure the area of your home, but you may need to use a few different methods.
L-shaped areas: divide them into two rectangles, measure them individually, and add area.
Triangular space: Measure the base and height and use the equation.
(Base x Height)/2
Circular area (such as a turret or a round room): Measure the diameter (distance through the center of the circle) and divide the diameter into two to obtain the radius. Next, use the formula:
π×R2
How to measure a multi-storey home
Each level must be measured separately and added together. The total area includes all completed areas on all floors, but excludes unfinished attics and basements.
How to measure an open floor plan
For open concept spaces without clear room departments:
Measure the total length and width of the open area. Subtract areas not included in the livable space (e.g., stairwells, unheated solariums).
Why accurate area is important
Knowing how to properly measure a square image is:
Real Estate List: Buyers compare homes based on prices per square foot. Home Rating: Square footage affects property values. Renovation: Knowing the exact dimensions can help you with materials and budgeting. Property Tax: Local governments will assess your taxes based on the area of your home.
Area plays an important role in the value of a home, so both buyers and sellers need to ensure that the numbers are accurate. Even small inconsistencies can affect home prices, valuations, and buyer negotiations. The following are the considerations for each party:
For Sellers: Do not overstuff or understate the size of your home
Don’t check: Even if you have a builder floor plan, footage of the plaza that was built will differ from the original design due to changes made during construction. Always measure independently or hire a professional appraiser. Avoid price pitfalls: Listing homes with incorrect area can lead to incorrect pricing. Legal and ethical considerations: Misinforming area (unintentionally) can lead to legal disputes and buyer requests that lead to low-cost demands. Some states have disclosure laws that require sellers to provide accurate home measurements.
For buyers: do not rely solely on list numbers
Please check the measurements. Real estate listings often draw area from tax records, which are not updated or accurate. Seek for a recent rating or measure your home yourself. Know what’s included: Some lists include enclosed areas of total area, such as a completed basement, solarium or an enclosed patio. Check what’s counting, especially in states with different rules. Inconsistencies in the assessment can affect funding. If an appraiser measures a lower area than the listed one, it could affect mortgage approval and home valuation, leading to renegotiation.
