How To Calculate Square Feet Of A House

How To Calculate Square Feet Of A House

November 10, 2022

A short overview

Do you know how many square feet your home is? Knowing how to measure square footage of an investment property is a valuable skill for real estate investors. From property taxes to renovations, calculating the square feet of a home is an important tool that is used for many purposes, here’s how to do it.

house for sale

Knowing how to calculate square footage of a house is a useful skill for real estate investors, particularly those who are doing fix and flip projects. The ability to calculate the square feet of a house means that investors can easily calculate the price of the house, by working out the rental or purchase price per square foot.

This calculation also means that investors can quickly estimate the renovation costs for projects such as replacing the flooring, or painting. Keep reading to find out how to calculate square feet of a house.

How to calculate square feet of a house

First things first, let’s make sure we’re clear on the meaning of a home’s square footage. This is the total amount of flat space that covers a particular area. Surprisingly, there is no national standard used to calculate square footage of homes. As such, it’s easy to get this calculation wrong, and it’s important to know how to do it correctly. Let’s take a step-by-step look at measuring how many square feet a home is.

square footage of house

Step 1: Measure the areas of the house

To start, you’ll need to get a paper and pen (or something to note down measurements), a measuring tool such as a measuring tape or laser measuring tool, and a calculator. It’s also a good idea to sketch out the house so that you can note each room that needs to be measured.

Then you’ll need to go to each area of the home and measure it. For rooms that are rectangular you will measure the length and the width. Other areas, such as alcoves, will also need to be factored into the measurements as well. Once you’ve calculated the area of each room, you can add these to your sketch to make sure that each room has been calculated.

Step 2: Convert all measurements to feet

Make sure that all the measurements you have done are converted into feet. If you’ve measured in inches or yards, you can do a quick calculation to convert them into feet. When you are done, it’s time to go ahead and begin calculating the home’s square footage.

Step 3: Use the formula to calculate square feet

Area In Square Feet = Length (in feet) x Width (in feet).

For rectangular areas, the calculation is simply the length of the room multiplied by the width. For more complicated areas, you’ll need to measure the areas outside of the rectangle and add those to the overall square footage of the room. Calculate the square feet of each room and make a note of it.

For example, if a room is 30 feet wide by 11 feet long, then 30 x 11 = 260 square feet.

calculating square footage

Step 4: Add it all together

Your final step in the process is to add together the area of each room, to calculate square footage for the house.

An example of how to work out a home’s total square footage:

Kitchen: 400 ft
Bedroom 1: 200 ft
Bedroom 2: 150 ft
Bathroom: 50 ft
Hallway: 20 ft
Living room: 100 ft

Total square feet = 920 square foot

How to measure square footage of an odd shaped room

While measuring rectangles may seem simple now and the idea of measuring other rooms more confusing, it’s easier to think about it as a lot of small boxes.

calculating square footage

Square & rectangular areas

Square and rectangular areas are the easiest to measure because they follow the basic formula, which is length (in feet) x width (in feet) = total square feet. These rooms have a shape that lends itself to the simple formula, without the need to factor in any extra areas.

L-shaped areas

Divide L-shaped areas into a square and a rectangle and measure the length and width of each of these. Multiply them together, to calculate square footage of each section. Once you have these 2 numbers, you can add them together to figure out the total square footage for the room.

For example

Square area: 30 ft x 25 ft = 750 sq. ft.

Rectangle area: 12 ft x 20 ft = 240 sq. ft

Total: 750 + 240 = 990 square foot

Triangular areas

The formula for calculating the square feet of triangles is:

A = 1/2 base x height

In this case, ‘A’ is the area of the triangle in square feet, ½ base refers to the length of the bottom side of the triangle in feet and the height is distance from the bottom side of the triangle to the top, vertically. Bear this in mind when you’re looking at how many square feet a triangular area is.

  • Step 1: Measure from the base of the triangle to the top, in square feet. This will be the height.
  • Step 2: Measure the base of the triangle, which is the length of the bottom side, ie: along the floor on the longest side.
  • Step 3: Divide the length of the base by 2. This will halve the number.
  • Step 4: Multiply the height by half the base and this will result in the total square footage of the triangular area.

Circular Areas

The formula for calculating square footage of a circle is:

A = π x radius2


  • Step 1: To calculate square footage of a circular room, first work out the radius. To do this you can find the middle point of the circle (room) and measure between this point and the edge.
  • Step 2: Multiply the radius by itself, to work out the radius squared.
  • Step 3: Multiply the radius squared by pi (3.14), to end up with the total square feet of the circular area.

What is livable square footage?


Liveable square footage is, as the phrase implies, anywhere within a home that is habitable. This includes the likes of bedrooms, bathrooms, kitchens, living rooms and dining areas. Areas like the yard, exterior hallways and stairwells would not classify as livable areas.

There are rules and regulations relating to livable space, so it’s worth checking these out for your area, to get a more accurate idea of what is and isn’t considered livable. For example, in some cities, cellars are not considered livable square footage unless the floor-to-ceiling height is over 50% above grade.

Floor area vs lot area - What's the difference

While the floor area and the lot area may sound similar, the two have some key differences. When looking at the square foot areas of the house to calculate, this difference is important to know.

Floor Area

The floor area is the area inside the house that can be occupied. Which includes any occupiable area up to the exterior walls and including the exterior walls themselves. Floor areas will cover bedrooms, bathrooms, and kitchens that are located inside the building.

Lot Area

The lot area is the total area of the property, it includes the yard up until the point of the boundary lines. The lot includes the building (house) and other areas which are not built on but form part of the plot of land. This includes walkways, balconies and decks.

The main difference between the floor area and lot area is therefore the areas that are covered. With one being areas that are occupiable, and the other being all areas within the lot itself, regardless of whether they are occupiable or not.

Final tips on measuring square footage correctly

Now that you’ve got a good grasp on how to measure the square feet of a house, you can use it for a variety of purposes. A home’s square footage comes in useful, not only for lending purposes, but also for renovating and reselling. For rent and purchase prices, the price per square foot is vital to know. As such, for real estate investors, learning how to calculate square footage of a house is a valuable skill.

For homeowners, a home’s square footage can come in handy when they’re doing upgrades, buying new furniture or anything else that might entail the dimensions of the house. Knowing how many square feet a house is, is important for property taxes too, as this can help with getting taxes reduced if they have been assessed at a higher amount than they should be.  

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