How to Measure the Square Footage of Your House

Know exactly how big your house is, and maximize the way you use it.

U.S. News & World Report

Measuring Your Home's Square Footage

It can be a big help to know your home's square footage – and how to measure it.(Getty Images)

When you’re simply going through your normal day-to-day activities, the exact size of your home may not seem so important. But when it comes time to sell your home, make a renovation or even buy a new piece of furniture, knowing the precise square footage is a key step in the process.

Your first impulse may be to rely on the documented dimensions, but when the Zillow profile for your house, your local assessor’s office and old blueprints for the property all seem to give slightly different dimensions, it’s best to take on the job of measuring the interior yourself.

For the simplest way to measure the square footage of the rooms in your house, you’ll need:

  • Tape measure
  • Paper and pencil
  • Calculator

(U.S. News)

How to Measure Square Footage of Your Home

You might remember from your middle school math class that the easiest method for measuring square footage is to start with a square or rectangle. If you’re lucky, most of the rooms in your house are simple boxes. Calculate the square footage by multiplying the length of the room by the width in feet.

If you have an oddly shaped room, you can make the process easier by breaking a room down into smaller rectangles. Measure a nook separately from the rest of the room, for example. If the nook is shaped like a triangle or the room is shaped more like a trapezoid, measure the rectangle first, then calculate the area of the triangular space after.

To measure the triangular part of the room, multiply the base and height of a right triangle and divide by two. Note that you may need to measure the triangle in two parts if the triangle isn’t already at a right angle.

If all or part of the room is rounded, you’ll need to calculate the area by using the formula for the area of a circle, which is the square of the circle's radius (half its diameter) multiplied by pi. For partially circular rooms, divide the total circle area by the share of the circle in the room. For example, if one side of the room makes a half circle, divide the circle area by two.

Don’t forget to add the areas for the shapes together to calculate the square footage for the entire room. Repeat throughout your house to determine the livable square footage of the interior of the house – and remember to include hallways and closets.

Keep in mind that how you measure your home’s square footage and how another person may measure it can vary. For the sake of furnishing a room or purchasing a home, the interior square footage, or the space between all the walls, is likely the most helpful. When it comes to measuring for the sale of a home, you want to include all completely finished floor space. A finished basement or attic should have walls, a floor and ceiling, and any necessary egress or ceiling height to meet your local building code.

Many professionals in the building and construction industry may report the gross square footage of a home, or the total footprint of the structure on the property, which measures along exterior walls.

“Gross to net (square footage) gets reduced when you have thicker walls,” explains Dwayne MacEwen, principal at architectural and interior design firm DMAC Architecture, based in Chicago. Walls can be thicker due to the material used to build the structure or the chosen facade of the building, combined with necessary insulation. Houses in the Midwest are more likely to have thicker walls than houses in Southern California, for example, because additional insulation is necessary for the cold winter months.

How Does Your Home’s Square Footage Compare?

Once you've calculated your house's square footage, you may wonder how it stacks up against homes throughout the country. In 2017, the median size of a newly completed single-family home was 2,426 square feet, according to the U.S. Census Bureau. But new construction homes haven’t always been so big. In 1995, the Census Bureau reported the median size of a new single-family house in the U.S. was 1,920 square feet. Looking back to 1973, the first year the data became available, the median newly constructed single-family house in the U.S. was 1,525 square feet.

Total livable square footage plays into a home appraisal, when an appraiser will consider the total size, number of bedrooms and recent renovations to find similar, nearby properties that have recently sold and compare them to determine the market value of the property in question. However, more square footage doesn’t always guarantee higher value – it’s more important how the space is used.

For example, hallways or transitional areas between rooms are a part of the total square footage of a home, but when they’re not consciously designed, they can feel like dead space. The key to making that additional square footage feel like it contributes to the house “has to do with, honestly, how well it’s designed,” MacEwen says.

Keeping hallways wider, open to other rooms and including windows to allow natural light can keep that transitional area usable, MacEwen says.

Planning With Your Square Footage

Whether you’re looking to renovate rooms that will change their layout, construct an addition onto your home or build a custom home, paying attention to square footage plays a vital role in the planning process.

First and foremost, the property’s allowances for the size of a structure or how close it can be to the property line based on local law must be known. “(Regulation is) actually one of the biggest driving factors for us,” says Julie Fisher, partner at Chicago architecture firm fcSTUDIO Inc.

The architect and builder will want to reference a survey of the property and all details about its zoning before creating a plan for the house to avoid legal issues with the city or county. It’s possible to request an exception to zoning or building code, although the approval process can be lengthy and there’s no guarantee your request will be granted.

Aside from following the rules on how big of a footprint your house can have on your land, Fisher and MacEwen both stress that it’s important to be mindful of how you’ll use the space, rather than how big you can make a room or part of the house.

“People think the bigger the kitchen, the more grand the house is,” Fisher says. But if you just keep adding square footage to the kitchen, cooking a meal can feel like a workout when you’re running between the sink, refrigerator and stove.

Fisher says she focuses on keeping a short distance between the three appliances – also known as the kitchen work triangle – but then allowing the livable space connected to the kitchen to grow in size. That way, family and friends won’t feel cramped as they hang out in the kitchen, but the cooking process is still easy.

Imagine how you would use a room realistically, rather than how you think it should traditionally be used. Instead of a formal dining room that you may rarely use, for example, consider using that square footage as a living room that’s open to the kitchen, or close off the room for a private home office you wouldn’t otherwise have.

“What you think a house should be – those boundaries are being broken down,” MacEwen says.

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