Measuring Square Footage

Many complaints have been filed with real estate licensing commissions in recent years claiming that agents inaccurately reported square footage totals on multiple listing sheets, in ads, and within other advertising materials. Most square footage errors are not the result of an agent's desire to be untruthful; they occur because agents do not know how to take measurements and do the calculations. Become familiar with both tasks so that when you state a square footage total, you know it is accurate.

Some agents no longer advertise the square footage of their properties but your MLS might require you to include total square footage so that the house can be better categorized for searches. Square footage is important to most buyers too, and it can be passed on as an approximate number rather than exact total.

Your state real estate commission might have established guidelines to help its licensed agents measure and calculate square footage. If it hasn't, use the techniques in this chapter, which are based on standards that are widely accepted within the housing industry.


Agents who follow standard guidelines and document their measuring procedures and calculations are better equipped to defend their square footage findings if a homebuyer files a complaint after the sale. Keep all drawings and related materials in case you must show how a figure was obtained.

Only Count Finished Living areas

The square footage you report must be space that's intended for human occupancy and it must be heated by a conventional and permanent heating system. The area must have walls, floors, and ceilings constructed from materials that are generally regarded as acceptable for interior construction.


Never use square footage totals from a tax collector's office, a former MLS sheet describing the property, or from a seller. Do not even depend on blueprints, because changes are sometimes made to a home during construction. Unless your MLS guidelines allow otherwise, always measure the house yourself or hire a licensed appraiser to measure it for you.

One common square footage error involves finished rooms that are accessed through an unfinished area, such as a utility room that you enter by passing through a garage. Any room that is accessed through an unfinished area cannot be counted as finished square footage.

Measuring the House

You might be surprised to learn that houses are measured from the outside, although it's sometimes necessary to deduct space by measuring the dimensions of interior rooms, then adding space back in to account for wall depth. To get started, collect the tools you need to measure the house:

  • Paper and ruler (graph paper is handy)

  • A long measuring tape

  • Pencils and erasers

  • A calculator

Measure the length of one side of the house and round the figure to the nearest inch — or nearest quarter inch for better accuracy. Draw a line on your paper to represent the wall and record its length next to the line. Measure the remaining sides of the house, sketching in the shapes as you go and taking care to record lengths.

The simplest square footage to calculate is that of a square or rectangular house with no garage or other unfinished space. If the house is forty feet long by thirty feet deep, multiply those numbers together to get the total square footage, 1,200 feet.

Measuring Irregular Spaces

Mistakes sometimes happen when houses are more complex, with unfinished rooms that must be deducted from the total and with finished rooms that cannot be measured outside for some reason.

When you must measure an area from the inside, add four inches to the length of walls that butt against an interior wall and six inches to the length of walls that meet an exterior wall. The additions make the room dimensions more equivalent to its exterior measurement.

Rooms with Sloped Ceilings

Some attic rooms and rooms in chalet and A-frame houses have sloped walls. If you measure the dimensions of that type of room all the way to the point where the slope meets the floor you'll be measuring unusable space. Include only the portion of the room where ceiling height is at least five feet tall. Do not include the room at all if at least one half of its square footage does not have ceilings that are a minimum of seven feet high. (You may want to note the total floor area in the remarks section of the MLS, because this would be an important number when calculating certain things, such as the cost of new carpet.)

Bay Windows

The square footage occupied by a bay window may be counted if the area has a floor, a ceiling height of at least seven feet, and meets the other criteria necessary to qualify it as finished living space.

Furnace Room

The furnace, water heater, and other similar utility items are often located in a small room or closetlike area within the house. It may be included in the total square footage.

Hallways and Closets

Hallways and closets are included in the total square footage if they are a functional part of the living space.


If the upper opening for a stairway is larger than its area on the floor below, you should deduct the excess open space from the upper level's square footage.

Calculations for Specific Shapes

Most of your square footage calculations will be for squares and rectangles, but sometimes other shapes emerge as you sketch the house, such as circular areas for a bay window.

For squares and rectangles, multiply length times width to find the number of square feet. To calculate the area of a triangle, multiply the length of its base by its height and divide the result by two. Calculate the area of a circle by squaring its radius (multiplying it by itself) and multiplying the figure by 3.14. Determine the area of an octagon by first drawing lines to turn it into a rectangle and triangles, then calculating the square footage of those shapes individually.


Local laws dictate whether buyer's agents are responsible for verifying the accuracy of square footage. Most are not. If your buyers have doubts about the square footage estimates stated by the seller or listing agent, ask to see how figures were calculated. If your buyer wants to measure the house, offer guidance but allow the buyer to measure it herself.

Check Your Drawing

Take a close look at your drawing before you leave the house. Have you clearly marked all interior unfinished space? Should the drawing be more detailed? Are you missing important dimensions? Make the drawing as thorough as possible so that you won't have to return for another measuring session.

If measuring a house seems like too daunting a task, you may want to consider hiring an appraiser, architect, or other qualified professional to measure it for you. Find out what is acceptable in your area. There are times when it is impossible to measure from the outside — snow cover or the slope of the land may make it necessary to measure the property from the inside only. Find out the rules in your area and be sure to follow them exactly.

A successful listing presentation will result in a property for you to market and sell. If you are marketing a property, you have the chance of getting calls on that property, selling that property or another property, and the cycle of success can begin!

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