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Square Footage Calculator

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Calculate the square footage of rooms, properties, and areas from measurements in feet, inches or meters. Useful for flooring, landscaping, carpets, garden or construction projects.

Disclaimer: Whilst every effort has been made in building our calculator tools, we are not to be held liable for any damages or monetary losses arising out of or in connection with their use. Full disclaimer.

Our calculator helps you estimate the area and material requirements for rooms, roofs, flooring, carpets, walls, pools, lawns, heat pumps and more. Continue scrolling down for instructions on how to manually calculate square footage, with formulas and example calculations.

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How to calculate square footage

If you're looking to install new carpet or flooring in a room, or work out what materials you require for a garden or construction project, you'll need to know how big the area is. This will help you accurately assess the amount of flooring, carpet or materials required for the project.

Follow these two simple steps to calculate square footage:

1 Measure your room or space

To calculate the square feet of a rectangular area, you first need to measure two dimensions: the length and the width (note that we discuss irregular shaped areas further down). Here's how to do this:

  • First, measure the longest side to find the length. Take a tape measure and fix one end of it to one end of the longest side. Note the measurement.
  • Next, measure the width - the shortest side of the area to be calculated. Repeat the process above and note down that measurement.

2 Use the square footage formula

For step 2, you're going to use the square footage formula:

Square footage = Length (feet) × Width (feet)

Note that the same formula applies if you measure in metric. In this case, the area will be expressed in square meters.

Insert your measurements into the formula. You're going to multiply the length measurement (in feet) by the width measurement. This gives you the area of the space in square feet.

You can also use this formula to calculate smaller areas when the area will be expressed in square inches and larger areas in square yards.

To give an example, if a bedroom measures 16 feet by 12 feet, the calculation would be 16 multiplied by 12, resulting in a square footage of 192 (16 × 12 = 192).

Calculating square footage for a rectanglar room

Calculations for 'L' shaped rooms or areas

Sometimes, you might need to calculate a space that's an addition to the main area or a room that isn't evenly shaped. In these situations, think of the space as separate areas. You may find it helpful to sketch out a quick floor plan to divide the space into more regular shapes.

  1. Measure the length and width of each separate area and calculate the area of each in square feet.
  2. Add your calculations to give you the total area in square feet.

Example calculation

Calculating square footage for an 'L' shaped room

Suppose you have a rectangular living room with a narrower dining area attached. Think of the space as being made up of a larger rectangle and a smaller rectangle.

First measure the length and width of the larger section labeled A, then do the same for the smaller section labelled B.

A: 14ft × 10 ft = 140 sq. ft
B: 6 ft × 5 ft = 30 sq. ft.

Now, add both values to calculate the square footage of the room:

140 sq.ft. + 30 sq.ft = 170 sq. ft

So you'll need 170 sq. ft. of flooring materials for this room.

Adding 10% surplus for materials

Once you've calculated the square footage of the area, and know how much material you need to order for your project, adjust it to allow for waste. It's best to order 10% more than you think you'll need rather than the exact square footage.

How to add 10% surplus to allow for waste

Mistakes can happen, and if you only have the exact amount you need, you might not be able to source matching materials. If you find that you don't need the extra materials, suppliers are usually happy to refund unused tins of paint or unopened packs of tiles. And if you have space, it can be handy to store the surplus materials for any touch-up repairs that are needed in the future.

Once you have your square footage figure, you can work out what materials you might need. We have an article covering how to measure for flooring or carpet for a room or house, if you need it.

How to calculate square footage for walls

To calculate the square footage of a wall, you'll need to:

  1. Measure the height of the wall from floor to ceiling (don't include baseboards and moldings).
  2. Measure the length of the wall, including any doors and windows.
  3. Multiply the height by the length to get your total square footage.
  4. For better accuracy, measure and subtract areas like windows, doors, and closets that won't be covered.

By following this process, you'll have an estimate to help you calculate the amount of materials needed to paint or wallpaper your wall.

How to calculate the square footage of a house

Knowing your house's square footage helps with assessing property value, planning home improvements, evaluating insurance coverage, and sizing HVAC systems like heat pumps. Let's look at how to measure your home accurately.

If your house is a perfect rectangle then you can roughly calculate the square footage by measuring the width and length of the house and multiplying the two figures together. This will give you the square footage of each floor. If your house has multiple levels, calculate the square footage for each level separately, and then add them together to obtain the total square footage of the entire house.

Of course, it may be that your house isn't a perfect rectangle. Or, you may wish to only calculate the total square footage of the living space in the house. In this case, you can try the following process:

  1. Create a floor plan: Draw out a floor plan of each level of your house.
  2. Measure individual rooms: Measure the length and width of each room within the house. Make sure to measure from wall to wall, excluding any non-living spaces like closets. Use a laser measure or steel tape for best accuracy - cloth measuring tapes can stretch and give incorrect readings.
  3. Multiply length by width: For each room, multiply the measured length by the width. This will give you the area of each room in square feet.
  4. Add up the room areas: Add together the square feet measurements of all the individual rooms to get the total square footage of living space in the house.

For living space calculations, consider including and excluding the following from your calculations: 2

  • Include: Common areas such as hallways, staircases, closets, and foyers.
  • Exclude: Non-living spaces like garages, unfinished basements, and utility rooms, as they are not typically considered part of the living space.

Edina Realty has a good article on what to include/exclude, if you want some more clarification.

Here's a video example of how to draw out a floor plan to calculate the square footage of a house...

It's important to note that this is a general approach for calculating square footage, and there may be specific considerations or variations based on local building standards or regulations. If you want an accurate measurement, it's worth seeking professional assistance from an appraiser or architect.

For real estate transactions, property tax assessments, or insurance claims, you may wish to consider hiring a professional appraiser for certified measurements that meet industry standards.

Once you know your property's square footage, our price per square foot calculator can help you evaluate what you're paying per square foot, whether you're buying, selling or renting a property.

Interesting fact

The average size of a single family house in the United States is 2,407 square feet, according to Statistica. House sizes have doubled since 1975 as living preferences have evolved. 1

Other shaped areas

It may be that the area you're looking to calculate is a triangle or circular shape. So, let's quickly cover how to calculate square footage for these shapes:

Square footage of a triangle shape

Here's how to calculate the area of a triangular-shaped area:

  1. Measure the base and the height of the triangle in feet.
  2. Multiply your length and width measurements together.
  3. Divide your total by two to get the square footage of the triangle
How to measure and calculate square footage for a triangle shape

Square footage of a circle shape

Here's how to calculate the area of a circular-shaped area:

  1. Measure the diameter of your circle in feet.
  2. Divide your diameter by 2 and then square it (multiply it by itself).
  3. Multiply your total by π (3.14159265)
How to calculate square footage for a circle shape

If you're calculating a square feet measurement for a garden or construction project, it's worth considering our volume tools, such as our cubic yards calculator for bulk materials like mulch or gravel, and our CBM calculator for shipping.

Summary of calculations

Here's a summary of what we've covered:

Sq. ft Calculation (in feet)
Rectanglar room/area Width × Length
L-shaped room/area Split the area or room into separate rectangles and measure each separately
Wall Height × Length (then subtract windows, doors and closets)
Triangular room/area Length of base × Height / 2
Circular room/area π × [Diameter / 2]²

If you want to work out a cubic feet volume based upon your square feet figure, you can try our square feet to cubic feet calculator.

And, if you're measuring land, we have a handy tool to help you convert between acres and square feet.

Calculator by Alastair Hazell

References

  1. Statistica. Median size of single family housing unit in the US from 2000 to 2020.
  2. Edina Realty, Inc. What’s included in square footage of a house?.