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measuring the square footage of a room image

How to Calculate The Square Footage of a Room

When buying new flooring for your home you will have to calculate the square footage of the rooms where your new flooring will be installed. You will then know the exact amount (in square feet) of laminate, vinyl, carpet, or whatever flooring you have chosen you will need to buy.

Every single area that your flooring is to be installed must be included in your calculation. Once you have all these areas accounted for you can add all your measurements together for the total square footage of flooring that you will require.

One accurate measurement is worth a thousand expert opinions – Grace Hopper
Knowing the square footage will allow you to order your flooring with confidence, and avoid ordering too much, or not enough to finish your flooring project.

You will also be able to accurately estimate the total cost of the flooring and how much it will cost to be installed (if you do not plan to do this yourself).

Remember that you will need to order approximately 5% more than your final calculation to account for wastage (we will cover this in more detail later in the article).

I love the quote “One accurate measurement is worth a thousand expert opinions”. Measure each room two or three times to ensure all your measurements are correct.

To measure your room you will need:

  • Tape measure
  • Pencil
  • Notepad
  • A friend or family member*
 *A friend or family member’s help to take the measurements will ensure they are as precise as possible. 

 

How to Calculate the Square Footage of a Room:

Rooms come in all shapes and sizes; most are perfectly square, or rectangular-shaped, but many also have additional areas such as closets or bay windows that will also need to be considered.

Most rooms are commonly made up of one or many rectangular-shaped areas that come together to form the overall space of the room. To ensure accuracy we will measure each of these areas separately, then add them to our total figure.

First, let’s look at how to measure a basic room layout.

How to measure and calculate the square footage of a square or rectangular room:

The easiest room to measure is one that is rectangular shaped. This is because there are no additional areas to account for.

The diagram below (i) illustrates a rectangularly shaped room.

Diagram (i)

Square Feet Measuring Diagram

The room is 14ft long by 10ft wide, so to find the area of the room in square feet we would multiply the length by the width.

The equation:
Square Footage = Length (ft) x Width (ft)

So to find the square footage of our room we would multiply 14 ft x 10ft.

Our Example: 14 ft. x 10 ft. = 140 ft² (or 140 sq. ft.)

This room has an area of 140 ft² (or 140 sq.ft).

How to Deal with Inches

In the real world, it is unlikely that your room will be exactly fourteen feet long by ten feet wide. In fact, more likely than not you will have to deal with inches. See diagram (ii) below.

Why We Don’t Want to Round-Up (or down) to the closest foot.

It is important that we don’t just blindly round up our figures to the nearest foot. This can mean we buy too much flooring, and our costs increase exponentially.

For instance, if our room was 14 ft. 1in. In length and the width was 10ft. 1in and we round up to 15ft. and 11ft. respectively you could easily be excused for believing that this would only be an extra square foot (or just under) of flooring (as 1 x 1 = 1), however, this is not the case.

Let’s look at an example:

Rounded Up: 15 ft. x 11 ft. = 165 ft. sq.
Exact: 14ft 1 in. X 10 ft. 1 in. = 142.01 ft. sq.

In this example, you would have purchased almost 23 square feet too much flooring.

And now let’s look at the example in the diagram (ii)

Diagram (ii)

Measuring Square Feet with Inches Diagram

Rounded Up: 15 ft. x 11 ft. = 165 ft. sq.
Exact: 14ft 9 in. X 10 ft. 4 in. = 152.42 ft. sq.

In this example, we would have purchased 13 square feet too much flooring.

Of course, rounding down wouldn’t provide us with enough flooring to get the job done, so that is also not an option.

So let’s look at how we deal with this.

Three ways to calculate square footage using feet and inches.

There are three ways to make this calculation; mathematically, using an online calculator, or estimating it using a conversion table.

The first two options will provide you with an exact answer. The conversion table method will provide you with a very close estimate – which is perfectly OK for this type of calculation.

Mathematical Calculation

The mathematical calculation is relatively straightforward. Though the division of 144 may even confuse those with an educational history in mathematics. For the sake of this article, and so we don’t vere into a math lesson we will just calculate diagram(ii) using the formula.

14 ft. x 12 + 9 = 177

10 ft. x 12 + 4 = 124

177 x 124 = 21948

21948 / 144 (always this number) = 152.42

Online Calculator

By far the easiest method is using an online calculator to help you calculate the exact square footage. I suggest this one at the calculator site, which allows you to input both feet and inches for exact square footage.

Square Footage Calculator Image

Table Calculation (rough estimate)

Using the table below to calculate the square footage of flooring you will need will always work out either exactly correct or overestimate by a little.

INCHES DECIMAL INPUT NUMBER
0.25 – 3 0.25 FT. + 0.25
3.25 – 6 0.50 FT. + 0.50
6.25 – 9 0.75 FT. + 0.75
9.25 – 11.75 1.00 FT. + 1.00

You simply measure the length and width of the room in feet and inches, run both these numbers through the table above then multiply them to give you the approximate square footage that you will require.

While the figure is estimated it will still ensure you do not over-order expensive flooring to the degree that we previously discussed.

So for the example in diagram (ii)

14ft. 9in. = 14.75

10ft. 4 in. = 10.50

14.75 x 10.50 = 154.88

How to measure and calculate the square footage of a square or rectangular room with additional areas, such as closets:

Not all rooms are perfectly square or rectangular shaped. Therefore it is likely you will need to measure your room while taking these areas into account.

Below I have created a diagram that I believe illustrates the sort of difficulty you may face when measuring a “real world” room for flooring.

You are best to separate all the areas required to be measured into squares and rectangles and measure each area separately. Convert each area’s measurement into square feet, then simply add everything together.

Diagram (iii)

Measuring a Room With Closets Diagram

In diagram (iii) we have the main living area, that we have already calculated, with two additional closets.

For the purpose of illustration, the two closets are identical in size, however, in the real world, they are likely to have been built to different specifications.

To calculate the total square footage of this room we would:
1. Calculate the main living area (152.42 ft. sq.)

2. Calculate the area of each closet (both are 19.51 ft. sq.)

3. Add all the areas together.

So our total square footage would be:

152.42 + 19.51 + 19.51 = 191.44 ft. sq.

Accounting for Wastage (Important)

Before we order our flooring it is important to account for wastage. Not every plank of wood or laminate will be able to be used in its entirety.

There will be offcuts, errors, damaged or off-colored planks that you would prefer not to use. Wastage is an important factor to consider when ordering any flooring.

Many websites online suggest 5%, however, through my own experience I am a lot more comfortable with a 10% figure. This is especially true if you are planning to lay the floor yourself.

If you have too much flooring, such as a spare box, this can prove valuable in the future when you want to replace a plank or two, or perform some minor fixes. Flooring too often becomes obsolete, so finding the same flooring in years to come may be nigh on impossible.

Also, the thought of also being a single box short to finish a job brings me out in hives, but it is a personal choice.

Calculating Wastage

To calculate the total square footage when adding wastage is a simple calculation.

Our total from our example above was 191.44 ft. sq.

To calculate our new total (when accounting for wastage) we would simply multiply this amount by 1.1.

So, 191.44 x 1.1 = 210.58 ft. sq.

If you were wanting a 5% wastage you would multiply by 1.05.

If you have followed this article and implemented all the techniques when measuring your room or rooms for flooring you should easily have managed to calculate the exact square footage of your room and how much flooring you will require.

Simply divide the box coverage by this total amount and you will have no problem ordering the correct amount of flooring for your new floor.

Happy DIYing!