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How to calculate square feet
To calculate an area in square feet, you will need measurements for the width and length (for a square shape) or the diameter (for a circular area). It may be that the area you're looking to measure is a strange shape (such as a room or garden). In this case, dividing it up into smaller parts and doing individual calculations is a good way to calculate the overall square footage.
Let's say you have a rectangularshaped room and you want to calculate the square footage area for flooring or carpet. The easiest method for calculating the square footage is to measure the length and width in feet and then multiply the two figures together to give you a result in ft^{2}. If you're measuring a room for flooring, take a look at our article on how to measure for a new floor.
Should you find yourself needing to calculate an area of square feet in an 'L' shape, consider dividing the shape up into rectangular sections and treating them as separate areas for calculation (adding them together at the end). For more instructions, see our full article: how to calculate square footage.
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How to calculate square footage?
It’s easy. Follow these steps.
Measure the length in feet, Measure the width in feet. Multiply the length figure by the width figure. This will be your total square footage for that portion of your project. Continue to repeat this for all parts of the space that will get the same tile. Add these together for your total square footage.
Measuring in inches works as well. Do the math the same way, then divide by 144 to get your total in square feet. When calculating square footage account for the entire space (i.e. under vanity/cabinets).
How many square feet is a 20×20 room?
The square footage of a room measuring 20 feet wide by 20 feet long is 400 square feet. To calculate this you simply multiply the width by the height. 20ft × 20ft = 400 sq ft.
How to calculate how many pieces of bullnose you will need?
If you have ten feet exposed edge that needs bullnose this is equal to 120″. If you selected a 6″ bullnose or trim piece, you will need to divide 120″ by 6″, which will give you 20 pieces of bullnose needed. Using 8″ decorative liner for the same 120″, you divide 120″ by 8″ which would be 15 pieces of liner needed.
How to figure square footage of a wall?
It doesn’t matter whether you’re thinking how to calculate wall square footage for paint or for wallpaper – it’s the same. Use these pieces of advise to improve your ability to figure out the square feet of your wall:
Precise measurement is the key 🔑 – no matter if you’re using the wall sq ft calculator or computing everything yourself:

Start with drawing a plan of your room/house – it’ll make it easier to measure and store data;

Alway use the proper equipment – a steel tape measure or a yardstick;

Measure the length of your walls, including both doors and windows; and

Determine the height of your walls – measure them from the floor to ceiling. Exclude the length of a dropped ceiling or moulding (coving).
It’s math time! Let’s find out how to calculate the square feet of a wall.
So how do we calculate the square feet of a wall? The equation is simple:
walls square footage = total length of the walls * ceiling height
But how to calculate sq ft of a wall with doors and windows? 🤔
corrected wall square footage = wall square footage  windows area * number of windows  door area * number of doors
Now it’s time to figure out the square feet of windows and doors – take a look at the standard sizes, presented in the table below:
Windows  3 x 4 ft  12 ft² 
Doors  3 x 7 ft  21 ft² 
That’s how to calculate square feet of a wall. Are you still at the beginning of your journey, not yet sure about the number of planned doors and windows? Try our basic construction calculators:
 Find out how to deal with wood & steel framing;
 Estimate the amount of drywall you’ll need;
 Dreaming big? Try the concrete block wall calculator or the brick calculator 🧱
On this page:
 Wallpaper Calculator
 How to Estimate How Much Wallpaper You Need
 Step One: Find the Square Footage of the Room
 Step Two: Find the Wallpaper Coverage
 Step Three: Calculate Wallpaper Rolls Needed
Window and Door Concerns
Since all rooms have at least one door and most have windows, feel free to subtract the square footage of these elements from your wall calculations. Either measure the square footage of each window and door individually, or estimate these numbers. The typical door is 21 square feet, while the average window is 15 square feet. Subtract the total square footage of windows and doors from the wall square footage to determine the total square footage of wall space requiring paint.
The typical online paint calculator square feet measurements include estimates, not exact measurements, of window and door sizes, as well.
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