How to Determine Square Footage 

Introduction
Determining square footage is easy, it has a lot to do with math and all you need to know is a couple of useful formulas that you probably remember from school. If you don’t – just use our article. Here we will tell you how to calculate square footage if your space if square, rectangular, or even round. There is nothing easier, you just have to follow guidelines that we provide.
Do's
You will need:
 a math formula;
 measuring tape;
 a sheet of paper;
 pencil;
 calculator.
Guidelines:
Take measurements
Measure each side of your space. If it is a room, measure length of the walls by driving measuring tape along the floor from corner to corner. You may need a helper for that. Write down all the numbers. If your room is round, measure its diameter: drag measuring tape through the room (in the middle) and write down the number that you get. If there is more than one room, take measurements in all of them and combine their footage after you calculate it.
Pick a formula and determine square footage
After you take all the numbers, figure out what shape your space is. If it’s round, us the following formula:
Circle A = ?r^{2}.
Where ? is 3.14 and r is half the diameter (the number you got after measuring). If diameter is 20 ft, then radius is only 10: A = 3.14 x 10^{2} = 3.14 x 100 = 314 ft^{2}. If your space is a square, use this one:
Square A = b^{2}.
Where b is the side, for instance – all the sides are 12 ft which means your space is square and you have to use this formula: A = b^{2}= 12^{2}=144 ft^{2}.
Although perfectly square spaces are very rare, and you probably have a rectangular one. In this case you are going to need the following formula:
Rectangle A = b x c
Where b is one of the long sides and c – one of the short ones (it doesn't matter what letters you use to identify them). If your space is 20x10 ft, simply multiply those numbers: A = b x c = 20 x 10 = 300 ft^{2}.
If space is of an irregular shape
If your space is like the one in the picture, you simply have to take more measurements. Try to see space as a set of geometrical figures, take measurements, use formulas to calculate footage for each part of the space and add up the results.
Rectangle #1: 8 and 4; rectangle #2: 3 and 2: A = 8x4 + 3x2 = 38 ft.
Don'ts
 Don't forget to make sure you calculated everything right, always use a calculator.
 Don't forget to convert feet to inches or inches to feet if your numbers aren't whole.
Video
Conclusion
As you see, calculating square footage is the same thing as finding the area of a geometrical figure. If you have a measuring tape and the right formula, determining square footage won't take much time. Double check your results to make sure they are correct.
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