Whether you are calculating the square footage of a piece of land, your house, or a room, the steps are similar.
Step 1: Calculate square footage for a lot Calculate the square footage of your piece of land by multiplying the width of the lot by its depth. For example, if your land is 55 feet wide and 100 feet deep, your lot's square footage is 6,050 square feet.
TIP: If your lot has an odd shape, break it up into rectangles and squares. Calculate the square footage of each section, and add the results.
Step 2: Calculate acreage Start with acreage as an alternative to feet. If you know your lot size in acres, multiply the total acreage by 43,560 to get square footage. There are 43,560 square feet in one acre.
Step 3: Calculate for a home Calculate the square footage of your home from the outside by measuring the total area taken up by all enclosed spaces that are used year around. Exclude unfinished spaces, spaces that are not heated like the main body of the house, and the garage.
Step 4: Calculate for a room Measure the length and width of any room whose square footage you wish to determine. If the room is rectangular just multiply the measured length and breadth to get the square footage. Otherwise break the room into geometrical sections and do the calculations from there. Then you will have the square footage.
FACT: Throughout history, almost every culture has used the human foot as a unit of measurement. The ancient Greek foot was about 12.1 inches and the ancient Roman foot was about 11.7 inches.