Things You'll Need
If you're planning to lay hardwood flooring or tile, you need to know how to calculate the square footage of the room(s) in your home. Rooms in most homes are either square or rectangular. If your home has rooms that are irregularly shaped, you need to demarcate areas in the room into squares, rectangles, triangles or circles when measuring them and then add the results of all your calculations so you can determine how much material you need to buy for your flooring area. Don't forget the closet areas.
Square Footage of Squares and Rectangles
Measure the length and width of the floor in your room. Round your measurements up to the nearest foot. For example, if the length of the room from baseboard to baseboard is 20 feet 2 inches, round it up to 21 feet. If the width of the room is 16 feet, 7 inches, round it up to 17 feet.
Multiply the length by the width to get the square footage of the room. So 21 x 17 = 357 square feet.
Add the rounded square foot measurements of each square or rectangular shape in the room(s) and closet(s). This square feet number will help when you go to a store to buy your materials.
Square Footage of Triangles
Measure the base of the triangle and round up to the nearest foot. Measure the height of the triangle from the base to the point of the triangle. Round up to the nearest foot. the long line attached to the right angle
Multiply the base of the triangle by 0.5. If the base is 6 feet, then 6 x 0.5 = 3.
Multiply the result of the calculation in Step 2 by the height of the triangle. For example, if the height is 8 feet, then 3 x 8 = 24 square feet.
Square Footage of a Circle
Measure the diameter of the circle and round up to the nearest foot. The diameter is the distance across the circle.
Divide the diameter by two to get the radius of the circle. The radius is the distance from the center of the circle to the outside edge. For example, if the diameter is 10 feet, the radius is 10/2 = 5 feet.
Square the radius. For example, if 5 feet is the radius, the radius squared is 5 x 5 = 25 feet.
Multiply 3.14 (pi) by the square of the radius to get the square footage of any circle.
You don't need precise square footage measurements. It's always better to overestimate square footage than to underestimate it when installing flooring material.