Sketch a rough drawing of the piece of land.
Measure the perimeter of the land with a tape measure. Measure the land in feet and inches. You may want to get another person to help you by holding one end of the tape measure as you read the other end. Record your measurements on your sketch.
Convert your measurements to inches by multiplying feet times twelve and adding any extra inches on to your answer. For example, if one side of the plot of land is 50 feet, 5 inches, you would multiply 12 times 50 to get 600. Then you would add the 5 inches to get a total of 605 inches for that particular side.
Find the area of the piece of land by using its measurements in formulas that are designed according to the shape of the plot. If the land is in the shape of a rectangle or square, you simply multiply the length times the width to find the area. If the plot is shaped irregularly, divide the drawing into rectangles, squares, triangles and circles, as dictated by the shape of the land. To find the area of a triangle, multiply the base times the height and divide by the number 2. To find the area of a circular piece of land, multiply the radius squared times pi (3.14). The radius is half of the diameter (width) of the circle. Squaring the radius means to multiply the radius times itself.
Divide your area in inches by 144 to find the number of square feet.