Have a land survey conducted by a professional surveyor.
Look at the survey map and find the length and width of the land. This should be listed in units of feet.
Multiply the length and width measurements to calculate the land area in square feet. As an example, if your land measured 1,000 feet by 1,500 feet, the land area would be 1,500,000 square feet.
Divide the square footage by 43,560 to convert in into acres. In the example given in Step 3, 1,500,000 divided by 43,560 yields 34.44 acres.