Consider calculating the total area of a trench to know how much land it covers. Knowing the the area required for a trench will tell you if it will fit in your yard and whether it's large enough for a given project. Trench applications include water drainage and spaces to place pipe or cables. The area of a trench depends on its physical dimensions. Common units of measure for trench area include square inches and square feet.

Measure the length of the trench in inches. For example, the length might be 345 inches.

Measure the width of the trench in inches. For example, the trench width might be 16 inches.

Multiply the length times the width to obtain the area of the trench in square inches. Performing this step leads to 345 inches times 16 inches, or an area of 5,520 square inches.

Divide the trench area by 144 to convert to square feet, because one square foot equals 144 square inches. Completing the exercise leads to 5,520 square inches divided by 144 square inches per square foot, or a trench area of 38.3 square feet.