How to Estimate Topsoil

Rectangular Shaped Projects

• 1). Draw a diagram on your paper of the general shape of your project. This will be your guide to keep track of your measurements.
  
  
• 2). Use a measuring tape to measure the length of your project in feet, and record it on your diagram.
  
  
• 3). Measure the width of your project in feet, and record it on your diagram.
  
  
• 4). Decide how many inches deep you need the topsoil, and note this next to your diagram for the final calculations.
  
  
• 5). Take the measurements from your paper and multiply the length times the width times the depth you have decided on. Divide that number by 324 to get the number of cubic yards you will need for your project.
  
  

Circular Shaped Projects

• 1). Take a piece of string and tie it to a straight stick or pole, and place the stick into the ground on one edge of your circular garden. Run the string across the circle, tie it to another stick, and place it in the ground on the other side.
  
  
• 2). Take a second piece of string, tie it to a straight stick or pole, and place it in the ground 45 degrees apart from the other sticks. Run the string across the circle once more, and place the stick into the ground. You will create four quarters.
  
  
• 3). Measure in feet the radius of the circle or the distance from the center point to the side of the circle. Write down the measurement on your paper.
  
  
• 4). Determine the depth of soil, in inches, that you want for your project, and write it down on your piece of paper.
  
  
• 5). Use the following formula to calculate the cubic yards required for your project: 3.1416 (Pi) x radius (feet) x radius (feet) x depth (inches) divided by 324.
  
  

Triangular Shaped Project

• 1). Measure with your measuring tape the base of the triangle-shaped garden in feet, and write it down on your piece of paper.
  
  
• 2). Measure the height of the triangle in feet, and write that measurement down on your piece of paper.
  
  
• 3). Determine the depth of topsoil that you will need in inches, and write that down.
  
  
• 4). Multiply the base of the triangle (feet) by the height of the triangle (feet) and divide by 2.
  
  
• 5). Multiple that number by depth (inches) and divide that by 324 to calculate how many cubic yards of topsoil you'll need.