Enter the area, desired depth, and rate of amendment into the calculator to determine the soil amendment needed.

Soil Amendment Formula

The following formula is used to calculate the amount of soil amendment needed for a specific area.

SA = (A * D * R) / 1000


  • SA is the soil amendment needed (cubic yards) A is the area to be amended (square feet) D is the desired depth of amendment (inches) R is the rate of amendment (pounds per cubic yard)

To calculate the amount of soil amendment needed, multiply the area to be amended by the desired depth of amendment and the rate of amendment. Then divide the result by 1000 to convert the units to cubic yards.

What is a Soil Amendment?

A soil amendment, also known as a soil conditioner, is a material added to soil to improve its physical properties, such as water retention, permeability, water infiltration, drainage, aeration, and structure. The goal is to provide a better environment for roots to grow, making plants healthier, more robust, and more productive. Amendments can be organic or inorganic, including compost, peat, manure, straw, lime, gypsum, and others.

How to Calculate Soil Amendment?

The following steps outline how to calculate the Soil Amendment:

  1. First, determine the area to be amended (A) in square feet.
  2. Next, determine the desired depth of amendment (D) in inches.
  3. Next, determine the rate of amendment (R) in pounds per cubic yard.
  4. Next, gather the formula from above = SA = (A * D * R) / 1000.
  5. Finally, calculate the Soil Amendment needed (SA) in cubic yards.
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Area to be amended (A) = 500 square feet

Desired depth of amendment (D) = 6 inches

Rate of amendment (R) = 10 pounds per cubic yard