Enter the volume of water held in the soil after drainage and the total volume of the soil into the calculator to determine the field capacity. This calculator can also evaluate any of the variables given the others are known.

Field Capacity Formula

The following formula is used to calculate the field capacity.

FC = (VW / VS) * 100

Variables:

  • FC is the field capacity (%)
  • VW is the volume of water held in the soil after drainage (m³)
  • VS is the total volume of the soil (m³)

To calculate the field capacity, divide the volume of water held in the soil after drainage by the total volume of the soil. Multiply the result by 100 to convert it to a percentage. This will give the percentage of the soil volume that is filled with water, which is considered to be at field capacity.

What is a Field Capacity?

Field capacity is a term used in soil science to describe the amount of soil moisture or water content held in soil after excess water has drained away and the rate of downward movement has decreased. This usually takes place 2–3 days after rain or irrigation in pervious soils of uniform structure and texture. The water that is held by the soil against the force of gravity is considered to be at field capacity.

How to Calculate Field Capacity?

The following steps outline how to calculate the Field Capacity.


  1. First, determine the volume of water held in the soil after drainage (VW) in cubic meters (m³).
  2. Next, determine the total volume of the soil (VS) in cubic meters (m³).
  3. Next, use the formula FC = (VW / VS) * 100 to calculate the Field Capacity.
  4. Finally, calculate the Field Capacity as a percentage (%).
  5. 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.

volume of water held in the soil after drainage (VW) = 10 m³

total volume of the soil (VS) = 50 m³