Enter the harvested water (gal) and the rainfall depth (in) into the Calculator. The calculator will evaluate the Catchment Area. 

Catchment Area Formula

CA = HW / RFD / .623


  • CA is the Catchment Area (ft^2)
  • HW is the harvested water (gal)
  • RFD is the rainfall depth (in)

To calculate the Catchment Area, divide the harvested water by the rainfall depth, then divide the result by .623.

How to Calculate Catchment Area?

The following steps outline how to calculate the Catchment Area.

  1. First, determine the harvested water (gal). 
  2. Next, determine the rainfall depth (in). 
  3. Next, gather the formula from above = CA = HW / RFD / .623.
  4. Finally, calculate the Catchment Area.
  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.

harvested water (gal) = 45

rainfall depth (in) = 34