Enter the total organic matter (lbs-BOD5/gal), the design flow (gal/day), and the area (ft^2) into the Organic Loading Rate Calculator. The calculator will evaluate the Organic Loading Rate. 

Organic Loading Rate Formula

The following formula is used to calculate the Organic Loading Rate. 



  • OLR is the Organic Loading Rate (lbs-BOD5/ft^2/day)
  • OM is the total organic matter (lbs-BOD5/gal) 
  • DF is the design flow (gal/day) 
  • A is the area (ft^2) 

How to Calculate Organic Loading Rate?

The following steps outline how to calculate the Organic Loading Rate.

  1. First, determine the total organic matter (lbs-BOD5/gal).
  2. Next, determine the design flow (gal/day). 
  3. Next, determine the area (ft^2). 
  4. Next, gather the formula from above = OLR = OM*DF/A.
  5. Finally, calculate the Organic Loading Rate.
  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.

total organic matter (lbs-BOD5/gal) = 500

design flow (gal/day) = 3000

area (ft^2) = 20

OLR = OM*DF/A =  ?