Determine the flow rate of your sink:

1. Calculate the capacity of the sink in cubic inches (measurements of one compartment), and multiply that total by the number of compartments:
   
   
   Length (In.) x Width (In.) x Depth (In.) = Cubic In.
   
   
2. Convert the capacity from Total cubic inches to gallons per minute (GPM):
   
   
   Number of Compartments ÷ 231 = GPM
   
   
3. Adjust for displacement (displacement takes into consideration the actual useable capacity of your sink):
   
   
   GPM x 0.75 = GPM* x 2 = Flow Rate Capacity (lbs.)
* The resulting GPM is the required flow rate to drain the sink in one minute. You would then choose a grease trap with a GPM flow rate close to this number.

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If Draining Multiple Sinks Into One Grease Trap

1. Determine the flow rate for each sink to be serviced by the grease trap using the same calculations as a single sink.
2. Add together 100% of the largest flow rate, 50% of the second largest, and 25% of all others.
3. The result is the recommended flow rate (in GPM) of the grease trap.