How many cfms are there in a 20x25 return grill?

The CFM (cubic feet per minute) capacity of a 20x25 return grill depends on several factors, including the grill's design, the static pressure in the duct system, and the type of filter used. However, a general estimate is that a standard 20x25 return grill can handle approximately 800-1200 CFM. It's best to consult manufacturer specifications or perform detailed calculations for precise airflow needs in a specific HVAC system.