Yes – a good sheet uses hydraulic diameter (D_eq = 4A/P) to convert rectangular to round equivalent.
But the full engineering formula is:
[ ESP = (SP_supply + SP_return) - (PD_filter + PD_coil + PD_grille + PD_elbow) ] esp calculation hvac excel sheet
At installation, after filter change type, after duct modifications, and annually for maintenance. Yes – a good sheet uses hydraulic diameter