In accordance to the International System of Units (SI system), Noctua specifies volumetric flow rate (airflow) using the SI unit of cubic metres per hour (m³/h). The SI unit can easily be converted to cubic feet per minute (CFM): One m³/h equals ~0.589 CFM and one CFM is ~1.699 m³/h. 

For convenient conversion, you can use the tool below: