Desicant Dehumidifier Calculator ACH ➜ Required CFM (1–4 ACH) Length (ft) Width (ft) Height (ft) OR Volume (ft³) Desired ACH: 2.0 1 ACH 2 ACH 3 ACH 4 ACH Clear Formula: CFM = (ACH × Volume) / 60 Room Volume — Required CFM @ ACH — ACHCFM