The pattern of the binding produces the characteristic S shape of the curve relating PO₂ to Hb-O₂ saturation (Fig 1a).

At normal arterial PO₂ of 13 kPa, saturation of Hb is near-complete (Fig 1b).

At rest, approximately 25% of the available O₂ is extracted by the tissues, resulting in a venous saturation of 75% and a PO₂ of around 5.3 kPa.

The P₅₀ is the PO₂ at which the Hb-O₂ saturation is 50%, normally around 3.5 kPa. It is a reference point that describes the position of the curve and changes as the curve moves under different conditions.