The force required to depress keys to the snap point should be in the range between a minimum of 0.25 N (0.9 ounces) and a maximum of 1.5 N (5.4 ounces); the preferred key force is in the range between 0.5 N (1.8 ounces) and 0.6 N (2.2 ounces).
Additional Information: For repetitive keying tasks, the force required for key displacement should be in the range between a minimum of 0.3 N (1.1 ounces) and a maximum of 0.75 N (2.7 ounces). Variability of the key-activation force among different alphanumeric keys should be minimized. Static force measurements should be made at the center of the keys and at the corners. When measured at the corners, there should be minimal binding (actuating force increase) at the corner locations.100, 5908