When performing chest compressions during CPR on an adult, you need to press down at least 5 centimeters (2 inches) and up to a maximum depth of 6 centimeters (about 2.4 inches). This means pressing hard and fast to a depth of 5 to 6 cm, or about one-third the depth of the chest. It is important to allow the chest to fully recoil after each compression without lifting your hands off the chest. The compressions should be done at a rate of 100 to 120 compressions per minute.
For children, the recommended depth is about one-third the depth of their chest, roughly around 5 cm (2 inches).
This depth helps to ensure effective circulation of blood during cardiac arrest while minimizing injury risk, though some injury may occur and is acceptable to save a life.
