CPR Trainer is a training software for the chest compression Cardio Pulmonary Resuscitation (CPR) using sensors in an Android smart phone. The motion of chest compression is estimated with mainly accelerometer sensors in Android phone.

Chest compression is executed by pumping the chest to circulate oxygenated blood throughout the body. Three factors of chest compressions are crucial: hand placement, depth of compression, and compression rate. CPR guideline states to compress the adult chest at a rate of at least 100 compressions per minute, with a compression depth of at least 2 inches/5 cm, and at "the middle of the chest" by AHA guideline 2010.

The aim of the developed system is to estimate the compression action and to provide a feedback to follow the guideline above. Our software was designed to target Android 2.3 and higher.