It’s not so surprising to hear that an iPhone app can tell you your heart rate. What is surprising is that Cardiio can do it using the iPhone’s camera, and nothing else. The app uses the iPhone’s front-facing camera to analyze the amount of light reflected by your face. The developers discovered that when your heart beats, more blood is pumped into your face. The slight increase in blood volume ends causes your face to absorb more light. Then light is reflected more when the blood leaves your face.
By training the iPhone camera on your face, the app studies when light is absorbed and reflected to determine a pulse. While testing, Cardiio found the app accurately measures heart rate within three bpm of a clinical pulse oximeter. The app must be used in a well-lit environment. Your face should be well lit to avoid uneven illumination and backlight.
The Cardiio app stores your daily, weekly and monthly history on the personal dashboard, rates your fitness level based on your heart rate, compares your data to comparable data such as by age group. Cardiio also actually estimates your potential life expectancy.
Cardiio is available for $4.99 in iTunes .