The app warns about the fact that it is not as good as a professional device, but I do not agree. If you take an optimal uninterupted reading of about 30secs, preferbly more, it is as good as any other device, for measuring bpm's, used by doctors and nurses. There is enough processing power and digital accuracy in an iPad, as there is in a dedicated medical device. Some of them are even made of cheaper, more inferior, components then found in iPad's and iPhones.