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To Find Your Heart Rate, Stare At This App

Even if you can’t think of any reason why you would want to check your heart rate, this app’s tech is cool enough to make it worthwhile to determine your beats per minute.

Your iPhone’s health monitoring capabilities just got a little more advanced. Cardiio, an app built by scientists from MIT, can quickly check your heart rate. All you have to do is stare at the phone—no touching required.

We first discovered Cardiio at Rock Health’s demo day, where the health startup incubator showed off the creations of its latest class. Like many of its Rock Health peers, Cardiio takes today’s technology (and ideas) one step further.

There are already apps that allow users to check their pulse by putting a finger over the iPhone camera, measuring changes in light intensity that correspond to blood pulses. Cardiio takes a similar tack—albeit one that’s more hands-off. The app measures the amount of light reflected off the face, which matches up to the amount of blood pumped into the face (every time the heart beats, more blood is pumped).

It’s simple to use: just stare at the app and wait for it to measure your heart beat. You can keep a running log of your heart rate at different hours and days. Cardiio also offers helpful statistics, revealing how your heart rate compares to an elite athlete and the average citizen. A lower resting heart rate generally indicates better physical fitness, though your heart rate may vary wildly throughout the day—according to the app, mine jumped from 59 to 81 and back down to 61 within the span of a couple hours.

In peer-reviewed literature, Cardiio’s heart rate measurements have shown to be within 3 beats per minute of a clinical pulse oximeter—the gold standard. That makes it more than accurate enough for non-medical uses (it’s not FDA approved).

Cardiio is available in the app store now for $4.99.