Your iPhone has a built-in barometer — Here's how to use it

Did you know your iPhone secretly contains a barometer? Since 2014, this feature has been quietly integrated into most models, although the first-generation iPhone SE remains an exception. Essentially, a barometer measures atmospheric pressure, which changes as you ascend or descend in elevation. Higher altitudes mean lower pressure, and vice versa.

While this property might seem esoteric, it actually plays a key role in determining your elevation relative to sea level. The data isn't perfect, as weather fluctuations can also influence air pressure, but it serves as a reliable overall indicator. Apple never marketed the barometer as a standalone feature. Instead, it blends the data with other inputs like GPS and weather reports to calculate elevation.

Fitness apps, for instance, can use this information to track your steps and stair climbing accurately. However, Apple hasn't bundled the sensor into a dedicated app. Instead, developers can access the barometric and altitude data through Core Motion, enabling them to incorporate it into various fitness and outdoor apps. It's worth noting that Apple's built-in Weather app doesn't pull data from the barometer.

Instead, it relies on external sources. To get direct measurements from your iPhone's barometer, you'll need to use a third-party app that explicitly supports it. When selecting an app, look for descriptions that explicitly state they utilize the built-in barometer. Some popular choices include "Barometer & Altimeter & Thermo" and "My Altitude."

Both are free apps with high ratings, offering detailed information derived from the iPhone's on-device sensors.