One or more computing devices, systems, and/or methods for calibrating barometric sensors and/or determining altitudes of devices are provided. In an example, a device is determined to be outdoors. In response to determining that the device is outdoors, a calibration process associated with a barometric sensor of the device is performed. The calibration process includes performing one or more barometric measurements using the barometric sensor to determine one or more barometric pressure measures, determining one or more locations of the device, wherein the one or more locations are associated with the one or more barometric measurements, and determining a barometric offset based upon the one or more barometric pressure measures and one or more reference values. An adjusted barometric pressure and/or an altitude of the device is determined based upon a first barometric pressure measure and the barometric offset.