Rotating electric currents create magnetic fields. Magnetometer detects and measures these fields near you. The Earth's magnetic field value is around 25 to 65 μT (0.25 to 0.65 gauss). This is the value that Magnetometer has always as a default.

The app can be used as a metal detector to detect metal objects such as nails inside walls etc.

WHO's suggested guideline for magnetic field strength for public is 100 µT from 30 cm distance. A person moving within a field above 2 T can experience sensations of vertigo and nausea and sometimes a metallic taste in the mouth and perceptions of light flashes. The recommended limits are time-weighted average of 200 mT during the working day for occupational exposure with a ceiling value of 2 T. A continuous exposure limit of 40 mT is given for the general public.