Searching the play store for emf detector shows a bunch of apps that can measure the electromagnetic radiation level and they do seem to somehow work.

What is the operating principle behind these apps and what kind of sensors are they using?

What level of accuracy these sensors provide and how do they compare to dedicated EMF detectors which sell online starting with ~$7?

In the Android docs I see: SENSOR_TYPE_MAGNETOMETER, SENSOR_TYPE_MAGNETIC_FIELD and SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED — can these possibly be used to measure EMF radiation levels and if so then which ranges are supported?


  • As I have previously mentioned that Magnetic field and Electro-magnetic field differ hugely. The two of them are not identical at all. Magnetic field is one created by 'moving charges' The intersection (almost) between a magnetic and an electric field is EMF. A magnetometer cannot detect or measure an Electromagnetic field, and viceversa. Our phones use EMF to receive and transmit signals, that means that they can do well at detecting them but they are specifically designed to work in frequency ranges of your network type (2G, 3G, 4G, etc) which usually range from 600Mhz to 2.2Ghz. Oct 29, 2019 at 13:42

1 Answer 1


The question does not only apply to android phones, but to all mobile devices. Our mobile devices use EMF to communicate. Mobile phones are, by definition, devices that can detect EMF since their ability to communicate depends on radiofrequency fluctuations in electromagnetic fields. Our devices, especially smartphones, which are extremely reliant on internet services emit a huge amout of EMF radiation. That should imply that mobiles can precisely detect and manipulate EMF, right? No. Our phones are designed to work with only specific frequencies, from about 800 to 2.2GHz, so it is quite unlikely that a mobile phone can detect general fluctuations in EMF.
Now, the creator of the app might tell you that it uses magnetic sensor, and you might think that EMF can be detected using a magnetic sensor, since it is also (partly) a magnetic wave, but you cannot. EMF exists when a wave has both electric as well as magnetic parts.

  • So what you are saying is that those 'EMF' apps in fact only measure magnetic field levels and not electromagnetic intensity, no?
    – ccpizza
    Oct 28, 2019 at 17:46
  • @ccpizza Mobile phones can do well at detecting fields, but they are not built for measuring them. Some apps might take the help of magnetometer but they are also limitedly accurate as they heavily rely on earth's gravity. Oct 28, 2019 at 18:00

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