Learn how to easily measure magnetic field. With today's smart phone technology, all you need to measure the strength of any magnetic field is built right into most phones.

Both iPhones and Android Phones allow measurement of magnetic fields using only the phone and a free app. There are several apps available to measure magnetic field. The iPhone options did not appear as easy to use as the Android options. For this reason this article will focus on how to measure magnetic field with an Android Phone. The phone we used for testing is the Samsung Galaxy Note 3. It has nearly the same sensors as the Samsung Galaxy S4 and Galaxy S5 phones. The Galaxy S4 has a Geomagnetic Sensor which detects magnetic field intensity. The Galaxy Note 3 has a Yamaha YAS532 Magnetometer sensor. These sensors are used with the built-in accelerometer to find the position of the Earth's true north so the phone knows its orientation so it can adjust the screen position. The phone also uses this sensor to help find its position, even if the GPS feature is turned off. The magnetic sensors, of course can do much more. The app-makers tapped into this power to provide the raw magnetic field data to the user.