FIELD SCANNER: EMF Detector

FIELD SCANNER turns your phone's magnetometer into a magnetic field meter and EMF detector. Bring the phone close to a fridge, a socket under load or a microwave oven and watch the reading change in microtesla (µT) as you move.

Next to the number you see what it means. The Earth's own field is 25–65 µT, so every reading carries a label: below background, Earth's field, elevated or high. A hint under the number names the closest everyday example, such as a fridge up close. A separate screen lists typical values for household appliances, with the source named for each one.

What you can check
• How strong the magnetic field is next to a fridge, a microwave oven, a socket under load or under a power line
• How quickly it drops as you step back
• Steel and magnets close to the phone, such as a screw under thin plasterboard or the magnet in a phone case
• Whether one room differs from another: save the background as a reference and watch the difference

On the main screen
• A large reading in µT or milligauss (mG) with a word for the level
• An analogue needle and a six-dot light bar
• A one-minute chart with your threshold drawn as a dashed line
• The X, Y and Z axes shown separately
• Minimum, average and maximum; Reset clears them and Hold pauses the reading
• Sensor status and accuracy, always visible

Sound, records and widget
• A beep when the field goes above or below a threshold you set
• Clicks that come faster as the field gets stronger, so you can move the phone along a surface without looking at the screen
• Record keeps a session of up to 30 minutes: chart, minimum, average, maximum, time and duration
• Share sends the reading with its minimum, average and maximum as text to any app
• A home screen widget shows the last reading and how long ago it was taken; tap it to open the meter

Before you measure, draw a figure of eight in the air with the phone. This calibrates the sensor. Then turn the phone slowly and go by the steadiest value. The sensor sits in one corner of the phone, and the metal inside the body shields it unevenly.

Good to know
This EMF detector works through the phone's magnetometer, and a magnetometer sees static and low-frequency magnetic fields. It does not see Wi-Fi, mobile signal or the microwaves inside an oven. Those are radio frequencies, and a phone cannot measure them. A microwave oven still gives a strong reading up close, from its transformer. In a quiet room you mostly see the Earth's field. A normal reading is the background, not a discovery, so the useful number is how far the reading rises above it.

The sensor's sensitivity is set at the factory and is not published. Use FIELD SCANNER to compare places and objects. It is not a certified instrument, and it does not judge effects on health.

If your device has no magnetometer, the app says so and shows no numbers. Most phones have one; some budget models do not.

Twenty saved sessions, sharing, the scale, the chart and the threshold with sound are free. A one-time purchase adds report export and keeps up to 50 saved sessions instead of 20. There is no subscription.

The app has no ads and needs no account. It sends anonymous usage statistics, which you can turn off in settings.

Independent development: one person builds and maintains this app. A letter to support@markarov.dev is read by that person, not by a support desk.

Recent changes:
New look: a speedometer-style dial, the band of the reading as a word in a capsule, a segment bar under the number, minimum, average and maximum as tiles, and info and settings as icons in the top bar.
Saved measurements: share, export and delete are icons on each card, and delete asks first.
When you share a reading or a saved measurement, the last line is now a link to the app on Google Play.