About the readings

What this app measures

Your phone contains a 3-axis magnetometer used for the compass. This app reads its output and displays the total magnetic field strength as a single number, in microtesla (µT) or milligauss (mG).

What it does NOT measure

• Radio-frequency radiation (Wi-Fi, cellular, 5G, Bluetooth)
• Microwave-oven leakage
• 50 / 60 Hz AC mains fields with full accuracy — phone sensors sample too slowly
• Ionising radiation of any kind

For those you need dedicated hardware (RF meter, gaussmeter, Geiger counter).

iPhone limitation

Safari on iOS does not expose raw magnetometer data to web pages. On iPhone, this app falls back to compass-instability mode — it watches for rapid jitter in the phone's reported heading, which can indicate nearby magnetic disturbance from appliances, transformers or speakers. The number it shows is a relative indicator, not a true µT reading. For accurate readings, use an Android phone with Chrome, or consider a dedicated EMF meter.

How to use it

1. Stand in the middle of a quiet room, away from appliances.
2. Tap Start scan, then Calibrate — this sets your local baseline (typically 25–65 µT outdoors, the Earth's field).
3. Walk slowly around the room. The gauge turns yellow at 20%+ above baseline and red above 100%.
4. Tap Log with a label to save notable spots for later review.

A note on EHS

Electromagnetic hypersensitivity (EHS) describes symptoms people attribute to electromagnetic field exposure. The World Health Organization and other bodies have published guidance on the subject. This app is a personal awareness tool, not a medical device, and its readings should not be used to diagnose anything.