Magnetometer・Magnetic Field

Magnetometer turns the sensor already inside your phone into a readable instrument. Calibrate a baseline where you are standing, then watch how far the magnetic field moves away from it — live, in microtesla (µT).

How to read it
• The large number is the deviation from your calibrated baseline in µT, not an absolute field value
• An arc gauge steps through four states: Weak, Moderate, Strong and Peak
• A rolling waveform shows how the field has changed over the last few seconds
• The raw X, Y and Z axis values sit under the gauge, also in µT

Peaks you can feel
• A local peak — a rise followed by a fall — sets off a full-screen flash and haptic feedback
• A beep repeats faster and grows louder as the signal strengthens, so you can keep your eyes on the phone rather than the screen

Control the measurement
• Calibration sets your local baseline and rates it Excellent, Good, Fair or Poor
• Four sensitivity levels change how strongly the normalised signal is scaled
• High Precision filters noise harder: stronger smoothing, a stricter peak threshold and a longer debounce. Fewer false peaks and a slightly slower response — it does not amplify the signal
• Stop a scan yourself and it is kept as a summary with peak count, duration, mode and calibration quality. Up to 100 summaries stay on your device

What people measure with it
• Whether a screwdriver, scissors or a drill bit has picked up magnetisation
• How strong different fridge magnets, speaker magnets or bag clasps really are
• How the field around a running motor, speaker or appliance falls away with distance
• Whether a phone case, card wallet or stand has a magnet inside it
• Physics coursework and classroom demonstrations that need a live µT figure
• Plain curiosity about what the magnetic sensor in your handset actually reports

Why the reading is relative
Most magnetometer apps print one absolute number and leave you to guess whether it is high. This one asks you to calibrate first, then reports the deviation from that baseline — so the figure answers "how much has the field changed here", not "what is the field somewhere on Earth". The waveform, the four strength states and the peak flash all describe that same measured signal, and the app stays explicit about what it cannot tell you.

Getting a clean reading
• Calibrate away from metal, magnets and electronics
• Move the phone slowly and steadily
• Take off cases containing metal or magnets
• Recalibrate when you move to a different room or surface

What this app does not do
Magnetometer reports what the sensor reads. It cannot tell you what caused a reading, and it does not identify magnetic sources, objects, materials or where they are. It is not a stud finder, a wall scanner or a metal detector, and it makes no claim about anything behind a wall or any other surface. Readings depend on your handset's magnetometer and on nearby interference — treat them as a relative guide, not as a professional measuring instrument or a structural sur