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GhostScope

Can iPhone detect magnets?

Yes, for magnetic materials. Your iPhone's magnetometer, the sensor behind the Compass app, reacts to magnets and to magnetic metals like steel and iron. GhostScope turns that into a live number you can watch climb as you get closer: open EMF Meter, tap Calibrate away from the magnet, then move the phone toward it.

3 min read · Updated 2026-09-26

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What the magnetometer actually reacts to

A magnetometer measures magnetic field strength, not metal in general. It reacts strongly to permanent magnets and to ferromagnetic metals (steel, iron, nickel), because those either produce a magnetic field or distort the one around them. Non-magnetic metals are a different story. Aluminum, copper, brass and most stainless steel can sit right next to the phone and the reading won't budge.

GhostScope reads that sensor 20 times a second and shows the result as a number in µT or mG, a ring gauge and a 5-LED bar. Watching it rise and fall as you move the phone tells you a lot more than staring at one frozen figure ever would.

How to find a magnet with GhostScope

  1. Take the phone out of any case that has magnets built in, and set aside MagSafe accessories. They swamp the reading before you even start.
  2. Open GhostScope and tap the EMF Meter tile.
  3. Tap Start Hunt, hold the phone still somewhere away from the object you're checking, and tap Calibrate. The current field becomes your zero point.
  4. Move the phone slowly toward the spot you suspect. Keep the same orientation as you move; turning the phone changes the reading on its own.
  5. Watch the number and the LED bar climb. The closer and stronger the magnet, the higher it goes.

Worked example

Calibrated at 48.3 µT in the middle of a room, then moved close to a magnetic source, the raw reading climbs to 131.7 µT. GhostScope subtracts the 48.3 µT baseline and, at the default sensitivity of ×1.0, shows 83.4 µT (834.0 mG), which lights LEVEL 4 of 5 on the bar. Move the phone away along the same path and the number falls back toward 0.0 µT as you return to where you started.

What it can't do

  • It won't find aluminum, copper, brass or most stainless steel. A magnetometer only sees magnetic materials, not metal in general.
  • It gives you strength, not direction: a magnetometer can't tell you which way a magnet is, only how strong the total field is at that spot.
  • There's no fixed distance at which a magnet 'registers'. A strong magnet shows up further away than a weak one, so compare the trend as you move, not a single number.
  • It isn't a stud finder. Studs are usually found by density or the nails and screws in them, and only shows up here if that metal happens to be magnetic.

Questions and answers

Can iPhone detect magnets?
Yes. Its magnetometer, the sensor behind the Compass app, measures magnetic field strength and reacts to magnets and magnetic metals. GhostScope shows that reading live, so you watch it change as you move the phone rather than guessing.
Can iPhone detect all metal, like aluminum or copper?
No. The magnetometer only reacts to magnetic materials: magnets, steel, iron. Aluminum, copper, brass and most stainless steel don't move the reading at all.
How close does a magnet need to be to show up?
There's no fixed distance; it depends on how strong the magnet is. Calibrate first, then move the phone slowly toward the spot and watch the number rise, rather than expecting a specific reading at a specific distance.
Is this the same as a metal detector or stud finder app?
No. Those tools, and their underlying tech, differ from a magnetometer reading. GhostScope only shows magnetic field strength, so it finds magnets and magnetic metal, and misses non-magnetic metal entirely.

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