How long does a magnet stay a magnet? The honest answer: decades. A well-made, coated neodymium magnet will outlast most of the machines it goes into — 30 to 50 years is a conservative expectation, and the measured data supports it. But there are two conditions: keep it cool, and keep it protected from moisture.
Magnets barely age at all — normally
Once a magnet is magnetized, its strength is remarkably stable. Left at room temperature, a good sintered NdFeB magnet loses less than one percent of its flux over decades. Researchers have tracked samples for over twelve years and project the loss at fifty years to be only around one percent.
The two real enemies
Heat. High temperature accelerates aging dramatically. Every magnet grade has a working temperature limit — stay below it and the magnet holds its strength; exceed it and it starts losing power, permanently. See temperature behaviour.
Corrosion. This is the real killer. Bare sintered NdFeB rusts in ordinary humid air — in one long-term study, uncoated magnets started showing rust after about six years, and the flux loss sped up from there. A good coating — nickel, zinc or epoxy — stops this almost completely. See coatings and corrosion.
What actually wears out?
| Aging mechanism | Effect | Main protection |
|---|---|---|
| Time alone | Tiny, slow loss | None needed — decades of life |
| Heat | Loss accelerates sharply | Stay below working temperature |
| Corrosion | Rust spreads, loss speeds up | Coatings, sealing, dry environment |
The lifetime rule
Keep a coated magnet cool and dry, and it will basically last forever — certainly longer than the product around it. When a magnet "dies" early, the cause is almost always overheating or rust, not old age.
Read on: how a magnet remembers its direction → · coatings explained →