How long will a magnet stay magnetized?
Sintered Nd-Fe-B magnets will remain magnetized indefinitely. They experience a miniscule reduction in flux density over time. As long as their physical properties remain intact, neodymium magnets will likely loose less than1% of their flux density over 100 years. Generally the magnet will experience a degradation in its physical properties, such as corrosion, prior to it demagnetizing because of age. However, heat and high magnetic fields can demagnetize these magnets.