How to Demagnetize a Magnet: Methods, Materials and Safety

A magnet can be demagnetized by disrupting or reversing the alignment of its magnetic domains. The most common methods are heating, an alternating magnetic field (AC degaussing), a sufficiently strong opposing magnetic field, or severe mechanical shock. Which method works depends heavily on the material: soft magnetic steels are relatively easy to demagnetize, while high-coercivity permanent magnets such as neodymium (NdFeB) and samarium cobalt (SmCo) are much harder to demagnetize intentionally.

For permanent magnets, demagnetization may be partial, complete, or irreversible. Before attempting it, determine whether the goal is to remove residual magnetism from a steel part, reduce the field of a permanent magnet, or permanently destroy the magnet’s magnetic performance.

If your goal is to prevent accidental permanent loss rather than cause it, use the Magnet Temperature Derating Calculator for thermal screening and the Magnet Demagnetization Calculator for coercivity, geometry and operating-point risk.

How Do You Demagnetize a Magnet?

Method	Best suited for	Permanent magnet?	Main limitation
AC degaussing	Tools, steel parts, soft magnetic materials	Sometimes, if the available field is strong enough	May be insufficient for high-coercivity NdFeB or SmCo
Heating	Permanent, destructive demagnetization	Yes	Can damage coating, dimensions and material properties
Opposing magnetic field	Controlled partial or full demagnetization	Yes	Requires field strength near or beyond the material’s coercivity
Mechanical shock	Some low-coercivity magnets and magnetized steel	Unreliable for modern rare-earth magnets	Can crack or shatter brittle magnets
Controlled magnetizing pulse	Industrial magnetic processing	Yes	Requires specialized magnetizing/demagnetizing equipment

1. Demagnetizing With an Alternating Magnetic Field

AC degaussing is one of the most useful non-destructive methods for removing residual magnetism from ferromagnetic tools and components. A demagnetizing coil creates a magnetic field that repeatedly reverses direction. If the amplitude is gradually reduced to near zero, the magnetic domains settle into a more randomized state and the net residual field decreases.

This works very well for many steels, tools, fixtures and components with relatively low coercivity. The usual process is to place the part inside or near the demagnetizing coil and gradually reduce the field, often by slowly moving the part away while the coil remains energized.

Important limitation: a small bench-top demagnetizer that works well on a screwdriver may not generate enough reverse field to fully demagnetize a high-coercivity neodymium magnet.

2. Demagnetizing a Magnet With Heat

Heating reduces magnetic performance because thermal energy disrupts magnetic-domain alignment. If a permanent magnet is heated sufficiently, it can experience partial or permanent magnetic loss.

Two different temperature concepts matter:

Maximum operating temperature: above this range, a magnet may experience irreversible losses even though it remains far below its Curie temperature.
Curie temperature: the temperature at which ferromagnetic ordering collapses and the material loses its spontaneous magnetization.

Heating above the Curie temperature can demagnetize a material, but it is generally a destructive industrial method, not a recommended field procedure. High heat can oxidize the magnet, damage nickel or epoxy coatings, alter adhesives, create fumes, change dimensions, and permanently affect the material.

For grade-specific temperature limits, see our magnet temperature and heat-tolerance guide.

3. Using an Opposing Magnetic Field

A permanent magnet can be partially or fully demagnetized by applying a magnetic field in the direction opposite its existing magnetization. To cause substantial irreversible loss, the reverse field must be strong enough relative to the magnet material’s coercivity.

This is why magnet grade matters. High-coercivity grades such as many H, SH, UH, EH and AH neodymium grades are specifically designed to resist demagnetizing fields better than standard grades.

In a controlled industrial process, a magnetizer can apply a reverse pulse with a known field strength. Depending on the amplitude, the magnet can be partially demagnetized, brought near zero net magnetization, or magnetized in the opposite direction.

See our neodymium grade and coercivity chart and Magnet Demagnetization Calculator for related engineering guidance.

4. Can Hitting or Dropping a Magnet Demagnetize It?

Mechanical shock can sometimes reduce magnetization, but it is not a controlled or recommended demagnetization method. The effect is much more relevant to some older or lower-coercivity magnetic materials than to modern high-coercivity rare-earth magnets.

Neodymium and samarium-cobalt magnets are also brittle. Hitting, hammering or intentionally dropping them can cause chipping, cracking or shattering long before it produces a useful, predictable level of demagnetization.

If the goal is controlled residual-field reduction, an AC demagnetizer or properly designed magnetic fixture is normally preferable.

5. Industrial Pulse Demagnetization

Industrial magnetizing systems can apply controlled magnetic pulses to magnetize, reverse or reduce the magnetization of permanent magnets and assemblies. This provides much better control than improvised methods because the applied field can be engineered relative to the material’s coercivity and the magnetic circuit.

For complex assemblies, multipole magnets, motors and sensor systems, controlled pulsing may be the only practical way to achieve a specific residual magnetic state.

Can You Demagnetize a Neodymium Magnet?

Yes, but neodymium magnets are intentionally resistant to demagnetization. A fully magnetized NdFeB magnet usually requires substantial heat or a sufficiently strong reverse magnetic field to produce major permanent loss.

The exact resistance depends on the grade, geometry, temperature and operating point. Standard grades may be more vulnerable to heat and reverse fields, while high-coercivity grades are designed for greater resistance.

Simply rubbing a neodymium magnet with another magnet, placing it next to a weak opposite pole, or striking it lightly will generally not provide controlled demagnetization.

Can You Demagnetize a Magnet Without Damaging It?

Sometimes. For magnetized steel parts and soft magnetic materials, AC degaussing can remove residual magnetism without materially changing the component.

For a hard permanent magnet, the answer depends on the required final condition. A controlled reverse magnetic field can reduce magnetization without physically damaging the part, but the process requires suitable equipment and a known magnetic specification.

Heating and mechanical shock are much more likely to create permanent physical or material damage.

Why Do Magnets Become Demagnetized Accidentally?

Permanent magnets can lose magnetic performance unintentionally through:

Excessive temperature or prolonged exposure near the material’s thermal limit
Strong opposing magnetic fields
Poor magnetic-circuit design that places the magnet at an unfavorable operating point
Geometry with a low permeance coefficient, especially thin magnets magnetized through the thin dimension
Improper storage or assembly conditions
Radiation or extreme environments in specialized applications

For permanent-magnet designs, the relevant question is often not “how do I demagnetize it?” but “how do I prevent irreversible demagnetization during operation?”

Demagnetizing Tools vs. Demagnetizing Permanent Magnets

These are different engineering problems. A magnetized steel screwdriver has relatively low coercivity and can usually be degaussed easily. A sintered neodymium magnet is a hard magnetic material specifically manufactured to retain magnetization and resist reverse fields.

Object	Typical approach
Magnetized screwdriver or hand tool	AC demagnetizer
Machined steel component with residual magnetism	AC coil, tunnel demagnetizer or specialized degaussing system
Neodymium permanent magnet	Controlled reverse field or destructive thermal process
SmCo permanent magnet	Controlled high-field process; difficult due to high coercivity
Alnico permanent magnet	Reverse field can be effective because coercivity is comparatively low

How Do You Know If a Magnet Has Been Demagnetized?

The best method is to compare a defined magnetic measurement before and after the process. Depending on the specification, this may involve:

Surface gauss measurement at a fixed point
Flux measurement with a fluxmeter and coil
Pull-force testing under controlled conditions
Magnetic moment measurement
Functional testing inside the final assembly

A simple “does it still stick?” test is not sensitive enough for most engineering or quality-control applications. Read How Gauss Measurement Works for proper field-measurement context.

Safety Considerations

Intentional demagnetization can involve high temperatures, strong magnetic fields, high-current equipment and brittle magnetic materials. For production or laboratory work:

Do not heat coated permanent magnets with an open flame.
Do not strike or crush brittle rare-earth magnets as a demagnetization method.
Keep strong fields away from sensitive electronics, magnetic media and medical devices.
Use fixtures and guarding when working with large permanent magnets or high-field magnetizing equipment.
Follow the equipment manufacturer’s electrical and thermal safety procedures.

Frequently Asked Questions

How can you demagnetize a magnet?

The main methods are an alternating magnetic field, heating, or a sufficiently strong opposing magnetic field. The best method depends on the magnet material and whether the process must be non-destructive.

Can you permanently demagnetize a magnet?

Yes. A permanent magnet can experience irreversible demagnetization if it is exposed to sufficient heat or a strong enough reverse magnetic field. Whether it can later be remagnetized depends on whether the material itself was physically or metallurgically damaged.

Does heat demagnetize magnets?

Yes. Elevated temperature reduces magnetic performance, and sufficiently high temperatures can cause irreversible loss. Heating to the Curie temperature destroys ferromagnetic ordering, but this is generally a destructive process for a finished magnet.

Does dropping a magnet demagnetize it?

It can affect some magnetic materials, but it is unreliable and may physically damage the magnet. Modern neodymium magnets are more likely to chip or crack than to become predictably demagnetized from ordinary impact.

Can a demagnetized magnet be magnetized again?

Often yes, if the magnetic material has not been damaged by excessive heat, oxidation, cracking or other physical changes. Industrial magnetizers can re-magnetize many permanent magnets by applying a sufficiently strong field.

What is the best way to demagnetize a steel tool?

An AC demagnetizer is usually the most practical method. The alternating field is gradually reduced, leaving the steel with much lower residual magnetism.