Flexible Magnet Holding Force Explained: What Determines Real-World Performance?

How strong is flexible magnetic sheeting?

It sounds like a simple question, but flexible magnet holding force cannot be described accurately by thickness or a single strength number alone.

Two flexible magnetic materials of the same thickness can perform differently. Two suppliers can also publish different holding-force values that cannot be compared directly if their test methods, target steel or measurement units are different.

For flexible magnets, real-world holding performance depends on the complete magnetic system: material formulation, thickness, magnetization, pole pitch, target steel, air gap, surface contact, load direction, friction and test conditions.

Table of Contents

• 1. What Is Flexible Magnet Holding Force?
• 2. Holding Force vs Pull Force
• 3. Understanding Holding-Force Units
• 4. Why the Test Method Matters
• 5. How Thickness Affects Holding Force
• 6. Why Material Formulation Matters
• 7. Magnetization and Pole Pitch
• 8. Target Steel Is Part of the Magnetic System
• 9. The Air Gap Effect
• 10. Surface Contact and Flatness
• 11. Does More Surface Area Mean More Holding Force?
• 12. Pull-Off Force vs Vertical Holding
• 13. How to Compare Two Flexible Magnetic Materials
• 14. Selecting Holding Performance for an Application
• 15. Common Mistakes
• 16. Frequently Asked Questions

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1. What Is Flexible Magnet Holding Force?

Holding force is a measure of the magnetic attraction available between the flexible magnet and a compatible target surface under specified conditions.

For flexible magnetic sheeting, the target is commonly a ferromagnetic steel surface.

The important words are “under specified conditions.”

A holding-force value is not an independent property that remains identical regardless of how the material is used.

The measured result can depend on:

• magnetic formulation;
• material thickness;
• magnetization level;
• pole configuration and pole pitch;
• target steel;
• steel thickness;
• surface condition;
• air gap;
• contact area;
• direction of force;
• test equipment and procedure.

For an introduction to the construction of flexible magnets, see SSKC-026 — Flexible Magnetic Sheeting Explained.

2. Holding Force vs Pull Force

The terms holding force and pull force are sometimes used interchangeably in product literature, but the measurement conditions need to be understood.

A pull-off test generally measures the force required to separate the magnetic material from its target in a direction approximately perpendicular to the contact surface.

This is different from a vertical application where gravity tries to make the magnetic piece slide along the surface.

It is also different from peeling, where separation begins at an edge and progressively reduces the contact area.

3. Understanding Holding-Force Units

Flexible magnetic materials may be specified using different units depending on the manufacturer and test method.

Examples can include force relative to contact area, such as:

• grams per square centimetre (g/cm²);
• pounds per square foot (lb/ft²);
• or other force-per-area measurements.

Some technical data may instead report the force measured on a specific sample size.

These numbers should not be compared blindly.

Before comparing two specifications, determine:

• what was measured;
• the sample dimensions;
• the target material;
• the target thickness;
• whether the surfaces were in direct contact;
• the direction of the test;
• the test speed or procedure, when specified;
• whether the published result is typical, minimum or another specification.

4. Why the Test Method Matters

A magnetic holding-force specification is meaningful only in the context of its measurement method.

Imagine two flexible magnets tested by two different suppliers.

Supplier A may test against one steel thickness with clean direct contact. Supplier B may use a different steel plate, sample geometry or separation procedure.

Even if both publish results in g/cm², the numbers may not represent an equivalent test.

This is why professional comparison should consider both:

the measured value + the test conditions.

For purchasing, engineering or quality-control purposes, using a consistent test method is particularly important when qualifying alternative materials.

5. How Thickness Affects Holding Force

When otherwise similar flexible magnetic constructions are compared, increasing the magnetic material thickness generally provides more magnetic material per unit of area and can increase potential holding capability.

This is one reason 30 mil material may provide greater holding performance than comparable 20 mil or 15 mil material.

But thickness alone is not enough to predict performance.

A thicker product with a different formulation or magnetization configuration should not automatically be assumed to outperform every thinner product.

For a detailed thickness comparison, see SSKC-031 — 15 mil vs 20 mil vs 30 mil Flexible Magnetic Sheeting.

6. Why Material Formulation Matters

Flexible magnetic materials typically combine magnetic ferrite particles with a flexible polymeric binder.

The finished magnetic performance can be influenced by factors such as:

• magnetic particle loading;
• particle characteristics;
• ferrite system;
• binder system;
• particle orientation;
• manufacturing process;
• magnetization after production.

Therefore, two materials that both measure 20 mil thick may not provide identical magnetic performance.

The ferrite chemistry itself also does not determine the complete performance of the finished material. For more detail, see SSKC-028 — Strontium vs Barium Ferrite in Flexible Magnets.

7. Magnetization and Pole Pitch

Flexible magnetic sheeting is commonly magnetized with multiple alternating pole regions across the magnetized surface.

This multipole configuration is particularly useful for applications involving close contact with ferromagnetic steel.

The spacing associated with these repeating poles is commonly described as pole pitch.

Changing the pole configuration can change how the magnetic field is distributed near the surface.

As a result, two materials with similar thickness and formulation can still behave differently if their magnetization patterns are different.

Smaller pole pitch should not automatically be interpreted as greater holding force. Pole pitch must be considered together with material formulation, thickness, magnetization, target steel and working distance.

Learn more in SSKC-027 — Flexible Magnet Pole Pitch & Multipole Magnetization.

8. Target Steel Is Part of the Magnetic System

The flexible magnet does not work independently of its target.

The steel forms part of the magnetic circuit.

Holding performance can therefore change with:

• steel thickness;
• steel composition;
• surface flatness;
• coatings;
• surface condition;
• available contact area.

A very thin steel target may not interact with the magnetic field in the same way as a more suitable steel thickness.

This means that a holding-force specification measured against one target plate cannot automatically predict performance against every steel product.

9. The Air Gap Effect

Flexible magnetic materials commonly operate at very short working distances.

Anything that separates the magnet from the steel creates an effective air gap.

Examples include:

• paint;
• vinyl;
• laminate;
• protective film;
• adhesive layers;
• dirt;
• surface texture;
• unevenness;
• curvature.

An air gap can reduce magnetic interaction because the magnet is no longer working in the same direct-contact condition used for many published holding-force tests.

There is no single universal percentage that describes the loss for every flexible magnet.

The effect depends on the magnetic construction, pole geometry, gap distance and target.

For the broader engineering principle, see SSKC-012 — The Air Gap Effect.

10. Surface Contact and Flatness

Flexible magnets benefit from good surface contact.

A nominally large magnetic sheet does not necessarily have full effective contact if the target is:

• curved;
• textured;
• dirty;
• damaged;
• uneven;
• covered by thick coatings.

Wrinkles, trapped debris or lifted edges can also reduce effective contact.

This is particularly important for large magnetic graphics, where a small local separation may affect only part of the area but can also create an edge where peeling or lifting begins.

11. Does More Surface Area Mean More Holding Force?

Increasing effective contact area can increase the total available magnetic holding force when the material, target and contact conditions remain comparable.

However, total force should not always be calculated by simply multiplying a published force-per-area value by any desired area.

Large finished pieces introduce additional variables such as:

• uneven contact;
• surface curvature;
• material stiffness;
• load distribution;
• edge lifting;
• installation quality;
• environmental exposure.

A small laboratory sample can therefore provide useful material data without perfectly reproducing the behavior of a large finished graphic.

12. Pull-Off Force vs Vertical Holding

One of the most common mistakes is using a direct pull-off value as if it were automatically the maximum load that can be supported vertically.

In a vertical installation, gravity acts parallel to the surface.

Resistance to sliding depends significantly on friction.

A simplified conceptual relationship is:

Magnetic Normal Force + Surface Friction → Resistance to Sliding

But actual vertical performance can also be affected by:

• surface finish;
• contamination;
• load distribution;
• vibration;
• movement;
• peeling forces;
• leverage;
• temperature;
• environment.

There is therefore no universal conversion such as “vertical holding force equals a fixed percentage of pull force.”

Test the actual assembly in the orientation in which it will be used.

13. How to Compare Two Flexible Magnetic Materials

If you are comparing two products, do not begin with the largest published number.

Use a structured comparison.

Compare	Why It Matters
Magnetic thickness	Changes the amount of magnetic material per area
Material formulation	Can affect magnetic capability even at equal thickness
Magnetization / pole pitch	Influences near-surface field distribution
Holding-force unit	Values may use different reporting conventions
Test method	Different procedures can produce different results
Target steel	The target forms part of the magnetic circuit
Air gap	Separation can significantly affect performance
Load direction	Pull-off and sliding are different failure modes

14. Selecting Holding Performance for an Application

The required magnetic performance should come from the application, not from the catalog.

Start by identifying:

• finished piece dimensions;
• finished weight;
• target surface;
• orientation;
• air gap;
• environment;
• movement or vibration;
• expected service life;
• consequences of detachment.

Then evaluate candidate materials under representative conditions.

For non-critical labels or graphics, this may involve straightforward application testing.

For applications where detachment could create damage, injury or significant loss, the design and validation requirements should reflect those consequences.

For a complete selection process, see SSKC-032 — How to Choose Flexible Magnetic Sheeting for Your Application.

15. Common Mistakes

Mistake 1: Comparing only thickness

Thickness matters, but formulation and magnetization can also change performance.

Mistake 2: Comparing numbers without checking units

Different units can sometimes be converted mathematically, but this does not resolve differences in test methods.

Mistake 3: Ignoring the test method

A holding-force value without its measurement conditions provides an incomplete comparison.

Mistake 4: Ignoring target steel

The target is part of the magnetic circuit and can influence the measured result.

Mistake 5: Ignoring the air gap

Paint, laminates, texture and contamination can reduce effective magnetic interaction.

Mistake 6: Treating pull-off force as vertical load capacity

Vertical holding involves friction and potentially sliding, peeling and leverage.

Mistake 7: Assuming laboratory results equal finished-product performance

The finished assembly may introduce dimensions, curvature, coatings, movement and environmental conditions not represented in a material test.

16. Frequently Asked Questions

How strong is flexible magnetic sheeting?

There is no single strength value for all flexible magnetic sheeting. Holding performance depends on material formulation, thickness, magnetization, pole pitch, target steel, air gap, contact area, load direction and test method.

Is 30 mil magnetic sheeting stronger than 20 mil?

When otherwise similar constructions are compared under the same conditions, 30 mil material generally has more magnetic material per unit area and can provide greater potential holding capability. Different formulations or magnetization systems can change the comparison.

What does g/cm² mean for flexible magnets?

It is a way of expressing force relative to contact area. The number is meaningful only when the associated test method and conditions are understood.

Can I convert g/cm² to lb/ft²?

The units can be converted mathematically, but converted values should only be compared as magnetic performance specifications when the original test methods and conditions are sufficiently similar.

Does a larger magnetic sheet hold more?

Increasing effective contact area can increase total holding force under comparable conditions. Large pieces can also introduce uneven contact, curvature, peeling, load-distribution and installation effects, so total performance should be verified on the finished application.

Why does my magnetic sheet feel weaker through vinyl or laminate?

The additional non-magnetic layer creates an effective air gap between the magnet and its target. Flexible multipole magnetic materials can be sensitive to this separation.

Does thicker steel increase magnetic holding force?

Steel thickness can influence magnetic performance because the target forms part of the magnetic circuit. The effect depends on the magnet, steel and geometry, and additional steel thickness eventually may provide little further benefit once the target is no longer the limiting factor.

Can I use pull force to calculate vertical holding capacity?

Not with a universal conversion factor. Vertical holding depends strongly on friction, surface condition, load distribution, vibration and other application variables. Test the assembly in its actual orientation.

What is the best way to compare two flexible magnets?

Compare them using the same sample size, target steel, contact condition, orientation and test procedure. This provides a more meaningful comparison than relying only on datasheet values generated using different methods.

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Safety & Application Reminder

Published magnetic holding-force values should not be treated as guaranteed load capacities for every application.

Where detachment could cause damage, injury or significant loss, test the complete finished assembly under representative conditions and use an appropriate design margin based on the application, uncertainty and consequences of failure.

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Continue Learning About Flexible Magnetic Materials

Start with SSKC-026 — Flexible Magnetic Sheeting Explained for the fundamentals of flexible magnetic material.

Learn how pole configuration affects near-surface magnetic behavior in SSKC-027 — Pole Pitch and Multipole Magnetization.

Understand ferrite composition in SSKC-028 — Strontium vs Barium Ferrite in Flexible Magnets.

Compare common thicknesses in SSKC-031 — 15 mil vs 20 mil vs 30 mil Magnetic Sheeting.

Then use SSKC-032 — How to Choose Flexible Magnetic Sheeting for Your Application to select a construction based on the complete application.

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Need Help Evaluating Flexible Magnet Holding Force?

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