Date
18 August 2026
Category
Author
Conal McLaughlin
The word “strength” is used for several different magnet measurements. A supplier may quote pull force in newtons, a sensor engineer may ask for surface Gauss, and a material data sheet may list remanence (Br) and maximum energy product (BHmax). These values are related, but they do not describe the same thing.
That distinction matters when comparing magnets. A higher Br or BHmax does not automatically give a finished component a higher surface reading or greater holding force. Geometry, magnetisation direction, air gap, steel thickness, temperature and the test method can all change the result.
Key takeaway: Pull force describes force under stated test conditions. Surface Gauss describes flux density at a stated location. Br and BHmax describe the magnet material. None of these values should be substituted for another without considering the complete magnet and application.
The most useful measurement depends on whether you are comparing a material, checking the field from a finished magnet or testing force in a defined assembly.
The force required to separate a magnet from a specified target in a specified direction and test arrangement.
A magnetic flux-density reading taken at a defined position on or near a finished magnet.
The residual magnetic flux density of a saturated magnetic material at zero applied magnetising field under defined measurement conditions.
The maximum product of flux density and field strength on the material’s demagnetisation curve.
No. Br and BHmax are obtained from the magnetic material’s demagnetisation behaviour. Surface Gauss and pull force are outputs from a finished magnet or magnetic circuit. The material properties influence those outputs, but they do not determine them on their own.
A useful way to view the relationship is to move from material capability towards application performance:
Describe the magnetic material and its energy capability.
Shape, dimensions and magnetisation determine where the usable field appears.
Measures flux density at one stated location around the finished component.
Measures separation force within a particular contact and magnetic-circuit arrangement.
The sequence is not a universal calculation. It shows why a material value cannot be treated as a guaranteed finished-part result. The same grade can produce very different field and force values when its dimensions or surrounding magnetic circuit change.
Pull force is the force required to separate a magnet from a target, normally measured perpendicular to the main pole face. It is usually quoted in newtons or kilogram-force. A meaningful value must be tied to a test arrangement.
Typical catalogue or calculated pull-force values assume favourable conditions such as clean, flat, direct contact with sufficiently thick, non-saturated steel. Real applications may include paint, coatings, adhesive, roughness, curvature or an intentional air gap. Each of these can reduce the measured force.
For an idealised, approximately uniform field at an interface, force is related to the square of flux density and the effective pole area. A real magnet-to-steel circuit is not perfectly uniform, so this relationship explains the trend rather than replacing a validated model or physical test.
Kilogram-force is another way of expressing force; it is not the mass a magnet can safely hold. One kilogram-force equals approximately 9.80665 newtons. Neither value includes a safety factor or accounts for shock, vibration, shear loading or installation variation.
For an indicative estimate under defined ideal conditions, use the GUK Magnetic Pull Force Calculator. Final performance should be tested in the intended configuration.
Surface Gauss is a flux-density reading taken on or close to a magnet’s surface. Despite the name, it is not necessarily one fixed value for the entire magnet. The reading changes across the pole face and can fall rapidly as the probe moves away from the surface.
The highest reading may occur near an edge rather than at the centre, depending on the geometry and magnetisation pattern. A transverse probe and an axial probe can also measure different field components. Quoting “surface Gauss” without the location, distance and probe orientation can therefore create ambiguity.
Remanence, written as Br, is the residual magnetic induction of a magnetic material after it has been saturated and the applied magnetising field has been reduced to zero under defined measurement conditions. It is normally listed in tesla, millitesla or kilogauss on a material data sheet.
Br is useful for comparing grades within a material family and is an important input when estimating the performance of a finished magnet. However, it is not a surface measurement. A neodymium grade with a Br value around 1.3 T should not be expected to give a 1.3 T reading at every point on the finished magnet’s surface.
The finished field depends on the magnet’s aspect ratio, magnetic length, pole area, magnetisation direction, temperature and surrounding circuit. This is why the GUK pull-force calculator uses Br together with the magnet geometry rather than treating Br as the output.
A high Br indicates strong residual induction, but it does not describe resistance to demagnetisation. Coercivity values such as HcB and HcJ provide that information. An application exposed to elevated temperatures or opposing fields may require a grade with greater intrinsic coercivity even if another grade has a higher room-temperature Br.
For more detail on Br, coercivity and temperature behaviour, see Understanding Magnetic Properties.
Maximum energy product, or BHmax, is the maximum value of magnetic flux density multiplied by magnetic field strength on the material’s demagnetisation curve. It is expressed in megagauss-oersteds (MGOe) or kilojoules per cubic metre (kJ/m³).
BHmax is best understood as an indicator of magnetic energy density. A material with a higher BHmax can generally provide the required magnetic output from a smaller volume, assuming the magnet and magnetic circuit are designed appropriately.
Neodymium grade numbers broadly relate to BHmax in MGOe. For example, an N42 grade has a specified BHmax range around the low-forties MGOe, depending on the supplier’s data sheet. The number does not state pull force, surface Gauss or maximum working temperature.
Two magnets made from the same production batch can have essentially the same material properties. If their thickness, pole area or magnetisation direction differs, their surface field and pull force can be substantially different.
A small high-grade neodymium magnet does not automatically outperform a much larger lower-grade magnet. The higher grade provides greater energy density, but the finished result also depends on volume and geometry.
The same component can produce different Gauss and pull-force results when the measurement distance, steel target, surface condition, temperature or test fixture changes.
This is also why supplier figures should only be compared when the underlying conditions match. A pull-force value against thick ground steel at zero gap is not equivalent to a value measured through paint against a thin bracket. Likewise, a peak edge Gauss reading cannot be compared directly with a centre-face reading taken one millimetre away.
Start with the function the magnet must perform. The most useful acceptance criterion is the one that represents the real application and can be measured consistently.
Before deciding that one magnet is stronger than another, check whether you are comparing the same type of information.
Estimate ideal pull force for supported disc, block and ring geometries using a selected grade or manual Br input.
Estimate pull force → Technical toolMagnetic Unit ConverterConvert flux density, field strength and maximum energy product between the units used on data sheets and RFQs.
Convert magnetic units →A request such as “strong magnet” or “high Gauss” does not provide enough information to confirm suitability. Where possible, connect the magnetic requirement to the geometry, measurement position and intended function.
When an established application already has a validated test method, including that method with the RFQ is usually more useful than replacing it with a generic material value.
GUK Magnetics supplies neodymium, samarium cobalt, ferrite and AlNiCo magnets to customer drawings and specifications. We can review material properties, geometry, magnetisation, operating conditions and target measurements to advise on practical magnet or assembly supply options.
Our role is to advise on magnet selection and manufacturability rather than design the customer’s complete product or magnetic system. Final application performance should be validated using the intended components, assembly and operating conditions.
Send your drawing, material requirement, magnetisation direction, target field or force, operating conditions and anticipated quantities. We can review the specification and advise on practical supply options.
Discuss Your RequirementsNo. Br is a property measured from the magnetic material under defined conditions. Surface Gauss is a flux-density reading taken at a particular location on or near a finished magnet. Geometry and measurement position mean the surface reading will not simply equal the Br value.
Not necessarily. Pull force depends on the field across the effective contact area and the complete magnetic circuit. A single Gauss reading does not describe the whole field distribution, pole area, air gap or steel target.
N52 has a higher maximum energy product than N42, but complete magnets can only be compared after considering their geometry, volume, magnetisation, temperature and application. A larger N42 magnet may produce more pull force than a smaller N52 magnet.
Br can be used as an input within a suitable geometry-dependent model, but it is not enough on its own. The magnet shape, dimensions, magnetisation direction, contact area, air gap and target material must also be considered.
Both are units of magnetic flux density. One tesla equals 10,000 Gauss, and one millitesla equals 10 Gauss.
Both are units used for maximum energy product. One MGOe is approximately 7.958 kJ/m³. The GUK Magnetic Unit Converter can translate between them.
Use the value that represents the functional requirement and can be tested consistently. That may be pull force in a defined fixture, flux density at a sensor position or material-property ranges from an approved data sheet. Always include the associated conditions and tolerance.
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