Whether you're in physics class or need it for an upcoming project, calculating magnetic field strength with accuracy is a must. And, there are some important variables that you should be made aware of.

    Here's everything you need to know about magnetic field strength, how it's applied, and how it's measured.

    For easy and accurate conversions between 4 standard units, try our free magnetic field strength calculator.


    What is magnetic field strength defined as?

    Magnetic field strength is defined as the current density and displacement current, independent from other physical properties surrounding the medium.

    It's primarily known as one of the ways that magnetic intensity can be measured.

    So if we're speaking in technical terms, the magnetic field is going to be referred to as the section of the magnet where moving electric charges are found.

    These charges can be created either through moving charges or variable fields.

    They can either be microscopic or macroscopic and some are dependent on the spin and orbital motion of their electrons in order to produce the magnetic effect.

    How is it measured?

    Just like anything else, it's important to know how magnetic field strength is measured.

    There are actually two different ways to classify magnetic intensity:

    • Magnetic field strength (denoted by H) is written in amperes per meter (A/m) or,
    • Magnetic flux density (denoted by B) is written in Newton meters per ampere (Nm/A)

    So, how is it different from magnetic flux density?

    The correlation between magnetic field strength (H) and magnetic flux density (B) is defined as:

    H = B รท ๐œ‡


    • The unit ๐œ‡ is used for the magnetic permeability of space, which is a constant value.
    • The B variable stands for magnetic flux density.


    The main differences in measuring magnetic field strength are whether or not it's defined by flux density:

    • If it's defined by flux density, Gauss (G) and Tesla (T) are used.
    • If it's defined by it's coercive force, Oersted is used.

    How do you convert between similar units?

    Here is a basic chart as a point of reference:

    Magnetic Field Strength Conversion Table

    1 Gauss (G) = .01 mT = 1 Oe = 0.07977 kA/m
    1 milli Tesla (mT) = 10 G = 10 Oe = 0.7977 kA/m
    1 Oersted (Oe) = 1 G = .01 mT = 0.07977 kA/m
    1 kilo Ampere per meter (kA/m) = 12.54 G =1.254 mT = 12.54 Oe

    Sometimes, the math can get tough. To make life easier, you can use our magnetic field strength converter.

    Select your starting unit and the unit you want to convert to, then simply add the amount in the line above. Say goodbye to pesky equations, and hello to effortless conversions!

    What is the magnetic field strength of common objects?

    If you're new to the magnetic field strength world - this all might seem as though it's not necessarily relative.

    Fortunately, we've put together a chart that will help you relate magnetic field strength and objects you actually know.

    • 0.5 Oersted - The earth's gravitational magnetic field, surface level
    • 100 Oersted - The magnets on your refrigerator
    • 1,100 Oersted - Magnetic Rubber
    • 3,700 Oersted - Ceramic Magnets for construction
    • 11,000 Oersted - Samarium Cobalt magnet
    • 12,500 Oersted - Alnico level 5 magnet
    • 13,000 Oersted - Neodymium magnets

    Which factors influence magnetic field strength?

    In order to understand the 101 on Magnetic Field Strength, it's important that you understand the various aspects that are associated with it:

    1. Maximum Energy Product

    One of the most important variables you are going to come across when measuring magnetic field strength is maximum energy product.

    This is going to be one of the key indicators of the magnet's strength. Our point of reference?

    The higher the maximum energy product number, the stronger the magnetic field strength

    2. Remanence

    Just like it sounds, remanence is going to be what's left over after removing the external piece that was applied to make it magnetic.

    When it's all said and done, the remanence will tell you how strong the magnet's resistance is.

    3. Coercivity

    Coercivity is going to be the work required to reduce magnetization to zero. The equation calls for measuring the resistance to demagnetization.

    These are going to be measured in Oesterds. (Oe)

    4. Pull Strength

    A magnet's pull strength is going to be pinnacle when trying to determine how much weight it can hold.

    The pull strength is most important to manufacturers whose objective is to provide suppliers with a reliable product that won't give out on their customers.

    Usually measured in kilograms, a magnet's pull strength is going to generally be the highest hold power a magnet can contain.

    5. Open Circuit Flux Density

    Remember how we stated that flux density was measured in Newton-meters (N/m)?

    These flux densities are usually measured using Gauss meters and hall probes.

    As a point of reference, open circuit flux densities never really go past 6,000 Gauss. Magnetic flux density is known for decreases when the distance between the magnet and metal is increased.

    6. Pull Gap Curve

    If you ever want a visual representation of magnetic field strength power - a pull gap curve is going to be extremely useful.

    Because it measures the point where the pull (kg) and air gap (mm) meet, this chart makes it easy to determine the power of a magnet when it comes in contact with a piece of metal.

    Fun Fact:

    If you've ever played with the magnets on your refrigerator, that force you feel when the magnet is close enough to the metal, but not touching is going to be what's measured in the pull gap curve.

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