Magnetic Flux Density Converter
Convert magnetic flux density between tesla, millitesla, microtesla, nanotesla, gauss, and kilogauss. Enter a value, then choose the From unit and To unit.
Convert Magnetic Flux Density Between Units
Magnetic Flux Density Formula
Where:
- \(B_{\mathrm{from}}\) — the entered magnetic flux density
- \(B_{\mathrm{to}}\) — the converted magnetic flux density
- \(f_{\mathrm{from}}\) — tesla per unit of the selected From unit
- \(f_{\mathrm{to}}\) — tesla per unit of the selected To unit
The converter first expresses the entered value in tesla, then divides by the tesla equivalent of the target unit. The factors are listed in the reference table below.
Magnetic Flux Density – Calculation Example
Example: With the default settings, convert 0.01 tesla to gauss.
Because 1 T equals 10,000 G, multiply the value in tesla by 10,000:
\[ 0.01\,\mathrm{T}\times 10^{4}\,\frac{\mathrm{G}}{\mathrm{T}}=100\,\mathrm{G} \]
Result: 0.01 T = 100 G.
How to use the calculator
- Enter a nonnegative number in Magnetic flux density value. The default is 0.01.
- Choose the unit of that number under From unit. The default is Tesla (T).
- Choose the unit you need under To unit. The default is Gauss (G).
- Read Converted Magnetic Flux Density, which displays the converted number and its unit symbol.
You can choose the same unit in both menus to leave the numerical value unchanged. For a conversion in the opposite direction, swap the two unit selections and enter the value you want to convert.
What magnetic flux density means
Magnetic flux density, usually written \(B\), describes the magnetic field in terms of the flux passing through an area. Its SI unit is the tesla (T), equal to one weber per square meter (Wb/m²). Flux density is used when describing fields around magnets and coils, and in equipment such as electric motors, transformers, and MRI systems. Converting its units changes only how a field value is expressed; it does not change the field itself.
Tesla and its metric submultiples are convenient for different field magnitudes: millitesla (mT), microtesla (µT), and nanotesla (nT) represent successively smaller units. Gauss (G) and kilogauss (kG) are also used in magnetic-field specifications and older references. For example, 0.01 T, 10 mT, and 100 G all describe the same flux density. Selecting a suitable unit can make results easier to read and compare.
Magnetic flux density is related to, but different from, magnetic flux. Flux describes a total through a surface, while flux density describes a field at a point or over a region. It is also distinct from magnetic field strength \(H\), which is measured in amperes per meter. The relationship between \(B\) and \(H\) depends on the medium; permeability is relevant when working with that relationship. This page converts units of \(B\); it does not calculate \(B\) from flux, current, or material properties.
Conversion factors
The calculator uses tesla as its common reference. Multiply a value by the factor in the right-hand column to express it in tesla; divide a value in tesla by that factor to express it in the listed unit.
| Unit | Symbol | Tesla per unit |
|---|---|---|
| Tesla | T | 1 |
| Millitesla | mT | 0.001 |
| Microtesla | µT | 0.000001 |
| Nanotesla | nT | 0.000000001 |
| Gauss | G | 0.0001 |
| Kilogauss | kG | 0.1 |
In particular, 1 T = 10,000 G and 1 G = 100 µT. Also, 1 kG = 1,000 G = 0.1 T. These equalities are useful checks when moving between SI units and gauss-based measurements.
Assumptions and practical tips
This is a unit converter, not a model of a magnetic field. It assumes the entered number already represents magnetic flux density and applies fixed conversion factors. Weber per square meter is equivalent to tesla, but Wb/m² is not a separate menu option. If a source gives a value in Wb/m², select T as the From unit.
The input accepts nonnegative values. A negative value can indicate direction along a chosen axis, but that sign cannot be entered here; converting a magnitude does not describe the field’s direction. Keep any direction information separately when reporting a measurement.
The displayed result is rounded to ten decimal places. Very small results in a large unit, such as an extremely small field expressed in tesla, may therefore display as zero. Choose a smaller target unit, such as nT, to show more of the value. Conversion also cannot add precision to the original measurement: report only as many significant digits as its source supports.
Frequently Asked Questions
How do I convert microtesla to gauss by hand?
Divide the value in microtesla by 100, because 100 µT equals 1 G. For example, 250 µT is 2.5 G. To convert back, multiply the gauss value by 100. Write down the starting unit before calculating: confusing microtesla with millitesla changes the result by a factor of 1,000.
What is a typical magnetic flux density for Earth’s magnetic field?
Earth’s magnetic field is typically about 25–65 µT at the surface, or 0.25–0.65 G. The value varies by location and changes gradually over time. A phone or handheld meter may also detect nearby magnets, electrical equipment, and metal objects, so a local reading need not match a published value for your area.
How can I calculate magnetic flux density from magnetic flux?
For a uniform field passing straight through a flat surface, divide magnetic flux by area: \(B=\Phi/A\). A flux of 0.02 Wb through 0.01 m² gives 2 T. If the field meets the surface at an angle, use \(\Phi=BA\cos\theta\), where \(\theta\) is measured from the surface normal. These formulas require care when the field varies across the area.
How are magnetic flux density \(B\) and magnetic field strength \(H\) related?
In a linear, isotropic material, \(B=\mu H\), where \(\mu\) is the material’s permeability. In vacuum, \(\mu=\mu_0\). This is not a universal fixed-factor unit conversion: in some materials, permeability changes with field strength, and magnetized materials can retain a field after an applied field is removed. You need information about the medium to calculate one quantity from the other.
Should I convert each magnetometer axis or the total field?
Convert whichever quantity you intend to report. A three-axis magnetometer gives directional components \(B_x\), \(B_y\), and \(B_z\); each component can be converted separately. If you need the total field magnitude, first calculate \(\sqrt{B_x^2+B_y^2+B_z^2}\), then convert it. Do not add the three readings directly, because their signs and directions matter.
Why does a magnet’s measured flux density change with distance?
The magnetic field is not equally strong everywhere around a magnet, so moving the probe changes its reading. Probe orientation matters too, especially when a sensor measures only one directional component. There is no single distance-conversion factor that works for every magnet; its shape, size, and surroundings affect the field. Record the measurement position when comparing specifications or readings.
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