Magnetic Field Intensity Units

The International System (SI) unit of field intensity for magnetic fields is Tesla (T). One tesla (1 T) is defined as the field intensity generating one newton of force per ampere of current per meter of conductor:

T = N · A-1 · m-1 = kg · s-2 · A-1

Certain other non-SI units, like Gauss (G), are still occasionally used. Some are important for the interpretation of older scientific texts but their use is not encouraged. One gauss (1 G) is the field intensity generating 0.1 dyne of force per ampere of current per centimeter of conductor. Therefore, the difference between tesla and gauss remains in the units used to define them. Thus, one tesla equals 10000 gauss (1 T = 10000 G), or one gauss equals 0.0001 tesla (1 G = 0.0001 T). Other units commonly used are microtesla (µT) and miligauss (mG). The next table shows the conversion factors from one unit to another:

Tesla (T) Microtesla (µT) Gauss (G) Miligauss (mG)
1 1000000 10000 10000000
0.000001 1 1000 10
0.0001 0.001 1 1000
0.0000001 0.1 0.001 1

A magnetic field of one tesla is quite strong. That is why magnetic fields are usually expressed in microtesla (µT). Typical values of field intensity for some magnetic fields are:

Field µT
Strongest fields available in laboratories 20 000 000
Earth's magnetic field intensity, at its surface 50
Domestic electrical appliances 0.02 to 7
Interstellar magnetic field 0.000 000 3

The International Bureau of Weights and Measures (BIPM) provides further information on the International System of Units (SI) at  and on prefixes of the International System of Units (SI) at 

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