The tesla is the SI unit of magnetic flux density named after Nikola Tesla. Its symbol is T, and it measures the strength of a magnetic field, also called magnetic B-field.
The tesla is a derived SI unit. One tesla equals one weber per square metre, written 1 T = 1 Wb/m². It can also be expressed as one newton per ampere-metre, linking magnetic force to electric current and the length of a conductor.
The unit was formally adopted in 1960 by the General Conference on Weights and Measures. It honors Tesla, whose work on alternating-current systems, induction motors, and rotating magnetic fields helped shape modern electrical engineering.
A common mix-up is the gauss, another unit of magnetic flux density from the centimetre-gram-second system. One tesla equals 10,000 gauss. Everyday magnetic fields are usually much smaller than one tesla, while medical MRI scanners commonly operate at around 1.5 to 3 teslas.