microtesla

Microtesla (symbol μT) is the SI unit of magnetic flux density equal to one millionth of a tesla (1 μT = 1×10^-6 T). It is commonly used to quantify magnetic fields of environmental, geological, or engineering origin that are weaker than those typically encountered near electrical equipment.

In relation to other units, 1 tesla equals 10,000 gauss, so 1 μT equals 0.01 gauss, or 10 milligauss. The Earth's magnetic field at the surface generally ranges from about 25 to 65 μT, depending on location and time; it is stronger at higher latitudes, weaker near the equator, and affected by solar activity and local magnetic anomalies.

Measurements are made with magnetometers such as fluxgate, proton-precession, optically pumped, or Hall-effect sensors. For high-precision field surveys, vector magnetometers can resolve both intensity and direction, while portable devices enable fieldwork. In laboratory settings, more sensitive instruments like SQUID magnetometers can detect far smaller fields in the pico- to nano-tesla range, but μT-level sensors are common for field measurements.

Common applications include geophysical and archaeological magnetic surveys, mineral exploration, environmental monitoring, and calibration of instrumentation. The μT provides a practical scale for describing ambient magnetic fields in many natural and urban environments, bridging the gap between strong artificial fields and the far weaker signals detected in specialized research contexts.