Magnetic Field Converter

Magnetic field strength, more precisely the magnetic flux density, measures how concentrated a magnetic field is at a point. The SI unit is the tesla (T). It’s the partner of magnetic flux: flux (in webers) is the total field passing through an area, while the tesla tells you how tightly that field is packed.

Metric prefixes:

• 1 T = 1,000 mT (millitesla)
• 1 T = 1,000,000 µT (microtesla)

CGS unit (gauss):

• 1 T = 10,000 gauss (G)
• 1 kG = 1,000 G = 0.1 T

Fields you can picture:

• Earth’s field at the surface: 25–65 µT (0.25–0.65 G)
• A fridge magnet: about 5 mT (50 G)
• A hospital MRI scanner: 1.5–3 T

The gauss refuses to retire because a tesla is enormous for everyday magnets. Quoting Earth’s field as “half a gauss” feels more natural than “50 microtesla,” so geophysics and magnet datasheets still reach for it.

The MRI number puts the scale in perspective. A 3 T scanner runs about 50,000 times stronger than Earth’s field, which is exactly why a loose wrench becomes a projectile in that room. Field strength also drops off fast with distance, roughly with the cube of distance for a small magnet, so a magnet that grabs hard on contact does almost nothing an inch away.