Magnetic field converter — tesla, gauss, µT and milligauss

How to use the magnetic field converter

1. Enter the reading in Value. The default is 50.
2. Choose its unit in From: tesla, millitesla, microtesla, nanotesla, kilogauss, gauss, milligauss or gamma (γ).
3. Choose the unit you want in To. The default converts microtesla to milligauss.
4. Read the answer and the table of all eight units, plus a note on flux density versus field strength.

What it does and when to use it

Magnetic fields are quoted in SI units (tesla and its fractions) or in the older CGS units (gauss and its fractions), and different fields stick to different habits. MRI scanners are rated in tesla, magnet sellers often use gauss, phone compass apps and geophysics use microtesla or nanotesla, and home EMF meters often show milligauss.

The Earth’s own field is in the tens of microtesla, so a phone magnetometer reading of 50 µT is normal. Use the converter to compare a magnet’s spec with a sensor reading, to read an older physics book, or to put an EMF meter result next to a guideline written in the other system. Because a field is not a current, use the current converter for amperes and the inductance converter for henries.

How it works

Every unit is stored in tesla.

The gauss is defined as exactly 10⁻⁴ T, and NIST lists the same factor. All conversions are powers of ten, so results are exact. They are shown with up to 12 significant figures.

Worked examples

An MRI scanner. 1.5 T = 15,000 gauss, or 15 kilogauss.

An EMF meter reading. 2 mG = 0.2 microtesla (200 nT).

An old textbook value. 0.5 gauss = 50 microtesla, about the size of the Earth’s field in many places.

Limits and tips

• Readings depend on distance. A magnet’s field falls off quickly as you move away, so a gauss rating means little without knowing where it was measured.
• AC and DC fields both use these units, but meters may report peak, average or RMS values. The converter does not change that.
• The tool does not judge whether a field is safe or harmful.