Gauss Meter Calibration: Hall Probes, Reference Magnets and Zero Offset

Gauss meters (teslameters) measure magnetic flux density. They are used for checking magnetizers and demagnetizers, sorting permanent magnets, verifying residual magnetism after magnetic particle inspection, and mapping fields around motors, MRI suites and particle accelerators. Most use a Hall-effect probe, and the probe is where nearly all the drift happens.

Gauss meter calibration checks the meter and probe together against known magnetic fields and documents the error at each point.

How a gauss meter is calibrated

• Zero offset: the probe is placed in a zero-gauss chamber, a shielded can that blocks the earth’s field and stray fields, and the zero is checked or set.
• Reference magnets: calibrated permanent magnets with a stated field value at the probe position are used to check readings at several field strengths.
• Generated fields: a Helmholtz coil or solenoid driven by a measured current produces a known field, useful for low fields and for AC measurements.

Readings are taken with the probe positioned and oriented exactly as the reference requires. A Hall probe reads the field component perpendicular to its sensing element, so a few degrees of tilt changes the result.

Probes matter more than meters

Hall probes are fragile. Bending the stem, dropping the probe or exposing it to heat can shift its sensitivity, and transverse probes in particular are easy to damage. The meter and probe should be calibrated as a pair, and the certificate should identify the probe by serial number. Many meters store probe calibration data in the probe connector, so swapping probes without recalibration can introduce errors the display never shows.

Units and ranges

Flux density is reported in gauss (G) or tesla (T), where 1 T = 10,000 G and 1 mT = 10 G. Calibration points should cover the fields you actually measure. Residual magnetism checks after magnetic particle inspection often work at a few gauss, while magnet sorting may run to several thousand. State your working range when you send the meter in, so the test points match.

When to recalibrate

Annual calibration is typical. Recalibrate immediately after a probe is dropped, bent or replaced, and whenever readings on a known check magnet change noticeably. A small check magnet kept with the meter makes an easy before-use verification.

Related magnetic and electrical calibration

Gauss meters are often used alongside current probes and clamp meters on the same equipment. Our team can calibrate them on the same visit. See clamp meter calibration and Rogowski coil calibration.

Accreditation and certificates

Gauss meter calibration is on Techmaster’s ANAB ISO/IEC 17025 scope (certificate AC-1736) at our Vista, California lab, so certificates carry the ANAB accreditation symbol along with as-found and as-left data and measurement uncertainty.

Khanh Nguyen

Khanh Nguyen is the Marketing Manager at Techmaster Electronics, a B2B marketing leader covering the test, measurement, and ISO/IEC 17025 accredited calibration industry in the United States.