Magnetic flux density
The quantity an ELF gaussmeter reports, expressed in milligauss or microtesla, used to assess wiring, transformers and power lines. 1 µT = 10 mG.
Symbol BSI unit T
Last verified 12 August 2026.
Also searched as: B field, magnetic field, gauss, tesla
- Symbol
- B
- SI unit
- T
- Units in use
- T, mT, µT, nT, G, mG
What it measures
Magnetic component of a low-frequency field. Passes through walls and almost all shielding materials, so mitigation is by distance or by fixing the current imbalance that creates it.
Units
Multiplier to the SI unit (T).
- T (tesla)
- 1 T = 1 T
- mT (millitesla)
- 1 mT = 0.001 T
- µT (microtesla)
- 1 µT = 1 × 10^-6 T
- nT (nanotesla)
- 1 nT = 1 × 10^-9 T
- G (gauss)
- 1 G = 0.0001 T
- mG (milligauss)
- 1 mG = 1 × 10^-7 T
Relationships to other quantities
- H (A/m) = B (µT) / 1.25663706
- Magnetic field strength H relates to flux density B by the permeability of free space, µ₀ = 4π × 10⁻⁷ H/m. 1 A/m ≈ 1.2566 µT in air.
Related records
- Building Biology SBM-2024 AC magnetic field bands
Sleeping-area grades at 50/60 Hz: below 0.2 mG no anomaly, 0.2–1 mG weak, 1–5 mG strong, above 5 mG extreme.
Exposure limits
- ICNIRP 2010 general public magnetic field reference level at 50/60 Hz
200 µT (2000 mG) for the public and 1000 µT occupational — five orders of magnitude above typical household background.
Exposure limits
Sources
- nist-si The International System of Units (SI), NIST Special Publication 330 — National Institute of Standards and Technology. government, link checked 2026-08-12.
- sbm-2024 Building Biology Evaluation Guidelines for Sleeping Areas (SBM-2024) — Institut für Baubiologie + Nachhaltigkeit (IBN), 2024. ngo, link checked 2026-08-12.
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