Orders of magnitude (magnetic field)

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This page lists examples of magnetic induction B in teslas and gauss produced by various sources, grouped by orders of magnitude.


  • Traditionally, magnetizing field H, is measured in amperes per meter.
  • Magnetic induction B (also known as magnetic flux density) has the SI unit tesla [T or Wb/m2].[1]
  • One tesla is equal to 104 gauss.
  • Magnetic field drops off as the cube of the distance from a dipole source.

Orders of Magnitude[edit]

These examples attempt to make the measuring point clear, usually the surface of the item mentioned.

List of orders of magnitude for magnetic fields
Factor (tesla) SI prefix Value (SI units) Value (CGS units) Item
10−18 attotesla 5 aT 50 fG SQUID magnetometers on Gravity Probe B gyroscopes measure fields at this level over several days of averaged measurements[2]
10−15 femtotesla 2 fT 20 pG SQUID magnetometers on Gravity Probe B gyros measure fields at this level in about one second
10−12 picotesla 100 fT to 1 pT 1 nG to 10 nG Human brain magnetic field
10−11 10 pT 100 nG In September 2006, NASA found "potholes" in the magnetic field in the heliosheath around our solar system that are 10 picoteslas as reported by Voyager 1[3]
10−9 nanotesla 100 pT to 10 nT 1 µG to 100 µG Magnetic field strength in the heliosphere
10−6 microtesla 24 µT 240 mG Strength of magnetic tape near tape head
10−5   31 µT 310 mG Strength of Earth's magnetic field at 0° latitude (on the equator)
58 µT 580 mG Strength of Earth's magnetic field at 50° latitude
10−3 millitesla 0.5 mT 5 G The suggested exposure limit for cardiac pacemakers by American Conference of Governmental Industrial Hygienists (ACGIH)
5 mT 50 G The strength of a typical refrigerator magnet[4]
10−1   0.15 T 1.5 kG The magnetic field strength of a sunspot
100 tesla 1 T to 2.4 T 10 kG to 24 kG Coil gap of a typical loudspeaker magnet.[5]
1 T to 2 T 10 kG to 20 kG Inside the core of a modern 60 Hz power transformer[6][7]
1.25 T 12.5 kG Strength of a modern neodymium–iron–boron (Nd2Fe14B) rare earth magnet. A coin-sized neodymium magnet can lift more than 9 kg, erase credit cards.[8]
1.5 T to 3 T 15 kG to 30 kG Strength of medical magnetic resonance imaging systems in practice, experimentally up to 11.7 T[9][10][11]
9.4 T 94 kG Modern high resolution research magnetic resonance imaging system; field strength of a 400 MHz NMR spectrometer
101   11.7 T 117 kG Field strength of a 500 MHz NMR spectrometer
16 T 160 kG Strength used to levitate a frog[12]
23.5 T 235 kG Field strength of a 1 GHz NMR spectrometer[13]
36.2 T 362 kG Strongest continuous magnetic field produced by non-superconductive resistive magnet.[14]
45 T 450 kG Strongest continuous magnetic field yet produced in a laboratory (Florida State University's National High Magnetic Field Laboratory in Tallahassee, USA).[15]
102   100 T 1 MG Strongest pulsed non-destructive magnetic field produced in a laboratory, Pulsed Field Facility at National High Magnetic Field Laboratory's, Los Alamos National Laboratory, Los Alamos, NM, USA).[16]
103 kilotesla 1 kT 100 MG Strongest (pulsed) magnetic field ever obtained in a laboratory (Z machine, Sandia National Laboratories in Albuquerque, New Mexico)[17]
106 megatesla 1 MT to 100 MT 10 GG to 1 TG Strength of a neutron star
108 - 1011 gigatesla 100 MT to 100 GT 1 TG to 1 PG Strength of a magnetar
1053 N/A 2×1029 YT 2×1033 YG Planck magnetic field strength


  1. ^ "Bureau International des Poids et Mesures, The International System of Units (SI), 8th edition 2006" (PDF). bipm.org. 2012-10-01. Retrieved 2013-05-26. 
  2. ^ [1] Gravity Probe B
  3. ^ "Surprises from the Edge of the Solar System". NASA. 2006-09-21. 
  4. ^ "Information on MRI Technique". Nevus Network. Retrieved 2014-01-28. 
  5. ^ Elliot, Rod. "Power Handling Vs. Efficiency". Retrieved 2008-02-17. 
  6. ^ "Inductors and transformers" (PDF). eece.ksu.edu. 2003-08-12. Archived from the original (PDF) on September 8, 2008. Retrieved 2013-05-26. A modern well-designed 60 Hz power transformer will probably have a magnetic flux density between 1 and 2 T inside the core. 
  7. ^ "Trafo-Bestimmung 3von3". radiomuseum.org. 2009-07-11. Retrieved 2013-06-01. 
  8. ^ The Tesla Radio Conspiracy
  9. ^ Savage, Niel. "The World's Most Powerful MRI Takes Shape". 
  10. ^ Smith, Hans-Jørgen. "Magnetic resonance imaging". Medcyclopaedia Textbook of Radiology. GE Healthcare. Retrieved 2007-03-26. [dead link]
  11. ^ Orenstein, Beth W. (2006-02-16). "Ultra High-Field MRI — The Pull of Big Magnets". Radiology Today. 7 (3). p. 10. Archived from the original on March 15, 2008. Retrieved 2008-07-10. 
  12. ^ "Frog defies gravity". 
  13. ^ "23.5 Tesla Standard-Bore, Persistent Superconducting Magnet". 
  14. ^ "Mag Lab Reclaims World Record for Highest Field Resistive Magnet". 
  15. ^ "World's Most Powerful Magnet Tested Ushers in New Era for Steady High Field Research". National High Magnetic Field Laboratory. 
  16. ^ "Pulsed Field Facility - MagLab". Pulsed Field Facility. 
  17. ^ "Z machine makes progress toward nuclear fusion". October 10, 2014. Retrieved August 10, 2016.