Magnetic Field Strength Conversion Calculator

The oersted measures the H-field (magnetic field intensity), while the gauss measures the B-field (magnetic flux density). In free space (vacuum or air), they are numerically equal in CGS units: $$B(\text{G}) = H(\text{Oe})$$. Inside magnetic materials, the relationship becomes $$B = \mu_r H$$, where $$\mu_r$$ is the relative permeability.

Earth's surface magnetic field ranges from about 25 μT (0.25 G) near the equator to about 65 μT (0.65 G) near the poles, with a global average around 50 μT (0.5 G). This field is generated by convection currents in Earth's liquid iron outer core (the geodynamo).

Clinical MRI machines typically use fields of 1.5 T or 3 T (15,000 or 30,000 G). Research MRI systems can reach 7 T or even 11.7 T. These powerful fields align hydrogen nuclei in body tissues, enabling detailed medical imaging.

Kilogauss (kG) provides convenient numbers for strong magnets: a 1 T magnet is 10 kG, avoiding the large numbers that gauss would produce (10,000 G). It is commonly used in specifications for permanent magnets, electromagnets, and particle accelerator dipoles.

In vacuum or air, $$B = \mu_0 H$$ where $$\mu_0 = 4\pi \times 10^{-7}$$ T·m/A. In CGS, this simplifies to $$B(\text{G}) = H(\text{Oe})$$ numerically. Inside magnetic materials, you need the material's permeability: $$B = \mu_0 \mu_r H$$. This calculator assumes free-space conditions for the Oe conversion.