Heat, infrared and the body's response
Micron (µm) and the 12 micron far infrared rating
A micron (µm), properly a micrometre, is a thousandth of a millimetre and a thousand nanometres. So our "12 micron far infrared" and the Red Light sauna's "far-infrared: 12,000 nm" specification are the same number written in two different units.
Also called micrometre, µm, 12 micron, 12,000 nm
The unit conversion, because you will meet both. 1 micron = 1 micrometre (µm) = 1,000 nanometres (nm) = 0.001 millimetres. Multiply microns by 1,000 to get nanometres. 12 µm × 1,000 = 12,000 nm. Our ozone sauna order pages use microns; the Red Light specification uses nanometres, because the same document has to express visible light from 460 nm and near-infrared at 850 nm on the same scale. Nothing differs but the unit.
What the figure describes. A light-emitting diode emits a narrow band, so “850 nm” describes its output closely. A heated surface radiates across a broad, continuous spectrum instead, and where that spectrum peaks depends on the surface’s temperature. So “12 micron” is best read as a band designation — the long-wavelength end of the quoted 12,000 nm span — rather than as the peak output of the emitter. It describes which part of the infrared the heating belongs to, which is a different kind of figure from the precise optical peak that 850 nm describes.
Why it matters here
You will see far infrared quoted in microns on one datasheet and in nanometres on another. Being able to convert between them stops you thinking two products differ when they are describing the same thing.