Infrared saunas are sold on wavelengths: far, near, mid, and “full spectrum.” It’s the most technical-sounding part of any spec sheet and one of the hardest to compare between brands.
This article explains what “full spectrum” means and how to compare it fairly. For the rest of the buying decisions, start with the infrared sauna buying guide.
Short answer: “full spectrum” means a cabin mixes far-infrared panels with near- and mid-infrared emitters. The labels aren’t used consistently, so compare where each heater sits and how many watts it draws.
The official definitions
In optics, the ISO 20473 standard splits infrared into three bands:
| Band | ISO 20473 range |
|---|---|
| Near-infrared | 0.78–3 µm |
| Mid-infrared | 3–50 µm |
| Far-infrared | 50 µm–1 mm |
Sauna marketing uses the same three words, but brands rarely publish wavelengths that line up with those ranges. Treat “near,” “mid,” and “far” on a sauna page as brand descriptions, not measured bands.
What full spectrum looks like in a real cabin
Here’s what the spec sheet won’t tell you in one line: full-spectrum cabins differ in where the extra heaters go.
| Cabin | Heater layout (per listing) |
|---|---|
| Clearlight Sanctuary 2 | Two 500W full-spectrum emitters on the front wall; far-infrared on the back, sides, and floor |
| Finnmark FD-3 | Long-wave carbon panels plus short-wave Spectrum Plus panels, 3,150W total |
| Sunlighten Signature II | Far-infrared SoloCarbon heaters only |
| Dynamic Barcelona | Six far-infrared carbon panels only |
How to compare
- Count the heaters and note where each one sits.
- Add up the wattage. More watts usually means faster heat-up and a bigger circuit.
- Check the circuit. The FD-3’s 3,150W needs a 240V/15A circuit; the Sanctuary 2 runs on 120V/20A.
- Read the warranty on each heater type, since emitters and panels can be covered differently.
Run the numbers on the ISO bands
The table uses micrometers. Product pages use nanometers. One micrometer is 1,000 nanometers, so the ISO near-infrared band of 0.78 to 3 µm is 780 to 3,000 nm.
That helps with a common mix-up. Red light therapy panels list wavelengths such as 660nm and 850nm. By the ISO ranges, 850nm is near-infrared and 660nm is visible red light. Those panels are LED devices sold for light, not heat. A sauna’s “near-infrared” heater and a panel’s “near-infrared” LED share a word and are different products.
How much of the cabin is “full spectrum”?
In the Clearlight Sanctuary 2, the full-spectrum part is two 500W emitters on the front wall, 1,000W in all. The far-infrared heaters on the back, sides, and floor do the rest. Our data doesn’t give the cabin’s total wattage, so we can’t say what share that is. Ask the dealer.
The question is worth asking of any full-spectrum cabin: how many watts come from the near- and mid-infrared emitters, and how many from the far-infrared panels? If the answer is a small fraction, you are buying a far-infrared cabin with an accent.
What it changes in practice
Temperature. The Finnmark FD-3, which adds short-wave panels, lists a maximum of 170°F. The far-infrared Dynamic Andora lists 140°F.
Circuit. The FD-3’s 3,150W needs 240V. The Sanctuary 2 needs a 20A outlet. The far-infrared Barcelona runs on a 15A outlet.
Price. The FD-3 lists at $6,495 and the Barcelona at $3,499. That $2,996 gap isn’t only the heaters, since the FD-3 seats four and the Barcelona one or two. The Sanctuary 2 has no published price.
Three questions for the seller
- Which heaters are near-, mid-, and far-infrared, and how many watts is each?
- What wavelength range does each emitter produce, with a test report?
- Is each heater type covered by the same warranty?
A seller who can answer the first has more to offer than the label.
Is it worth paying for?
You get more variety with full spectrum: near-infrared emitters feel more intense on the skin facing them. You give up simplicity and usually some money, and the health claims attached to specific wavelengths go beyond what the evidence clearly supports. Cleveland Clinic notes that detox research, for example, is “still in its infancy.”
My rule of thumb: buy full spectrum for the experience, not for promised health outcomes. If you just want gentle, dry heat, a far-infrared cabin does the job.
To see a full-spectrum cabin next to far-infrared alternatives, see our infrared sauna comparison.
Bottom line: “full spectrum” is a heater layout, not a guarantee. Compare the layout, the watts, and the warranty.
Sources
- RP Photonics, “Infrared Light” (ISO 20473 spectral bands), accessed October 2, 2026: rp-photonics.com
- Cleveland Clinic, “Why Infrared Saunas Are ‘Cooler’ Than Traditional Saunas,” April 14, 2022: health.clevelandclinic.org
- Heater layouts and power: Clearlight, Finnmark, Sunlighten, and Dynamic Saunas listings, checked October 1, 2026
- Finnmark FD-3, Dynamic Andora, and Dynamic Barcelona listings (maximum temperature, price), checked September–October 2026