If you've shopped for a red light device, you've seen two numbers everywhere: 660nm and 850nm. They describe the wavelength of the light, measured in nanometers. Here's what that actually means, without the hype.
What is 660nm red light?
660nm sits in the visible red part of the spectrum. It's the deep red glow you can actually see when a device is switched on. Because it's visible, 660nm is the wavelength most people picture when they think of "red light therapy." It interacts mostly with the surface layers of the skin.
What is 850nm near-infrared light?
850nm is just past what the human eye can see, in the near-infrared (NIR) range. You won't see much glow from 850nm LEDs on their own, but the light is still there. Near-infrared wavelengths are longer than visible red and are generally described as reaching beyond the surface compared with visible red light.
Why do good devices use both?
Many premium red light panels combine both wavelengths so you get a more complete session in one go. That's why every LED in LumaBelt is a 3-in-1 diode that pairs 660nm red with 850nm near-infrared. You can run them together, separately, or in a pulse mode.
How to tell if a device is legit
- Check the wavelengths. Look for specific numbers (like 660nm and 850nm), not vague terms like "therapeutic light."
- Look for modes and timers. An auto-off timer makes consistent, comfortable sessions easy.
- Read the guarantee. A long return window shows a brand stands behind its product.
- Be wary of miracle claims. Red light is a popular wellness ritual, not a cure-all. Honest brands say so.
The bottom line
660nm is the visible red glow; 850nm is invisible near-infrared. Using both gives you the same wavelength combination found in premium panels, in a format you can wear on the couch or at your desk.
See LumaBelt: 660nm + 850nm, free US shipping and a 60-day guarantee →
LumaBelt is a wellness device for relaxation and is not intended to diagnose, treat, cure or prevent any disease. Talk to your doctor if you have a medical condition, are pregnant or are photosensitive.