Every red light therapy device lists wavelengths in nanometers — usually 660nm and 850nm — but most product pages never explain what those numbers actually mean for how you use the device. Here's the practical breakdown.
660nm vs. 850nm: What's the Difference?
The wavelength determines how deep the light travels into tissue:
- 660nm (visible red light) is absorbed mostly in the upper layers of skin, penetrating roughly 2-4mm. It's the wavelength most associated with surface-level, skin-focused use.
- 850nm (near-infrared, invisible to the eye) is absorbed less by surface tissue, so more of it travels deeper — commonly cited at 3-5cm or more, reaching muscle, joints, and connective tissue.
This is a useful simplification, not a rigid rule — dose, power, and total session time all affect results too, not wavelength alone. That said, it explains why most quality devices, including our full Red Light Pro Devices lineup, combine both wavelengths in a single panel: 660nm for surface-level coverage, 850nm for deeper reach, delivered at the same time.
How Long Should a Session Be?
Most research protocols and device manufacturers land in a similar range:
- Session length: 10-20 minutes per area
- Distance from device: roughly 6-12 inches
- Frequency: 3-5 sessions per week
Dual-wavelength devices don't require longer sessions than single-wavelength panels — both wavelengths are delivered simultaneously, not sequentially, so you're not doubling your time.
When Will You Notice a Difference?
Consistency matters more than any single session. Most protocols suggest sticking with a routine for 4-6 weeks before evaluating results, since photobiomodulation works through cumulative, repeated exposure rather than a one-time effect.
Choosing Between Our Devices
All of our panels use the same 660nm + 850nm dual-wavelength approach — the difference between models comes down to coverage area and format, not wavelength quality:
- Targeted pads (hands, feet) suit focused, specific-area use.
- Large pads and the Full Body System suit whole-body or multi-area sessions in a single go.
- The VersaDome Pro 2-in-1 suits anyone who wants both face and body use from one device.
The Bottom Line
660nm and 850nm aren't competing options — they work together, targeting different tissue depths in the same session. Distance, session length, and consistency matter as much as the wavelength spec itself.
Browse the full Red Light Pro Devices collection to compare coverage area and format.
This article is for general informational purposes and does not constitute medical advice. Consult a healthcare provider with questions about red light therapy and your specific health circumstances.