What is the best red light therapy wavelength?

630 nm: shallow, strongly absorbed at the surface. Common in masks and skin-focused panels.

660 nm: the workhorse red wavelength. Still surface-oriented but reaching slightly deeper, and the most commonly studied red band for skin outcomes.

810 nm: near-infrared with good tissue penetration, well represented in the pain and neurological research literature.

850 nm: the most common near-infrared wavelength in consumer and commercial devices, favoured for muscle and joint depth.

Light has to reach the tissue you're trying to affect. Aiming 660 nm at a deep joint mostly treats the skin above it; aiming 850 nm at fine lines is working past the layer you care about.

This is the practical reason multi-wavelength devices dominate: your goals rarely sit at a single depth, and near-infrared is invisible, so it costs you nothing in comfort to have it running alongside red.

Tolerance matters too. A device stating '660 nm ±10 nm' from binned LEDs is telling you something; one stating 'red light' is not.

Skin and appearance: prioritise red, 630–660 nm, delivered close to the skin. Masks and contact devices do well here.

Muscle recovery and joint comfort: prioritise near-infrared, 810–850 nm, with enough irradiance to reach depth.

Whole-body and mixed goals: both, which is how beds are configured — red for the skin surface across your whole body and near-infrared reaching the tissue underneath in the same session.

Hair: dedicated devices generally centre on red around 650–670 nm, applied in contact with the scalp.