Light for hair / The basics
Look past
the light count.
Five checks to make before comparing caps and helmets.
Start with the exact model
A brand may sell several caps with different light sources, power or schedules. Check that the product page and manual refer to the model you are considering.
Keep the units separate
mW describes power. mW/cm² describes power over an area. J describes energy, while J/cm² describes energy over an area. You cannot turn total milliwatts into a dose per square centimetre without more information.
Do not compare time by itself
A six-minute routine is not automatically weaker than a thirty-minute routine. The light output and how it reaches the scalp also matter. Follow the schedule in the device’s own manual.
Treat extra wavelengths as a difference
Most devices here list red light. The Dr. Renú cap also lists 850 nm near-infrared. An extra wavelength does not, by itself, establish better hair growth.
Read the source note
Some current pages contradict themselves. Some figures are only available in the older comparison. Our notes keep those gaps visible rather than filling them in.
These are checks for reading specifications, not personal treatment advice. A clinician can help identify why hair is thinning and discuss suitable options.
Compare all five devices