399 nm to RGB & Color Calculator

Why You See This Color (399 nm)

At 399 nm, monochromatic light stimulates human Short-wavelength (S) retinal cone photoreceptors with minimal activation of Medium (M) and Long (L) cones. The brain interprets this high-frequency electromagnetic stimulus (approximately 751.36 THz, carrying 3.107 eV per quantum photon) as deep violet. Because the eye's photopic luminous efficiency V(λ) drops sharply toward the near-ultraviolet threshold, this wavelength requires greater radiant flux to match the perceived brightness of green light.