HueComb

Helvetia Red

#f00000

A red that is about as vivid as sRGB can show at this lightness. It is mid — the hardest range to put text on, either colour struggles.

Hex

#f00000

RGB

240, 0, 0

OKLCh

60.0% 0.246 29.2°

CIELAB (D50)

51.1, 77.2, 66.8

What is true of this colour, and of no other

  • 11 other named colours sit within ΔE00 2 of it — this part of the space is crowded, and the names here are finer distinctions than most people make.
  • It sits exactly on the sRGB boundary: at this lightness and hue the gamut has nothing left, and a wider display would show a more colourful version of it.
  • As text on white it measures APCA Lc 67.9; on black, Lc -33.8. The sign is the polarity, which the WCAG ratio discards.
  • Built into an eleven-step scale, 10 of the 10 adjacent pairs stay ΔE00 2 apart — see the ramp.
  • protanopia and deuteranopia and tritanopia shift it by ΔE00 43.8 and 46.0 and 50.6 — no red cone.

Text on this colour

White text

4.46:1 — large text only

Black text

4.71:1 — passes AA

Black text is the better of the two at4.71:1. That is enough for body text.

As text on white, it needs to change

#ef0000 is the nearest colour of the same hue that passes AA on white, at 4.50:1. Only the lightness moved, and some saturation was given up to stay inside sRGB.

Try it against your own background

The same colour, with one cone missing

As you see it

#f00000

protanopia

#58580b · ΔE00 43.8

deuteranopia

#8a8a00 · ΔE00 46.0

tritanopia

#afaf00 · ΔE00 50.6

Run a whole palette through all three

The twelve nearest named colours

Ranked by CIEDE2000 — perceptual distance, not hex arithmetic. The closest isSpectrum Red at ΔE00 0.435: below 1.0 — an ordinary observer cannot tell these apart, even side by side. What the numbers mean.

7 of these have no page of their own: pages exist for the 4,961 colours the dataset marks as good names.