Rubber Ducky

#facf58

A yellow that is muted. It is very light — it works as a page background, not as text.

Hex

#facf58

RGB

250, 207, 88

OKLCh

87.0% 0.143 89.1°

CIELAB (D50)

85.3, 6.5, 63.0

What is true of this colour, and of no other

25 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 uses 88% of the chroma sRGB can show at this lightness and hue — close enough to the boundary that a wider display would show it slightly more vividly.
As text on white it measures APCA Lc 22.8; on black, Lc -80.5. 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 11.5 and 11.6 and 13.1 — no red cone.

Text on this colour

White text

1.49:1 — fails AA

Black text

14.13:1 — passes AA

Black text is the better of the two at14.13:1. That is enough for body text.

As text on white, it needs to change

#937300 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

#facf58

protanopia

#d4d459 · ΔE00 11.5

deuteranopia

#dddd55 · ΔE00 11.6

tritanopia

#e6e600 · ΔE00 13.1

Run a whole palette through all three

The twelve nearest named colours

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

Beach PartyΔE00 0.435 · #fbd05c
KournikovaΔE00 0.888 · #f9d054
SolarizedΔE00 0.97 · #fbcf4f
Glowing ReviewsΔE00 0.975 · #ffd15a
Dandy LionΔE00 0.976 · #facc51
RadlerΔE00 1.064 · #ffd15c
Go BananasΔE00 1.217 · #f7ca50
Melted ButterΔE00 1.265 · #ffcf53
Evening StarΔE00 1.373 · #ffd160
Minion YellowΔE00 1.385 · #fece4e
Casandora YellowΔE00 1.461 · #fece5a
Canary DiamondΔE00 1.484 · #ffce52

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