Inspect MediumAquaMarine (#66CDAA) in HEX, RGB, HSL, LCH and OKLCH, check its contrast, and copy the value you need.
MediumAquaMarine
#66CDAA
Black text reads best on this background, at 10.88:1.
MediumAquaMarine is one of the 148 CSS named colors, and resolves to #66CDAA in every browser. In numbers that is rgb(102, 205, 170) and hsl(160, 51%, 60%). Perceptually it is a light, moderately saturated color: OKLCH puts its lightness at 78% and its chroma at 0.11. It sits in the cyans at 169 degrees of OKLCH hue, and reads as a cool color.
White text only reaches 1.93:1 here, so black text is the safer pairing at 10.88:1. That combination of lightness and chroma makes it a workable mid-tone, the kind of value that lands in the middle of a shade scale.
The closest CSS named colors to MediumAquaMarine, measured with CIEDE2000, are Turquoise (#40E0D0), DarkSeaGreen (#8FBC8F), MediumTurquoise (#48D1CC). If MediumAquaMarine is not quite right, those are the nearest keywords to try before reaching for a custom value.
HEX
#66CDAA
RGB
rgb(102, 205, 170)
HSL
hsl(160, 51%, 60%)
HWB
hwb(160 40% 20%)
CMYK
cmyk(50%, 0%, 17%, 20%)
LAB
lab(75.55 -37.75 7.83)
LCH
lch(75.55 38.56 168.28)
OKLCH
oklch(77.67% 0.1098 168.82)
WCAG asks for 4.5:1 between body text and its background. On #66CDAA white text measures 1.93:1 and black text 10.88:1, so black clears it and white does not.
White text on MediumAquaMarine
WCAG 2.2
1.93:1
APCA
Lc 41
Fails AA body text
Fails AAA body text
Fails AA large text
Black text on MediumAquaMarine
WCAG 2.2
10.88:1
APCA
Lc 67
Passes AA body text
Passes AAA body text
Passes AA large text
Check MediumAquaMarine against any other color in the contrast checker.
MediumAquaMarine sits at 78% OKLCH lightness. Holding its hue and chroma and moving only that value carries it up to #E7FFF5 and down to #000805, which keeps the family recognizable instead of letting it drift toward gray the way a plain HSL ramp does.
#74DAB7
20% lighter
#81E8C4
40% lighter
#8FF5D1
60% lighter
#AEFFE0
80% lighter
#E7FFF5
100% lighter
#37A382
20% darker
#007A5D
40% darker
#00503C
60% darker
#00291E
80% darker
#000805
100% darker
Build a full accessible scale from #66CDAA in the shade generator.
Hues rotated around #66CDAA in OKLCH, then pulled back into the sRGB gamut. Each swatch is labelled with the nearest CSS named color so you have a keyword to start from.
MediumAquaMarine sits at 169 degrees. Rotating it a half turn lands on 349 degrees, the hue directly opposite. It is the strongest pairing you can make without changing lightness, and the one most likely to vibrate if you use both at full chroma.
The neighbors of MediumAquaMarine at 139 and 199 degrees. They stay close enough to read as the same family, which is what you want for hover states, secondary surfaces and gradients.
169, 289 and 49 degrees divide the wheel into thirds. Balanced enough to carry a whole palette without one color dominating the other two.
Instead of the complement at 349 degrees, this pair flanks it at 319 and 19. You keep most of the contrast of a complementary pairing while losing the harshness.
Explore more combinations around MediumAquaMarine on the color wheel.
The biggest shift is under deuteranopia, where #66CDAA reads as #AFAEAC, 23.9 CIEDE2000 units away. If MediumAquaMarine is the only thing marking a state or a series, roughly one viewer in twelve will miss it.
Protanopia
#C4BEA9
Deuteranopia
#AFAEAC
Tritanopia
#52D0C2
Achromatopsia
#B4B5B5
The nearest CSS keywords to #66CDAA, ranked by perceptual distance rather than by how close their hex digits happen to look.