Inspect SlateBlue (#6A5ACD) in HEX, RGB, HSL, LCH and OKLCH, check its contrast, and copy the value you need.
SlateBlue
#6A5ACD
White text reads best on this background, at 5.31:1.
SlateBlue is one of the 148 CSS named colors, and resolves to #6A5ACD in every browser. In numbers that is rgb(106, 90, 205) and hsl(248, 53%, 58%). Perceptually it is a mid-toned, moderately saturated color: OKLCH puts its lightness at 54% and its chroma at 0.171. It sits in the purples at 286 degrees of OKLCH hue, and reads as a cool color.
White text clears WCAG AA on a SlateBlue background at 5.31:1. 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 SlateBlue, measured with CIEDE2000, are MediumSlateBlue (#7B68EE), RoyalBlue (#4169E1), MediumPurple (#9370DB). If SlateBlue is not quite right, those are the nearest keywords to try before reaching for a custom value.
HEX
#6A5ACD
RGB
rgb(106, 90, 205)
HSL
hsl(248, 53%, 58%)
HWB
hwb(248 35% 20%)
CMYK
cmyk(48%, 56%, 0%, 20%)
LAB
lab(44.57 29.65 -58.72)
LCH
lch(44.57 65.78 296.79)
OKLCH
oklch(54.36% 0.1712 285.54)
WCAG asks for 4.5:1 between body text and its background. On #6A5ACD white text measures 5.31:1 and black text 3.96:1, so white clears it and black does not.
White text on SlateBlue
WCAG 2.2
5.31:1
APCA
Lc 81
Passes AA body text
Fails AAA body text
Passes AA large text
Black text on SlateBlue
WCAG 2.2
3.96:1
APCA
Lc 27
Fails AA body text
Fails AAA body text
Passes AA large text
Check SlateBlue against any other color in the contrast checker.
SlateBlue sits at 54% OKLCH lightness. Holding its hue and chroma and moving only that value carries it up to #F8F8FF and down to #06001F, which keeps the family recognizable instead of letting it drift toward gray the way a plain HSL ramp does.
#8275EB
20% lighter
#9C94FF
40% lighter
#B9B6FF
60% lighter
#D7D7FF
80% lighter
#F8F8FF
100% lighter
#5440B1
20% darker
#3F2495
40% darker
#2C0078
60% darker
#180049
80% darker
#06001F
100% darker
Build a full accessible scale from #6A5ACD in the shade generator.
Hues rotated around #6A5ACD 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.
SlateBlue sits at 286 degrees. Rotating it a half turn lands on 106 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 SlateBlue at 256 and 316 degrees. They stay close enough to read as the same family, which is what you want for hover states, secondary surfaces and gradients.
286, 46 and 166 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 106 degrees, this pair flanks it at 76 and 136. You keep most of the contrast of a complementary pairing while losing the harshness.
Explore more combinations around SlateBlue on the color wheel.
The biggest shift is under achromatopsia, where #6A5ACD reads as #666666, 27 CIEDE2000 units away. If SlateBlue is the only thing marking a state or a series, roughly one viewer in twelve will miss it.
Protanopia
#4567D3
Deuteranopia
#4664C9
Tritanopia
#5A6A7D
Achromatopsia
#666666
The nearest CSS keywords to #6A5ACD, ranked by perceptual distance rather than by how close their hex digits happen to look.