Inspect Sienna (#A0522D) in HEX, RGB, HSL, LCH and OKLCH, check its contrast, and copy the value you need.
Sienna
#A0522D
White text reads best on this background, at 5.62:1.
Sienna is one of the 148 CSS named colors, and resolves to #A0522D in every browser. In numbers that is rgb(160, 82, 45) and hsl(19, 56%, 40%). Perceptually it is a mid-toned, moderately saturated color: OKLCH puts its lightness at 53% and its chroma at 0.115. It sits in the browns at 45 degrees of OKLCH hue, and reads as a warm color.
White text clears WCAG AA on a Sienna background at 5.62:1. 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 Sienna, measured with CIEDE2000, are SaddleBrown (#8B4513), FireBrick (#B22222), Brown (#A52A2A). If Sienna is not quite right, those are the nearest keywords to try before reaching for a custom value.
HEX
#A0522D
RGB
rgb(160, 82, 45)
HSL
hsl(19, 56%, 40%)
HWB
hwb(19 18% 37%)
CMYK
cmyk(0%, 49%, 72%, 37%)
LAB
lab(44.27 30.91 36.35)
LCH
lch(44.27 47.71 49.62)
OKLCH
oklch(52.65% 0.1151 44.6)
WCAG asks for 4.5:1 between body text and its background. On #A0522D white text measures 5.62:1 and black text 3.74:1, so white clears it and black does not.
White text on Sienna
WCAG 2.2
5.62:1
APCA
Lc 82
Passes AA body text
Fails AAA body text
Passes AA large text
Black text on Sienna
WCAG 2.2
3.74:1
APCA
Lc 26
Fails AA body text
Fails AAA body text
Passes AA large text
Check Sienna against any other color in the contrast checker.
Sienna sits at 53% OKLCH lightness. Holding its hue and chroma and moving only that value carries it up to #FFF6F3 and down to #100200, which keeps the family recognizable instead of letting it drift toward gray the way a plain HSL ramp does.
#BE6D48
20% lighter
#DC8963
40% lighter
#FBA57F
60% lighter
#FFCEB9
80% lighter
#FFF6F3
100% lighter
#863A13
20% darker
#692700
40% darker
#491800
60% darker
#2B0B00
80% darker
#100200
100% darker
Build a full accessible scale from #A0522D in the shade generator.
Hues rotated around #A0522D 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.
Sienna sits at 45 degrees. Rotating it a half turn lands on 225 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 Sienna at 15 and 75 degrees. They stay close enough to read as the same family, which is what you want for hover states, secondary surfaces and gradients.
45, 165 and 285 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 225 degrees, this pair flanks it at 195 and 255. You keep most of the contrast of a complementary pairing while losing the harshness.
Explore more combinations around Sienna on the color wheel.
The biggest shift is under achromatopsia, where #A0522D reads as #606060, 23.7 CIEDE2000 units away. If Sienna is the only thing marking a state or a series, roughly one viewer in twelve will miss it.
Protanopia
#65572B
Deuteranopia
#77662D
Tritanopia
#BB4647
Achromatopsia
#606060
The nearest CSS keywords to #A0522D, ranked by perceptual distance rather than by how close their hex digits happen to look.