Inspect FireBrick (#B22222) in HEX, RGB, HSL, LCH and OKLCH, check its contrast, and copy the value you need.
FireBrick
#B22222
White text reads best on this background, at 6.68:1.
FireBrick is one of the 148 CSS named colors, and resolves to #B22222 in every browser. In numbers that is rgb(178, 34, 34) and hsl(0, 68%, 42%). Perceptually it is a mid-toned, moderately saturated color: OKLCH puts its lightness at 50% and its chroma at 0.18. It sits in the reds at 27 degrees of OKLCH hue, and reads as a warm color.
White text clears WCAG AA on a FireBrick background at 6.68:1. 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 FireBrick, measured with CIEDE2000, are Brown (#A52A2A), DarkRed (#8B0000), Crimson (#DC143C). If FireBrick is not quite right, those are the nearest keywords to try before reaching for a custom value.
HEX
#B22222
RGB
rgb(178, 34, 34)
HSL
hsl(0, 68%, 42%)
HWB
hwb(0 13% 30%)
CMYK
cmyk(0%, 81%, 81%, 30%)
LAB
lab(39.83 56.59 39.19)
LCH
lch(39.83 68.83 34.7)
OKLCH
oklch(49.68% 0.1797 26.81)
WCAG asks for 4.5:1 between body text and its background. On #B22222 white text measures 6.68:1 and black text 3.14:1, so white clears it and black does not.
White text on FireBrick
WCAG 2.2
6.68:1
APCA
Lc 86
Passes AA body text
Fails AAA body text
Passes AA large text
Black text on FireBrick
WCAG 2.2
3.14:1
APCA
Lc 22
Fails AA body text
Fails AAA body text
Passes AA large text
Check FireBrick against any other color in the contrast checker.
FireBrick sits at 50% OKLCH lightness. Holding its hue and chroma and moving only that value carries it up to #FFF6F5 and down to #140000, which keeps the family recognizable instead of letting it drift toward gray the way a plain HSL ramp does.
#D4463F
20% lighter
#F7665C
40% lighter
#FF998E
60% lighter
#FFCAC3
80% lighter
#FFF6F5
100% lighter
#95000D
20% darker
#710007
40% darker
#500004
60% darker
#300001
80% darker
#140000
100% darker
Build a full accessible scale from #B22222 in the shade generator.
Hues rotated around #B22222 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.
FireBrick sits at 27 degrees. Rotating it a half turn lands on 207 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 FireBrick at 357 and 57 degrees. They stay close enough to read as the same family, which is what you want for hover states, secondary surfaces and gradients.
27, 147 and 267 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 207 degrees, this pair flanks it at 177 and 237. You keep most of the contrast of a complementary pairing while losing the harshness.
Explore more combinations around FireBrick on the color wheel.
The biggest shift is under protanopia, where #B22222 reads as #383221, 31.8 CIEDE2000 units away. If FireBrick is the only thing marking a state or a series, roughly one viewer in twelve will miss it.
Protanopia
#383221
Deuteranopia
#574A20
Tritanopia
#D71723
Achromatopsia
#414141
The nearest CSS keywords to #B22222, ranked by perceptual distance rather than by how close their hex digits happen to look.