Inspect Ivory (#FFFFF0) in HEX, RGB, HSL, LCH and OKLCH, check its contrast, and copy the value you need.
Ivory
#FFFFF0
Black text reads best on this background, at 20.81:1.
Ivory is one of the 148 CSS named colors, and resolves to #FFFFF0 in every browser. In numbers that is rgb(255, 255, 240) and hsl(60, 100%, 97%). Perceptually it is a very light, near-neutral color: OKLCH puts its lightness at 100% and its chroma at 0.02. It carries almost no chroma, so it behaves as a neutral rather than as a hue, and belongs with the off-whites.
White text only reaches 1.01:1 here, so black text is the safer pairing at 20.81:1. Because it is this light, Ivory works best as a page or card background with dark text over it.
The closest CSS named colors to Ivory, measured with CIEDE2000, are FloralWhite (#FFFAF0), OldLace (#FDF5E6), Beige (#F5F5DC). If Ivory is not quite right, those are the nearest keywords to try before reaching for a custom value.
HEX
#FFFFF0
RGB
rgb(255, 255, 240)
HSL
hsl(60, 100%, 97%)
HWB
hwb(60 94% 0%)
CMYK
cmyk(0%, 0%, 6%, 0%)
LAB
lab(99.7 -1.9 7.19)
LCH
lch(99.7 7.44 104.78)
OKLCH
oklch(99.6% 0.0196 106.75)
WCAG asks for 4.5:1 between body text and its background. On #FFFFF0 white text measures 1.01:1 and black text 20.81:1, so black clears it and white does not.
White text on Ivory
WCAG 2.2
1.01:1
APCA
Lc 0
Fails AA body text
Fails AAA body text
Fails AA large text
Black text on Ivory
WCAG 2.2
20.81:1
APCA
Lc 105
Passes AA body text
Passes AAA body text
Passes AA large text
Check Ivory against any other color in the contrast checker.
Ivory sits at 100% OKLCH lightness. Holding its hue and chroma and moving only that value carries it down to #060601, which keeps the family recognizable instead of letting it drift toward gray the way a plain HSL ramp does.
#C5C5B7
20% darker
#8F8F81
40% darker
#5C5C4F
60% darker
#2E2D22
80% darker
#060601
100% darker
Build a full accessible scale from #FFFFF0 in the shade generator.
The biggest shift is under achromatopsia, where #FFFFF0 reads as #FEFEFE, 6.9 CIEDE2000 units away. If Ivory is the only thing marking a state or a series, roughly one viewer in twelve will miss it.
Protanopia
#FFFEEF
Deuteranopia
#FFFEF0
Tritanopia
#FFFDFA
Achromatopsia
#FEFEFE
The nearest CSS keywords to #FFFFF0, ranked by perceptual distance rather than by how close their hex digits happen to look.