#FFBF00

The closest CSS color name to this value is "gold", which is not the same color. Everything below is arithmetic on the value itself.

HEX

#FFBF00

RGB

255, 191, 0

HSL

45, 100%, 50%

Closest CSS name

gold (not exact)

Contrast with white

1.65:1

Contrast with black

12.70:1

Reading the contrast figures

Those two ratios are WCAG 2.1 contrast, measured between this color and plain white or plain black. They are the numbers that decide whether text of that color would be readable on this background: 4.5:1 is the threshold for normal text under success criterion 1.4.3, and 3:1 for large text. A ratio is one fact about a pair of colors, not a verdict on whether a design is accessible.

This exact value is what Amber Screen paints, full screen.

Other colors

Sixteen colors have pages like this one: the values this site already uses in its own tools. The Color Picker shows any other shade full screen and puts it in the address, so you can share it without a page ever being created for it. The Color Converter writes a value three ways, and the Contrast Checker measures any pair rather than only black and white.