Blue is the CSS named color #0000FF — rgb(0, 0, 255), hsl(240, 100%, 50%). Its relative luminance is 0.072, giving 8.59:1 against white and 2.44:1 against black, so it works as a text color on white.
| HEX | #0000FF |
|---|---|
| RGB | rgb(0, 0, 255) |
| HSL | hsl(240, 100%, 50%) |
| Relative luminance | 0.0722 |
| Contrast on white | 8.59:1 AA pass |
| Contrast on black | 2.44:1 AA fail |
Built by mixing blue toward white (four steps) and toward black (four steps) while keeping the hue. Use the shades generator for a different step count or to add harmony sets.
Closest by CIELAB distance (ΔE76). For perceptual matching in a design system, compare in OKLab before locking a token.
blue is #0000FF, which is rgb(0, 0, 255) and hsl(240, 100%, 50%). It is one of the 148 CSS named colors defined by the CSS Color Module Level 4.
Blue has a relative luminance of 0.072 on a 0–1 scale, so it is a dark color. Against white it scores 8.59:1; against black, 2.44:1.
blue reaches 8.59:1 against white, which clears WCAG 2.2 AA for normal text (4.5:1) at any size.