Color on the web is expressed in several genuinely different coordinate systems, not just different string syntaxes for the same underlying value. HEX and RGB both describe color as red, green, and blue channel intensities — HEX is just RGB packed into a compact hexadecimal string — but HSL describes the exact same color space using hue (a position on the color wheel), saturation (how far from gray), and lightness, which is a far more intuitive model for adjusting a color rather than deriving a new one, since 'make it 20% lighter' is a trivial change to HSL's lightness channel and a non-obvious one across all three RGB channels simultaneously.
Converting between them isn't just reformatting — RGB to HSL requires actual trigonometric-adjacent math (finding the max and min channel values, computing hue based on which channel is dominant), and named CSS colors like rebeccapurple or cornflowerblue map to specific, standardized RGB triples defined in the CSS Color specification, not anything derived algorithmically from the name.
The genuinely load-bearing use of a color conversion tool, beyond format translation, is contrast checking: WCAG defines minimum contrast ratios for text against its background — 4.5:1 for normal text at the AA level, 3:1 for large text, and 7:1 for AA A — computed from the relative luminance of both colors, which is itself a weighted, non-linear function of the RGB channels (green contributes far more to perceived luminance than blue). A color pairing that looks reasonably legible to a designer's eye can still fail these thresholds, particularly for users with low vision.
This converter parses any of the common color syntaxes, outputs every other format simultaneously, and computes the WCAG contrast ratio of the input color against both pure black and pure white text, flagging which combinations pass AA and AAA thresholds and which don't.
Edge cases worth knowing
- An 8-digit HEX color with an alpha channel
- #e0a75eCC includes a two-digit alpha suffix (CC ≈ 80% opacity) — a format supported by modern CSS but sometimes mishandled by tools expecting only 6-digit HEX. This converter parses the alpha channel separately and carries it through to the RGBA and HSLA outputs.
- A color that passes AA contrast but fails AAA
- The gap between AA (4.5:1 for normal text) and AAA (7:1) is substantial — many reasonable-looking color pairings clear the lower bar but not the higher one. This converter reports both thresholds explicitly rather than a single pass/fail so you can decide which standard your project targets.
- A named color with no exact HEX equivalent you'd guess
- CSS named colors like 'rebeccapurple' (#663399) or 'papayawhip' (#FFEFD5) map to specific values defined in the spec, not anything derivable from the name itself. This converter resolves the full CSS4 named-color list rather than only the original 16 basic HTML colors.
Common mistakes
- Choosing a text/background color pairing based on how it looks on one particular monitor without checking the computed contrast ratio.
- Assuming a color 'looks light enough' or 'looks dark enough' to pass accessibility contrast without calculating relative luminance, which weights channels unevenly.
- Confusing HSL's lightness channel with perceived brightness — two colors with identical lightness values can look noticeably different in actual perceived brightness depending on hue and saturation.
- Forgetting that an alpha channel changes the effective contrast against whatever is rendered behind it, not just against the nominal background color.