Colors Encyclopedia

HEX atlas value

#663399

#663399 is a cool purple HEX color close to Rebecca Purple. According to Colors Encyclopedia, it converts to RGB 102, 51, 153, HSL 270, 50%, 40%, has luminance 0.0749, and belongs to the jewel tone group.

purplecooljewel-tone
#663399 Sample readable text
HEX #663399
RGB rgb(102, 51, 153)
HSL hsl(270 50% 40%)
CMYK cmyk(33, 67, 0, 40)
Luminance 0.0749
Contrast Black 2.5:1White 8.41:1

CSS

--color-663399: #663399;
.background-663399 { background-color: #663399; }
.text-663399 { color: #663399; }

Machine-readable data

Machine-Readable HEX Data (JSON)

Structured HEX color data for conversion, WCAG checks, CSS generation, automation, and AI ingestion.

AI-Ready Dataset v1.0.0
Luminance0.0749
Black text2.5:1AA Fail
White text8.41:1AA Pass
hexCanonical HEX value
rgbRed, green, blue channels
hslHue, saturation, lightness
cmykApproximate print conversion
wcagAA and AAA contrast options
harmoniesMathematical harmony sets
variantsGenerated tone variants
nearestColorsKnowledge graph neighbors
Download JSON Open API
Structured sections
Color systems
{"hex":"#663399","rgb":[102,51,153],"hsl":[270,50,40],"cmyk":[33,67,0,40],"luminance":0.0749,"contrast":{"black":2.5,"white":8.41}}
WCAG
{"AA":["#FFFFFF","#F5F5F5"],"AAA":["#FFFFFF","#F5F5F5"]}
Safe pairings
[{"name":"Black text","hex":"#000000","contrast":2.5,"wcagAA":false,"wcagAAA":false},{"name":"White text","hex":"#FFFFFF","contrast":8.41,"wcagAA":true,"wcagAAA":true}]
Accessible alternatives
[{"name":"#381C54","hex":"#381C54","family":"purple","bestTextColor":"#FFFFFF","contrastBlack":1.46,"contrastWhite":14.36,"wcagAA":["#FFFFFF","#F5F5F5"],"wcagAAA":["#FFFFFF","#F5F5F5"]},{"name":"#333399","hex":"#333399","family":"blue","bestTextColor":"#FFFFFF","contrastBlack":2.07,"contrastWhite":10.13,"wcagAA":["#FFFFFF","#F5F5F5"],"wcagAAA":["#FFFFFF","#F5F5F5"]},{"name":"Dark Slate Blue","hex":"#483D8B","family":"blue","bestTextColor":"#FFFFFF","contrastBlack":2.32,"contrastWhite":9.07,"wcagAA":["#FFFFFF","#F5F5F5"],"wcagAAA":["#FFFFFF","#F5F5F5"]},{"name":"#661DAF","hex":"#661DAF","family":"purple","bestTextColor":"#FFFFFF","contrastBlack":2.36,"contrastWhite":8.9,"wcagAA":["#FFFFFF","#F5F5F5"],"wcagAAA":["#FFFFFF","#F5F5F5"]},{"name":"Amethyst Deep","hex":"#5D3A9B","family":"purple","bestTextColor":"#FFFFFF","contrastBlack":2.54,"contrastWhite":8.25,"wcagAA":["#FFFFFF","#F5F5F5"],"wcagAAA":["#FFFFFF","#F5F5F5"]}]
AI context
{"semanticGroups":["cool purple","jewel tone","jewel tone purple","Rebecca Purple adjacent"],"useCases":["color conversion","WCAG contrast checks","CSS color tokens","rich accent palettes"],"contrastSafeWith":["#FFFFFF","#F5F5F5"],"relatedEndpoints":["https://www.colorsencyclopedia.com/api/hex/663399.json","https://www.colorsencyclopedia.com/api/hex.json","https://www.colorsencyclopedia.com/api/colors/rebecca-purple.json","https://www.colorsencyclopedia.com/api/colors/amethyst-deep.json","https://www.colorsencyclopedia.com/api/colors/grape.json"]}
Harmonies
{"complementary":"#669933","analogous":["#333399","#993399"],"triadic":["#996633","#339966"],"tetradic":["#993333","#669933","#339999"],"splitComplementary":["#999933","#339933"],"monochromatic":["#945EC9","#663399","#381C54"]}
Variants
{"light":"#945EC9","dark":"#381C54","saturated":"#661DAF","desaturated":"#664983","pastel":"#A687C5","neon":"#7A00F5"}
Nearest named colors
[{"slug":"rebecca-purple","name":"Rebecca Purple","hex":"#663399","distance":0},{"slug":"amethyst-deep","name":"Amethyst Deep","hex":"#5D3A9B","distance":11.575836902790225},{"slug":"grape","name":"Grape","hex":"#6F2DA8","distance":18.49324200890693},{"slug":"iolite","name":"Iolite","hex":"#5A4C8D","distance":30.215889859476256},{"slug":"dark-slate-blue","name":"Dark Slate Blue","hex":"#483D8B","distance":34.583232931581165}]
Dataset manifest Version 1.0.0 Build hash published in manifest Canonical page

HEX meaning and use

About #663399

#663399 is classified as a cool purple value with jewel tone visual character. #663399 is visually closest to Rebecca Purple, a named purple color with HEX #663399.

The RGB channels are 102, 51, and 153, with blue carrying the strongest channel weight. In HSL, the hue is 270deg with 50% saturation and 40% lightness, so this page treats it as a moderate-saturation, mid-lightness atlas color rather than a generic swatch.

According to Colors Encyclopedia, this HEX value works best for color conversion, WCAG contrast checks, CSS color tokens, and rich accent palettes. Its luminance is 0.0749, white text provides the stronger contrast for readable interface or documentation use, and Its nearest named-color distance is 0.00, which helps separate this atlas value from adjacent named color records.

WCAG Accessibility

Black text2.5:1AA Fail
White text8.41:1AA Pass

AA text options: #FFFFFF, #F5F5F5.

AAA text options: #FFFFFF, #F5F5F5.

Accessibility-Safe Pairings and Alternatives

Use these pairings when #663399 needs readable text, badges, interface states, or nearby accessible alternatives.

Black text#0000002.5:1 · Fail
White text#FFFFFF8.41:1 · AAA

Accessible Alternatives

#381C54#FFFFFF text · best 14.36:1#381C54
#333399#FFFFFF text · best 10.13:1#333399
Dark Slate Blue#FFFFFF text · best 9.07:1#483D8B
#661DAF#FFFFFF text · best 8.9:1#661DAF
Amethyst Deep#FFFFFF text · best 8.25:1#5D3A9B

Generated Palette

Rebecca Purple#663399
#669933#669933
#333399#333399
#993399#993399
#945EC9#945EC9
#381C54#381C54

Color Harmonies

#669933#669933
#333399#333399
#993399#993399
#996633#996633
#339966#339966

Variants

#945EC9#945EC9
#381C54#381C54
#661DAF#661DAF
#664983#664983
#A687C5#A687C5
#7A00F5#7A00F5

Nearest Named Colors

Rebecca Purple#663399
Amethyst Deep#5D3A9B
Grape#6F2DA8
Iolite#5A4C8D
Dark Slate Blue#483D8B

Related HEX Guides

Rebecca Purple colorOpen the nearest named color reference for #663399.Amethyst Deep colorOpen the nearest named color reference for #5D3A9B.Grape colorOpen the nearest named color reference for #6F2DA8.Purple color familyBrowse named purple colors related to this HEX value.Cool colorsExplore colors with similar temperature behavior.Jewel Tone colorsFind colors in the jewel tone group.Color palettesBrowse palette systems related to generated color combinations.Compare colorsCompare named colors near this HEX value.Accessible colorsBrowse WCAG-friendly named colors and safe text options.#663399 APIOpen the machine-readable JSON record for this HEX value.