Colors Encyclopedia

HEX atlas value

#B21510

#B21510 is a warm red HEX color close to Firebrick. According to Colors Encyclopedia, it converts to RGB 178, 21, 16, HSL 2, 84%, 38%, has luminance 0.1004, and belongs to the vibrant group.

redwarmvibrant
#B21510 Sample readable text
HEX #B21510
RGB rgb(178, 21, 16)
HSL hsl(2 84% 38%)
CMYK cmyk(0, 88, 91, 30)
Luminance 0.1004
Contrast Black 3.01:1White 6.98:1

CSS

--color-b21510: #B21510;
.background-b21510 { background-color: #B21510; }
.text-b21510 { color: #B21510; }

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
Luminance0.1004
Black text3.01:1AA Fail
White text6.98:1AA 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":"#B21510","rgb":[178,21,16],"hsl":[2,84,38],"cmyk":[0,88,91,30],"luminance":0.1004,"contrast":{"black":3.01,"white":6.98}}
WCAG
{"AA":["#FFFFFF","#F5F5F5"],"AAA":[]}
Safe pairings
[{"name":"Black text","hex":"#000000","contrast":3.01,"wcagAA":false,"wcagAAA":false},{"name":"White text","hex":"#FFFFFF","contrast":6.98,"wcagAA":true,"wcagAAA":false}]
Accessible alternatives
[{"name":"#5E0B08","hex":"#5E0B08","family":"red","bestTextColor":"#FFFFFF","contrastBlack":1.53,"contrastWhite":13.74,"wcagAA":["#FFFFFF","#F5F5F5"],"wcagAAA":["#FFFFFF","#F5F5F5"]},{"name":"Ruby Red","hex":"#9B111E","family":"red","bestTextColor":"#FFFFFF","contrastBlack":2.49,"contrastWhite":8.43,"wcagAA":["#FFFFFF","#F5F5F5"],"wcagAAA":["#FFFFFF","#F5F5F5"]},{"name":"#10ADB2","hex":"#10ADB2","family":"cyan","bestTextColor":"#000000","contrastBlack":7.64,"contrastWhite":2.75,"wcagAA":["#000000","#1A1A1A"],"wcagAAA":["#000000"]},{"name":"#9D2925","hex":"#9D2925","family":"red","bestTextColor":"#FFFFFF","contrastBlack":2.78,"contrastWhite":7.56,"wcagAA":["#FFFFFF","#F5F5F5"],"wcagAAA":["#FFFFFF"]},{"name":"Anodized Red","hex":"#B00020","family":"red","bestTextColor":"#FFFFFF","contrastBlack":2.87,"contrastWhite":7.33,"wcagAA":["#FFFFFF","#F5F5F5"],"wcagAAA":["#FFFFFF"]}]
AI context
{"semanticGroups":["warm red","vibrant","vibrant red","Firebrick adjacent"],"useCases":["color conversion","WCAG contrast checks","CSS color tokens","high-energy accents","high-attention visual states"],"contrastSafeWith":["#FFFFFF","#F5F5F5"],"relatedEndpoints":["https://www.colorsencyclopedia.com/api/hex/b21510.json","https://www.colorsencyclopedia.com/api/hex.json","https://www.colorsencyclopedia.com/api/colors/firebrick.json","https://www.colorsencyclopedia.com/api/colors/tool-red.json","https://www.colorsencyclopedia.com/api/colors/venetian-red.json"]}
Harmonies
{"complementary":"#10ADB2","analogous":["#B2105B","#B26610"],"triadic":["#10B215","#1510B2"],"tetradic":["#5BB210","#10ADB2","#6610B2"],"splitComplementary":["#10B266","#105BB2"],"monochromatic":["#ED3731","#B21510","#5E0B08"]}
Variants
{"light":"#ED3731","dark":"#5E0B08","saturated":"#C20600","desaturated":"#9D2925","pastel":"#E26460","neon":"#EB0800"}
Nearest named colors
[{"slug":"firebrick","name":"Firebrick","hex":"#B22222","distance":22.20360331117452},{"slug":"tool-red","name":"Tool Red","hex":"#B11226","distance":22.22611077089287},{"slug":"venetian-red","name":"Venetian Red","hex":"#C80815","distance":26.038433132583073},{"slug":"anodized-red","name":"Anodized Red","hex":"#B00020","distance":26.476404589747453},{"slug":"ruby-red","name":"Ruby Red","hex":"#9B111E","distance":27.2213151776324}]
Dataset manifest Version 1.0.0 Build hash published in manifest Canonical page

HEX meaning and use

About #B21510

#B21510 is classified as a warm red value with vibrant visual character. #B21510 is visually closest to Firebrick, a named red color with HEX #B22222.

The RGB channels are 178, 21, and 16, with red carrying the strongest channel weight. In HSL, the hue is 2deg with 84% saturation and 38% lightness, so this page treats it as a high-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 high-energy accents. Its luminance is 0.1004, white text provides the stronger contrast for readable interface or documentation use, and Its nearest named-color distance is 22.20, which helps separate this atlas value from adjacent named color records.

WCAG Accessibility

Black text3.01:1AA Fail
White text6.98:1AA Pass

AA text options: #FFFFFF, #F5F5F5.

AAA text options: none in seed set.

Accessibility-Safe Pairings and Alternatives

Use these pairings when #B21510 needs readable text, badges, interface states, or nearby accessible alternatives.

Black text#0000003.01:1 · Fail
White text#FFFFFF6.98:1 · AA

Accessible Alternatives

#5E0B08#FFFFFF text · best 13.74:1#5E0B08
Ruby Red#FFFFFF text · best 8.43:1#9B111E
#10ADB2#000000 text · best 7.64:1#10ADB2
#9D2925#FFFFFF text · best 7.56:1#9D2925
Anodized Red#FFFFFF text · best 7.33:1#B00020

Generated Palette

#B21510#B21510
#10ADB2#10ADB2
#B2105B#B2105B
#B26610#B26610
#ED3731#ED3731
#5E0B08#5E0B08

Color Harmonies

#10ADB2#10ADB2
#B2105B#B2105B
#B26610#B26610
#10B215#10B215
#1510B2#1510B2

Variants

#ED3731#ED3731
#5E0B08#5E0B08
#C20600#C20600
#9D2925#9D2925
#E26460#E26460
#EB0800#EB0800

Nearest Named Colors

Firebrick#B22222
Tool Red#B11226
Venetian Red#C80815
Anodized Red#B00020
Ruby Red#9B111E

Related HEX Guides

Firebrick colorOpen the nearest named color reference for #B22222.Tool Red colorOpen the nearest named color reference for #B11226.Venetian Red colorOpen the nearest named color reference for #C80815.Red color familyBrowse named red colors related to this HEX value.Warm colorsExplore colors with similar temperature behavior.Vibrant colorsFind colors in the vibrant 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.#B21510 APIOpen the machine-readable JSON record for this HEX value.