Blue3
blue3 · #0000CD
HEX
#0000CD
RGB
rgb(0, 0, 205)
CMYK
cmyk(100%, 100%, 0%, 20%)
HSL
hsl(240, 100%, 40%)
LAB
lab(25.0, 67.2, -91.5)
What is Blue3?
Blue3 is the blue3 reference in the X11 named colors. Its sRGB value is #0000CD (rgb 0, 0, 205). It sits in the blue family. Historical X Window System color names — the numbered 1-4 lightness variants of the classic xorg-server rgb.txt palette. See disclaimer for accuracy and trademark notes.
Accessibility
WCAG 2.1 contrast checks for Blue3 as a background.
Black text on this color
White text on this color
Shades, tints & tonal scale of Blue3
An 11-step tonal scale derived from Blue3 (#0000CD). Click any swatch to copy its HEX. Use these as a starting point for design tokens, hover states, and disabled states in a design system.
50
#EBEBFB
#EBEBFB
100
#D6D6F7
#D6D6F7
200
#ADADEF
#ADADEF
300
#8080E6
#8080E6
400
#4040DA
#4040DA
500
#0000CD
#0000CD
600
#0000AE
#0000AE
700
#000085
#000085
800
#00005C
#00005C
900
#000033
#000033
950
#000019
#000019
Lighter tints (mixed with white)
15%
#6C6CD6
30%
#9595DE
45%
#B3B3E5
60%
#CBCBED
75%
#E1E1F4
Darker shades (mixed with black)
15%
#0000BF
30%
#0000AF
45%
#00009D
60%
#000087
75%
#00006D
Color harmonies for Blue3
Classic color-theory harmonies derived from rotating the hue of Blue3. Use these to build accent palettes, brand systems, and accessible UI color pairings.
Complementary
180° opposite — strongest contrast
#0000CD
#0000CD
#CCCC00
#CCCC00
Triadic
Three colors 120° apart
#0000CD
#0000CD
#CC0000
#CC0000
#00CC00
#00CC00
Analogous
Two neighbors ±30° on the wheel
#0066CC
#0066CC
#0000CD
#0000CD
#6600CC
#6600CC
Split-complementary
Base + two colors flanking its complement
#0000CD
#0000CD
#CC6600
#CC6600
#66CC00
#66CC00
Tetradic
Two complementary pairs
#0000CD
#0000CD
#CC00CC
#CC00CC
#CCCC00
#CCCC00
#00CC00
#00CC00
Square
Four colors evenly spaced 90° apart
#0000CD
#0000CD
#CC0066
#CC0066
#CCCC00
#CCCC00
#00CC66
#00CC66
Blue3 in every color space
Full conversion of Blue3 across the color spaces designers and developers actually use — including OKLCH (the perceptually-uniform space that powers Tailwind v4 and CSS Color Module Level 4) and HWB.
HEX
#0000CD
RGB
rgb(0, 0, 205)
CMYK
cmyk(100%, 100%, 0%, 20%)
HSL
hsl(240, 100%, 40%)
HSV
hsv(240, 100%, 80%)
HWB
hwb(240 0% 20%)
CIE Lab
lab(25.0 67.2 -91.5)
OKLCH
oklch(38.3% 0.266 264.1)
XYZ (D65)
xyz(11.02, 4.41, 58.02)
Copy-ready code for Blue3
Drop-in snippets for CSS, Tailwind, Sass, iOS Swift, and Android XML. Click the copy button on any snippet to put it on your clipboard.
CSS
color: #0000CD;
background-color: #0000CD;CSS variable
:root {
--color-blue3: #0000CD;
}Tailwind config
// tailwind.config.js
colors: {
'blue3': '#0000CD',
}Sass
$color-blue3: #0000CD;Swift UIColor
UIColor(red: 0.000, green: 0.000, blue: 0.804, alpha: 1.0)Android XML
<color name="blue3">#0000CD</color>Closest match in every color system
The nearest Blue3 equivalent in every other color system on this site, ranked by ΔE2000 perceptual distance. Useful when translating between design-system, web-standard, and industrial color references.
Closest in X11 named colors
Top 6 ΔE2000-closest entries within the same collection.
Closest Pantone matches
Top 6 ΔE2000-closest Pantone references. Cross-system matching is approximate — see disclaimer.
Closest RAL Classic matches
Top 6 ΔE2000-closest RAL Classic references for industrial coating cross-reference.
RAL 5005
#1E2460
Signal blue
RAL 5020
#1D334A
Ocean blue
RAL 5017
#063971
Traffic blue
RAL 5000
#354D73
Violet blue
RAL 5010
#0E294B
Gentian blue
RAL 5002
#20214F
Ultramarine blue
FAQ about Blue3
What is the HEX code for Blue3?
Blue3 (blue3) has the HEX code #0000CD. In RGB it is rgb(0, 0, 205), and in CMYK it is cmyk(100%, 100%, 0%, 20%).
What is the OKLCH value of Blue3?
Blue3 converts to oklch(0.383 0.266 264.1). OKLCH is the perceptually uniform color space used by Tailwind v4 and CSS Color Module Level 4.
Is Blue3 accessible for body text?
Used as a background, Blue3 has a contrast ratio of 1.88:1 with black text and 11.16:1 with white text. WCAG 2.1 AA requires 4.5:1 for normal text. The current recommendation is to use white text and verify in real UI context.
What is the closest Pantone to Blue3?
The closest Pantone reference to Blue3 by ΔE2000 perceptual distance is Pantone Blue 072 C (#10069F). Cross-system Pantone matching is approximate; for color-critical print work, verify with a physical Pantone guide.
What is the closest RAL color to Blue3?
The closest RAL Classic reference to Blue3 by ΔE2000 distance is RAL 5005 (Signal blue, #1E2460). RAL is a German industrial coating standard commonly used for paint, powder coat, and architectural specification.
What is the complementary color of Blue3?
The complementary color (180° opposite on the HSL color wheel) of Blue3 is #CCCC00. Use it for high-contrast accents, error states, or call-to-action pairings.
Data provenance & source
X11 named colors (xorg rgb.txt)
The historical X11 color name list shipped in the xorg-server rgb.txt file. Roughly 550 entries covering classic computing color names like 'PapayaWhip', 'MediumAquamarine', and 'DarkSlateGray'. Many CSS named colors originate here. Use as a reference for legacy and creative color names. Most modern CSS implementations accept these names directly.
- Source type
- derived
- Confidence
- high
- License
- MIT/X11 license (X Consortium)
- Last reviewed
- 2026-05-24
Workflow tags
X11 colors are sRGB digital values from a 1980s color system. For print, convert to a process-appropriate color and proof against substrate.