Steelblue1
steelblue1 · #63B8FF
HEX
#63B8FF
RGB
rgb(99, 184, 255)
CMYK
cmyk(61%, 28%, 0%, 0%)
HSL
hsl(207, 100%, 69%)
LAB
lab(72.3, -5.0, -42.8)
What is Steelblue1?
Steelblue1 is the steelblue1 reference in the X11 named colors. Its sRGB value is #63B8FF (rgb 99, 184, 255). 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 Steelblue1 as a background.
Black text on this color
White text on this color
Shades, tints & tonal scale of Steelblue1
An 11-step tonal scale derived from Steelblue1 (#63B8FF). 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
#F3F9FF
#F3F9FF
100
#E6F4FF
#E6F4FF
200
#CDE8FF
#CDE8FF
300
#B1DCFF
#B1DCFF
400
#8ACAFF
#8ACAFF
500
#63B8FF
#63B8FF
600
#549CD9
#549CD9
700
#4078A6
#4078A6
800
#2D5373
#2D5373
900
#192E40
#192E40
950
#0C161F
#0C161F
Lighter tints (mixed with white)
15%
#8AC5FF
30%
#A7D1FF
45%
#BFDCFF
60%
#D3E6FF
75%
#E5F0FF
Darker shades (mixed with black)
15%
#5CABED
30%
#539DDA
45%
#4A8CC4
60%
#3F79AA
75%
#316189
Color harmonies for Steelblue1
Classic color-theory harmonies derived from rotating the hue of Steelblue1. Use these to build accent palettes, brand systems, and accessible UI color pairings.
Complementary
180° opposite — strongest contrast
#63B8FF
#63B8FF
#FFA861
#FFA861
Triadic
Three colors 120° apart
#63B8FF
#63B8FF
#FF61B8
#FF61B8
#B8FF61
#B8FF61
Analogous
Two neighbors ±30° on the wheel
#61FFF7
#61FFF7
#63B8FF
#63B8FF
#6169FF
#6169FF
Split-complementary
Base + two colors flanking its complement
#63B8FF
#63B8FF
#FF6169
#FF6169
#FFF761
#FFF761
Tetradic
Two complementary pairs
#63B8FF
#63B8FF
#A861FF
#A861FF
#FFA861
#FFA861
#B8FF61
#B8FF61
Square
Four colors evenly spaced 90° apart
#63B8FF
#63B8FF
#F761FF
#F761FF
#FFA861
#FFA861
#69FF61
#69FF61
Steelblue1 in every color space
Full conversion of Steelblue1 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
#63B8FF
RGB
rgb(99, 184, 255)
CMYK
cmyk(61%, 28%, 0%, 0%)
HSL
hsl(207, 100%, 69%)
HSV
hsv(207, 61%, 100%)
HWB
hwb(207 39% 0%)
CIE Lab
lab(72.3 -5.0 -42.8)
OKLCH
oklch(75.9% 0.132 245.9)
XYZ (D65)
xyz(40.33, 44.15, 100.98)
Copy-ready code for Steelblue1
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: #63B8FF;
background-color: #63B8FF;CSS variable
:root {
--color-steelblue1: #63B8FF;
}Tailwind config
// tailwind.config.js
colors: {
'steelblue1': '#63B8FF',
}Sass
$color-steelblue1: #63B8FF;Swift UIColor
UIColor(red: 0.388, green: 0.722, blue: 1.000, alpha: 1.0)Android XML
<color name="steelblue1">#63B8FF</color>Closest match in every color system
The nearest Steelblue1 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 5012
#3B83BD
Light blue
RAL 7001
#8F999F
Silver grey
RAL 7040
#9DA1AA
Window grey
RAL 7000
#7E8B92
Squirrel grey
RAL 7004
#9EA0A1
Signal grey
RAL 9006
#A5A5A5
White aluminium
FAQ about Steelblue1
What is the HEX code for Steelblue1?
Steelblue1 (steelblue1) has the HEX code #63B8FF. In RGB it is rgb(99, 184, 255), and in CMYK it is cmyk(61%, 28%, 0%, 0%).
What is the OKLCH value of Steelblue1?
Steelblue1 converts to oklch(0.759 0.132 245.9). OKLCH is the perceptually uniform color space used by Tailwind v4 and CSS Color Module Level 4.
Is Steelblue1 accessible for body text?
Used as a background, Steelblue1 has a contrast ratio of 9.83:1 with black text and 2.14:1 with white text. WCAG 2.1 AA requires 4.5:1 for normal text. The current recommendation is to use black text and verify in real UI context.
What is the closest Pantone to Steelblue1?
The closest Pantone reference to Steelblue1 by ΔE2000 perceptual distance is Pantone 292 C (#69B3E7). Cross-system Pantone matching is approximate; for color-critical print work, verify with a physical Pantone guide.
What is the closest RAL color to Steelblue1?
The closest RAL Classic reference to Steelblue1 by ΔE2000 distance is RAL 5012 (Light blue, #3B83BD). RAL is a German industrial coating standard commonly used for paint, powder coat, and architectural specification.
What is the complementary color of Steelblue1?
The complementary color (180° opposite on the HSL color wheel) of Steelblue1 is #FFA861. 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.