Conversions, palettes, contrast & design ideas for this color.
Color profile
#243B3E is a cool color from the Cyan family, closest in name to “Royal Neptune”. In RGB it is rgb(36, 59, 62); in HSL, hsl(187, 27%, 19%).
The color Royal Neptune, with hexadecimal code #243b3e, is categorized under the cyan family—a cool, refreshing hue fundamental to CMYK printing. Cyan evokes clarity, focus, and digital innovation, appearing across tech interfaces and futuristic design systems. Additionally, it evokes emotions such as Trust, Peace, Loyalty, Integrity and Tranquility. Cyan or blue-green is associated with healing, water, and tranquility. It can symbolize communication and clarity in various cultures. At just 27% saturation, this near-neutral shade carries only a subtle hint of its underlying hue, making it versatile for large surfaces and professional contexts. At only 19% lightness, this extremely dark shade approaches black, delivering maximum drama and contrast when paired with lighter elements. This color is ideal for designs that aim to express Trust, Peace, Loyalty, Integrity, or Tranquility. It can be effectively used in web design, branding, and marketing materials to attract attention and convey specific messages.
Key facts
The story of this color
Royal Neptune (#243B3E) belongs to the Cyan color family.
With a dusty, low-saturation character, this color offers quiet complexity—neither bold nor faded. Dusty tones add vintage charm to retro-inspired designs and pair beautifully with metallic accents like copper or brass.
Cyan is one of the four foundational inks in CMYK printing, making it literally indispensable to modern publishing. The name derives from the Greek kyanos, meaning 'dark blue,' though the color we call cyan today is distinctly lighter. Ancient Egyptian blue—one of the earliest synthetic pigments (c. 2200 BC)—was close to cyan and used extensively in tomb paintings and pottery across the Nile Valley.
Cyan projects a high-tech, digital-forward identity and pairs naturally with white for clean interfaces or with magenta for vibrant contrast. It works well for SaaS products, data-visualization tools, and creative agencies. Use cyan sparingly on warm-toned palettes, as it can feel cold in those contexts.
Sitting on the cool side of the spectrum (hue 187°), it promotes a feeling of calm distance and intellectual clarity, which is why cool hues dominate corporate identities, healthcare design, and productivity tools. At 27% saturation, the color has a muted, sophisticated quality that pairs well with bolder accents. It works as a background, a border, or a secondary element in layered compositions.
Cyan stimulates mental clarity, focus, and communication. It feels refreshing—like a splash of cool water—making it ideal for apps and services centered on productivity, learning, or wellness. Cyan also carries associations with futurism and digital innovation.
Its low lightness of 19% gives it a deep, intense presence. Deep tones like this excel as dark-mode backgrounds, header bars, and anywhere a sense of gravity or luxury is desired.
Build a dark-mode interface with cyan accent elements (buttons, links, progress indicators) on a charcoal background for a sleek developer-tool aesthetic. Use cyan-to-blue gradients in header sections for SaaS landing pages. In print, spot-color cyan on uncoated paper stock creates a tactile, modern feel.
Every format
Every way to write Royal Neptune — one-tap copy on every format; tap on any card to learn what it is and when to use it.
#243B3E
Hexadecimal is the web’s universal color notation — two digits each for red, green and blue. Drop it straight into HTML, CSS or any design tool.
rgb(36, 59, 62)
RGB is the additive Red-Green-Blue model every screen uses to emit light. The default choice for websites, apps and on-screen UI.
hsl(187, 27%, 19%)
HSL breaks a color into Hue, Saturation and Lightness — the most intuitive way to lighten, darken or mute a color in CSS.
hsv(187, 42%, 24%)
HSV (also called HSB) maps Hue, Saturation and Value/Brightness. It is the model behind the color pickers in Photoshop, Figma and most design apps.
hwb(187 14% 76%)
HWB blends a pure hue with Whiteness and Blackness — a painter-friendly model added in CSS Color 4 for quick tints and shades.
cmyk(42%, 5%, 0%, 76%)
CMYK is the subtractive Cyan-Magenta-Yellow-Black ink model. Use these values when preparing artwork for a printer or commercial press.
oklch(33.46% 0.029 206.23)
OKLCH is a modern, perceptually-uniform space (Lightness, Chroma, Hue). It powers smooth gradients and accessible palettes in today’s CSS.
oklab(33.46% -0.026 -0.013)
OKLab is the Cartesian form of OKLCH — ideal for blending and interpolating colors without the muddy midpoints older spaces produce.
L: 23.17, a: -8.05, b: -4.72
CIELAB is a device-independent, perceptually-uniform space. It is the standard for measuring color difference (ΔE) and matching across devices.
L: 23.17, C: 9.33, H: 210.36
LCH is CIELAB in cylindrical form — Lightness, Chroma and Hue — letting you adjust vividness and hue while staying perceptually even.
X: 3.16, Y: 3.85, Z: 5.13
CIE XYZ is the 1931 master space that underpins every other model here — the scientific bridge used to convert between color systems.
2374462
The 24-bit integer value of the color — handy for databases, APIs, game engines and low-level graphics code.
Channel breakdown
How much red, green and blue light mixes into Royal Neptune.
Percentages show each channel's share of the total light (R + G + B) in Royal Neptune.
Ink coverage
Ink needed to reproduce Royal Neptune in four-color print. Heaviest ink: Key (Black).
Print tip: treat these values as a starting point — final output depends on printer profile, paper stock and calibration.
Accessibility · WCAG
How bright Royal Neptune is, and how far black and white text clear each WCAG bar.
Contrast ratio · 1:1 → 21:1 (log scale)
Developer shortcuts
Copy-and-paste CSS for Royal Neptune — per-line copy, or grab the whole block.
background-color: #243B3E;
color: #243B3E;
border: 2px solid #243B3E;
background-color: rgb(36, 59, 62);
background-color: hsl(187, 27%, 19%);
--color: #243B3E;
Shades · light to dark
Lighter and darker steps of Royal Neptune — the color's full brightness range in one strip.
The dot marks the original color. Hover any shade to copy its hex or open its color page.
Harmony · 180° apart
Two colors opposite on the wheel — maximum contrast for attention-grabbing accents.
The dot marks the original color. Hover any shade to copy its hex or open its color page.
Harmony · adjacent hues
Neighboring hues on the wheel — harmonious, calm combinations that feel unified.
The dot marks the original color. Hover any shade to copy its hex or open its color page.
Harmony · 120° apart
Three colors evenly spaced on the wheel — vibrant and energetic, yet balanced.
The dot marks the original color. Hover any shade to copy its hex or open its color page.
Harmony · 90° apart
Four colors evenly spaced on the wheel (tetradic) — rich schemes with multiple accents.
The dot marks the original color. Hover any shade to copy its hex or open its color page.
Accessibility
How Royal Neptune reads across five kinds of color vision — a ✓ Friendly verdict means the color difference stays distinguishable for that vision type.
The dot marks the original color. Hover any shade to copy its hex.
Harmony overview
The lead color from each harmony scheme, side by side — a shortcut to the full palettes above.
Perceptually nearby
A step away in brightness, richness or shade — each still feels like the same color.
From the color-name library
The closest named colors to #243B3E — same mood, each with its own character.
Looking for more Cyan shades? Browse Cyan colors →
Inspiration
Curated Unsplash photos that carry the mood of Royal Neptune — hover any tile to download it or view the original.
Good to know
Harmony