Conversions, palettes, contrast & design ideas for this color.
Color profile
#ACA9BD is a cool color from the Blue family, closest in name to “Nebulous December”. In RGB it is rgb(172, 169, 189); in HSL, hsl(249, 13%, 70%).
The color Nebulous December, with hexadecimal code #aca9bd, belongs to the blue color family, the world's most universally preferred hue. Blue projects trust, stability, and intellectual calm, which is why it dominates corporate, financial, and technology branding worldwide. Additionally, it evokes emotions such as Softness, Delicacy, Calmness, Relaxation and Friendliness. Blue signifies tranquility and stability. In Middle Eastern cultures, it can also represent protection against the evil eye, while in Western cultures, it symbolizes calmness and reliability. At just 13% saturation, this near-neutral shade carries only a subtle hint of its underlying hue, making it versatile for large surfaces and professional contexts. At 70% lightness, it strikes an approachable, open balance—bright enough to feel welcoming yet substantial enough to carry visual weight. This color is ideal for designs that aim to express Softness, Delicacy, Calmness, Relaxation, or Friendliness. 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
Nebulous December (#ACA9BD) belongs to the Blue 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.
Blue's scarcity in nature made it a late addition to human color vocabulary—Homer's 'wine-dark sea' notably omits the word blue entirely. The breakthrough came with Egyptian Blue (~2200 BC) and later ultramarine from Afghan lapis lazuli, which Medieval artists hoarded for divine subjects. Synthetic ultramarine (1826) and cobalt blue democratized the color, enabling Impressionists like Monet and Renoir to paint blue-drenched landscapes affordably.
Blue is the most universally liked color and dominates corporate branding (Facebook, LinkedIn, IBM, Samsung). Use it to establish trust, competence, and professionalism. Lighter blues suit wellness and social apps, while darker blues convey authority and security. Avoid using blue for food branding—it suppresses appetite.
Sitting on the cool side of the spectrum (hue 249°), it promotes a feeling of calm distance and intellectual clarity, which is why cool hues dominate corporate identities, healthcare design, and productivity tools. With only 13% saturation, this near-neutral shade carries just a hint of its underlying hue—subtle enough for large surfaces yet adding more warmth (or coolness) than a pure gray.
Blue lowers blood pressure and heart rate, promoting calm and focused thought. It signals reliability and integrity, which is why it is the default choice for banks, insurance companies, and government institutions. In UX, blue links and buttons feel intuitive because users have been trained by decades of web convention.
At 70% lightness, it reads clearly on dark backgrounds and provides a welcoming, open feel in light-themed designs—versatile across both contexts.
Pair classic blue (#0047AB) with warm amber for a nautical or heritage brand. Use gradient blues (light-to-dark, top-to-bottom) for app onboarding screens that feel expansive and inviting. In data dashboards, blue is the safest primary chart color—it's distinct, professional, and colorblind-friendly.
Every format
Every way to write Nebulous December — one-tap copy on every format; tap on any card to learn what it is and when to use it.
#ACA9BD
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(172, 169, 189)
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(249, 13%, 70%)
HSL breaks a color into Hue, Saturation and Lightness — the most intuitive way to lighten, darken or mute a color in CSS.
hsv(249, 11%, 74%)
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(249 66% 26%)
HWB blends a pure hue with Whiteness and Blackness — a painter-friendly model added in CSS Color 4 for quick tints and shades.
cmyk(9%, 11%, 0%, 26%)
CMYK is the subtractive Cyan-Magenta-Yellow-Black ink model. Use these values when preparing artwork for a printer or commercial press.
oklch(74.37% 0.029 292.58)
OKLCH is a modern, perceptually-uniform space (Lightness, Chroma, Hue). It powers smooth gradients and accessible palettes in today’s CSS.
oklab(74.37% 0.011 -0.026)
OKLab is the Cartesian form of OKLCH — ideal for blending and interpolating colors without the muddy midpoints older spaces produce.
L: 70.05, a: 4.99, b: -9.84
CIELAB is a device-independent, perceptually-uniform space. It is the standard for measuring color difference (ΔE) and matching across devices.
L: 70.05, C: 11.04, H: 296.89
LCH is CIELAB in cylindrical form — Lightness, Chroma and Hue — letting you adjust vividness and hue while staying perceptually even.
X: 40.39, Y: 40.82, Z: 53.89
CIE XYZ is the 1931 master space that underpins every other model here — the scientific bridge used to convert between color systems.
11315645
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 Nebulous December.
Percentages show each channel's share of the total light (R + G + B) in Nebulous December.
Ink coverage
Ink needed to reproduce Nebulous December 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 Nebulous December 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 Nebulous December — per-line copy, or grab the whole block.
background-color: #ACA9BD;
color: #ACA9BD;
border: 2px solid #ACA9BD;
background-color: rgb(172, 169, 189);
background-color: hsl(249, 13%, 70%);
--color: #ACA9BD;
Shades · light to dark
Lighter and darker steps of Nebulous December — 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 Nebulous December 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 #ACA9BD — same mood, each with its own character.
Looking for more Blue shades? Browse Blue colors →
Inspiration
Curated Unsplash photos that carry the mood of Nebulous December — hover any tile to download it or view the original.
Good to know
Harmony