Tints & Shades
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Scale from white (50) through Duke Blue (500) to black (900), interpolated in Lab color space.
Color Values
- HEX
- #00009C
- RGB
- rgb(0, 0, 156)
- HSL
- hsl(240, 100%, 31%)
- OKLCH
- oklch(0.313 0.217 264)
- CMYK
- cmyk(100%, 100%, 0%, 39%)
--color-duke-bluebg-[#00009C]Accessibility
Score: 96/100On White (#FFF)
14.19:1
On Black (#000)
1.48:1
On Light Gray (#F5F5F5)
13.01:1
Best text color on this background:
Design Applications
background-color: #00009C
color: #00009C
bg-[#00009C] text-[#FFFFFF]
border-left: 4px solid #00009C
Color Harmonies
Similar Colors
Color Meaning & Psychology
Blue is the world's most universally preferred color across cultures. It slows respiration, lowers blood pressure, and promotes calm — the physiological opposite of red. Blue's associations with sky and water make it feel limitless, trustworthy, and reliable. In corporate design, blue dominates banking, insurance, healthcare, and technology precisely because it communicates stability. Dark navy conveys authority and tradition; royal blues suggest quality and aspiration; sky blues feel open and optimistic; teal bridges trust with modernity. The primary limitation of blue is food — it suppresses appetite, with almost no naturally blue foods existing in nature. Its deeper, richer tone gives it gravitas and sophistication, making it well-suited for primary brand colors, typography, and contexts where authority matters.
Industry Usage
Common contexts and industries where Duke Blue is applied in professional design.
- Banking, insurance, and financial institutions
- Healthcare and medical device companies
- Enterprise software and SaaS platforms
- Government and public sector organizations
- Airlines and aviation brands
- Communication and social networking apps
- Cybersecurity and data protection products
- Pharmaceutical companies and clinical products
Accessibility Considerations
Normal Text
Passes AA
4.5:1 minimum required
Large Text
Passes AA Large
3:1 minimum required
UI Components
Meets 1.4.11
3:1 for non-text UI
Duke Blue is a dark color. Use white (#FFFFFF) text on top of it for maximum readability (14.19:1). Avoid small black text on this background.
CSS & Code Examples
Background
background-color: #00009C;Text
color: #00009C;Border
border: 2px solid #00009C;Box Shadow
box-shadow: 0 4px 20px #00009C40;Gradient
background: linear-gradient(135deg, #00009C, #5532ce);Tailwind-style
--color-duke-blue: #00009C;Tailwind CSS Utilities
Use arbitrary value syntax in Tailwind CSS to apply Duke Blue without a custom config.
Background
bg-[#00009C]Text
text-[#00009C]Border
border-[#00009C]Ring
ring-[#00009C]Fill
fill-[#00009C]From (gradient)
from-[#00009C]Via (gradient)
via-[#00009C]To (gradient)
to-[#00009C]Design Tokens
Ready-to-use Duke Blue design token in CSS custom properties, SCSS, Tailwind v3/v4, and JSON formats.
CSS Custom Properties
:root {
--color-duke-blue: #00009C;
--color-duke-blue-rgb: 0, 0, 156;
--color-duke-blue-hsl: 240, 100%, 31%;
}SCSS Variables
$color-duke-blue: #00009C; $color-duke-blue-rgb: 0, 0, 156; $color-duke-blue-hsl: 240, 100%, 31%;
Tailwind v3 Config
// tailwind.config.js
module.exports = {
theme: {
extend: {
colors: {
'duke-blue': '#00009C',
},
},
},
};Tailwind v4 (@theme)
/* tailwind.css */
@theme {
--color-duke-blue: #00009C;
}JSON Design Token (W3C format)
{
"duke-blue": {
"value": "#00009C",
"type": "color",
"description": "Duke Blue — #00009C"
}
}More blue colors
View all →What Does Duke Blue Mean? Color Psychology & Cultural Symbolism
Duke Blue at #00009C is a deep expression of the trust spectrum. Blue tones are processed by the brain's credibility centers before conscious evaluation—which is why virtually every major financial institution, technology company, and government body defaults to the blue family to establish authority.
- Across color psychology research, blue consistently tests high for "trustworthiness" associations, making Duke Blue a reliable vehicle for trust in cross-demographic audiences.
- Brand designers draw on blue-family tones to project stability and competence—values that Duke Blue communicates in a deep key.
- At 100% saturation, Duke Blue reads as vivid—Electric and royal blues are modern, confident, and digitally native—they signal tech-forward positioning and work well for startups challenging traditional industries.
- Duke Blue's deep lightness (31%) shifts its psychological register: Navy and deep blues project gravitas, authority, and executive-level trust—the dominant choice for financial services, law firms, and premium B2B brands.
The power of Duke Blue is quiet consistency. It builds trust cumulatively, appearing wherever credibility matters.
How to Use Duke Blue in Design: Applications, Pairings & Best Practices
The design challenge with Duke Blue is differentiation: every major institution uses blue. The answer lies in tone, proportion, and pairing—how a specific blue is used matters more than whether it's used.
- Avoid: food contexts where it suppresses appetite (the only major color with no natural blue foods), extreme urgency signals, and applications targeting very young children where warmer colors perform better.
- Color harmonies: Duke Blue's complementary color creates a high-energy split ideal for promotional design; its analogous palette (±30° hue) builds cohesive, monochromatic sophistication.
- Proportional use: Duke Blue's vivid saturation (100%) means small applications—accents, highlights, icons—deliver maximum impact without visual fatigue. Reserve large-scale use for intentional brand moments.
- As a dark tone, Duke Blue creates maximum contrast with white and light neutrals—excellent for creating premium dark-mode sections, bold headers, and high-drama brand moments
- Typography: Duke Blue works as a background behind white text but requires careful sizing—test at intended heading and body sizes before finalizing.
The power of Duke Blue is quiet consistency. It builds trust cumulatively, appearing wherever credibility matters.
Duke Blue Accessibility: WCAG Contrast Ratios, Color Blindness & Inclusive Design
Duke Blue (#00009C) achieves a 14.19:1 contrast ratio with white text, surpassing the WCAG 2.1 AAA threshold of 7:1. This exceptional contrast qualifies it for body text, UI components at any size, and all accessibility-sensitive interface contexts. Relative luminance: 2.4%.
- As text on white (#FFFFFF): 14.19:1 — AAA ✓
- As text on black (#000000): 1.48:1 — Fail
- Best text color on Duke Blue background: White (#FFFFFF) at 14.19:1
- WCAG 2.1 luminance: 2.4% — low luminance (dark)—it provides strong contrast for white and light overlaid text, functioning well as a background in dark-mode and header contexts
- Duke Blue qualifies for all text sizes including small body copy (AAA).
- Color blindness consideration: tritanopia (blue-yellow color blindness, ~0.003% of population) may affect how this color reads. While rare, for maximum accessibility supplement color signals with text or icon indicators in critical states.
For production use, test Duke Blue against your specific background colors rather than assuming #FFFFFF or #000000 performance translates. Surrounding colors alter perceived contrast.
Duke Blue in Industry: Branding, Design & Market Applications
Duke Blue's brand positioning falls squarely in the territory of trust, reliability, calm, and professionalism. Industry data supports its strongest performance in finance, technology, healthcare categories, where the vivid saturation calibrates the message at a deep, considered level.
- Finance & Banking: Blue is the most trusted color in financial services—a global design convention built over decades. It signals fiduciary reliability, stability, and the conservative stewardship that depositors and investors need to feel comfortable transferring wealth. (examples: Capital One, PayPal, Visa) Dark navy communicates established tradition; mid-tone blues suggest accessible, modern banking. Avoid pure bright blue for legacy institutions.
- Technology: Technology brands use blue to communicate intelligence, reliability, and forward-thinking professionalism. From legacy enterprise software to consumer apps, blue provides a neutral credibility that scales across markets and cultures. (examples: Apple, Microsoft, Salesforce) Varying the tone of blue is how tech brands differentiate: sky blue for friendliness (consumer apps), royal blue for confidence (productivity tools), navy for enterprise seriousness.
- Healthcare: Healthcare's use of blue is a trust transfer from corporate credibility to clinical reliability. Patients associate blue with cleanliness, precision, and medical competence—making it the second most common healthcare color after white. (examples: Headspace, One Medical, Kaiser Permanente) Teal-blue works particularly well for health tech and telemedicine, balancing clinical trust with digital accessibility.
- Brand positioning: Duke Blue is best suited for brands projecting trustworthiness, reliability, professionalism. Categories outside this positioning—food contexts where it suppresses appetite (the only major color with no natural blue foods)—tend to see weaker results.
- Adjacent applications: Beyond primary industries, Duke Blue works effectively in corporate identity, banking and finance UIs, healthcare platforms—contexts where stability serves a secondary but reinforcing role.
For marketers and brand strategists, Duke Blue is a commitment to trust, reliability, calm, and professionalism. Match it with industries that make that promise and it will pay dividends consistently.
Accessibility & Design Guides
Frequently Asked Questions
- What is the hex code for Duke Blue? ▾
- The hex code for Duke Blue is #00009C. Its RGB values are rgb(0, 0, 156) and its HSL values are hsl(240, 100%, 31%).
- What does Duke Blue mean in design? ▾
- Blue is the world's most universally preferred color across cultures. It slows respiration, lowers blood pressure, and promotes calm — the physiological opposite of red. Blue's associations with sky and water make it feel limitless, trustworthy, and reliable. In corporate design, blue dominates banking, insurance, healthcare, and technology precisely because it communicates stability. Dark navy conveys authority and tradition; royal blues suggest quality and aspiration; sky blues feel open and optimistic; teal bridges trust with modernity. The primary limitation of blue is food — it suppresses appetite, with almost no naturally blue foods existing in nature. Its deeper, richer tone gives it gravitas and sophistication, making it well-suited for primary brand colors, typography, and contexts where authority matters.
- Is Duke Blue WCAG accessible? ▾
- Duke Blue (#00009C) passes WCAG AAA on white with a 14.19:1 contrast ratio. Its overall accessibility score is 96/100.
- What colors go well with Duke Blue? ▾
- Duke Blue pairs well with its complementary color Yellow (#FFFF00). Analogous colors like Bleu de France and Royal Blue also work harmoniously. Check the Color Harmonies section above for the full palette.
- What is Duke Blue used for? ▾
- Duke Blue is commonly used for: Banking, insurance, and financial institutions; Healthcare and medical device companies; Enterprise software and SaaS platforms; Government and public sector organizations; Airlines and aviation brands.
- What are the CSS and Tailwind values for Duke Blue? ▾
- In CSS, use `color: #00009C` or `background-color: #00009C`. The CSS custom property is `--color-duke-blue: #00009C`. In Tailwind CSS, use the arbitrary value class `bg-[#00009C]` for backgrounds or `text-[#00009C]` for text.