Duke Blue color code: #00009C
A pure-channel deep blue with no red or green contribution beyond the blue axis.
Duke Blue · rgb(0, 0, 156)
Every format for Duke Blue
- HEX
- #00009C
- RGB
- rgb(0, 0, 156)
- HSL
- hsl(240, 100%, 31%)
- HSV
- 240°, 100%, 61%
- CMYK
- 100%, 100%, 0%, 39%
- Lightness
- 31% · mid-tone
Hue sits at 240°, which makes Duke Blue a true blue navy, with 100% saturation. In the Royal Navy family it reads as a mid-tone option.
Text contrast on Duke Blue
Contrast ratios are calculated using the WCAG 2.1 relative luminance formula. Normal body text needs 4.5:1 and large text needs 3:1 to pass AA.
White text on Duke Blue
The quick brown fox jumps over the lazy dog.
14.19:1 — AAA for normal textBlack text on Duke Blue
The quick brown fox jumps over the lazy dog.
1.48:1 — below AA, decorative use onlyDuke Blue text on white
The quick brown fox jumps over the lazy dog.
14.19:1 — AAA for normal textAccessibility notes
- Pair Duke Blue with white text for the strongest reading experience: that combination gives 14.19:1.
- Used as a text colour on white, it clears the 3:1 bar for large headings.
- Never rely on Duke Blue alone to communicate state. Add an icon, label or underline so the meaning survives for colour-blind users and in greyscale printing.
- When placing text over a photograph tinted with Duke Blue, add a solid overlay first. Contrast measured against a flat colour does not hold over varying imagery.
Using Duke Blue in CSS and HTML
CSS example
:root {
--duke-blue: #00009C;
}
.panel {
background-color: var(--duke-blue);
color: #FFFFFF;
border: 1px solid #00009C;
}HTML example
<div style="background-color: #00009C; color: #FFFFFF; padding: 1rem;">
Duke Blue #00009C
</div>Common uses
- Primary buttons, active navigation states and chart series.
- Royal Navy palettes for brand systems that need a dependable cool anchor.
- Print work where a deep blue is preferred to black, using the CMYK build 100%, 100%, 0%, 39%.
- Data visualisation, as one step in a lightness-based navy scale.
Design recommendations
- Build lighter and darker variants by changing only the lightness in
hsl(240, 100%, 31%). Keeping hue fixed is what makes a scale look intentional. - Give Duke Blue at least one warm counterweight. A cool palette with no warm accent tends to read as cold rather than calm.
- Saturation is high here, so use it in measured amounts. Large flat areas of a saturated navy can feel heavy on screen.
Complementary and matching colors
Each of these is derived from the hue, saturation and lightness of Duke Blue. Click a swatch to copy it.
Similar navy shades
Continue exploring
FAQs about Duke Blue
What is the Duke Blue color code?
The Duke Blue color code is #00009C in HEX, rgb(0, 0, 156) in RGB and hsl(240, 100%, 31%) in HSL.
What is the RGB value of Duke Blue?
Duke Blue is rgb(0, 0, 156), meaning 0 units of red, 0 of green and 156 of blue on the 0 to 255 scale.
What is the CMYK value of Duke Blue?
In CMYK, Duke Blue converts to approximately 100%, 100%, 0%, 39%. Printed output will look slightly less saturated than the screen preview because CMYK covers a narrower gamut.
Does white text work on Duke Blue?
White text on Duke Blue gives a contrast ratio of 14.19:1, which is AAA for normal text.
Does black text work on Duke Blue?
Black text on Duke Blue gives a contrast ratio of 1.48:1, which is below AA, decorative use only.
Which colors go with Duke Blue?
Its direct complement is #FAFA00, and the warm accent #BAE43F works well for calls to action. For a quieter scheme, pair it with the analogous blues listed above.
Is Duke Blue a light or dark navy?
At 31% lightness, Duke Blue is classed as a mid-tone navy in this collection.