#00378A Color

#00378A is rgb(0, 55, 138) in RGB, hsl(216, 100%, 27%) in HSL, and about cmyk(100%, 60%, 0%, 46%) in CMYK. It has no registered color name of its own — the closest is St. Patrick's Blue (#23297A), clearly related but distinguishable side by side at ΔE 9.31. White text is the more readable choice on this background.

#00378A

HEX#00378A

RGBrgb(0, 55, 138)

HSLhsl(216, 100%, 27%)

HSVhsv(216, 100%, 54%)

CMYKcmyk(100%, 60%, 0%, 46%)

OKLCHoklch(36.4% 0.148 259.9)

LABlab(24.57% 12.89 -51.59)

LCHlch(24.57% 53.17 284.03)

What #00378A Is Called

Most hex codes have no name: there are 16.7 million of them and a few thousand registered names. These are the named colors nearest to #00378A, ordered by CIE76 distance in CIELAB. Anything under about ΔE 2 is a difference most people cannot see.

St. Patrick's Blue#23297AΔE 9.31 Iron Indigo#184FA1ΔE 10.88 Cobalt Blue#0047ABΔE 11.09 Cosmic Cobalt#2E2D88ΔE 11.47 Sapphire Navy#082567ΔE 12.16 Smalt (Dark Powder Blue)#003399ΔE 12.22

Browse the full index of named colors A-Z or every blue in the library.

#00378A Channel Values

How #00378A breaks down in each color model. Hue is measured in degrees around the color wheel; saturation, lightness, and the CMYK inks are percentages.

Model	Channels	Notes
RGB	R 0 · G 55 · B 138	8-bit channels as sent to the display
HSL	H 216° · S 100% · L 27%	Easiest model for building lighter and darker variants
HSV	H 216° · S 100% · V 54%	Matches the picker in most design tools
CMYK	C 100% · M 60% · Y 0% · K 46%	Approximate ink mix; confirm with an ICC profile before printing
Luminance	10.97:1 vs white · 1.91:1 vs black	WCAG 2.2 relative-luminance contrast ratios

Text Contrast & Accessibility

WCAG 2.2 contrast ratios for text on a #00378A background. AA requires 4.5:1 for normal text and 3:1 for large text; AAA requires 7:1. Contrast is one check, not a full accessibility review.

TextWhite text10.97:1AA normal AA large AAA normal

Fails AABlack text1.91:1AA normal AA large AAA normal

Need a specific ratio against another background? Open #00378A in the contrast checker.

Colors That Go With #00378A

Pairings derived from color-wheel relationships. The complementary color sits opposite #00378A; analogous colors sit beside it; triadic and split-complementary sets spread evenly around the wheel. Select any swatch for its own breakdown.

Base

Complementary

Analogous

Analogous

Triadic

Triadic

Split comp.

Split comp.

Tints & Shades of #00378A

Lighter tints and darker shades built by moving the lightness channel while holding hue and saturation, which is what you want for hover states, backgrounds, and text variants.

Tints

Shades

Want a full 50-950 ramp with semantic roles? Generate design tokens from #00378A.

How #00378A Looks with Color Vision Deficiency

Simulated with the Viénot, Brettel & Mollon LMS projection model. Anomalous types are rendered as partial versions of the matching dichromacy, which is an approximation rather than a per-person clinical model.

Typical#00378A

Protanopia#32328A

Protanomaly#26348A

Deuteranopia#2C2C8A

Deuteranomaly#21318A

Tritanopia#004848

Tritanomaly#004269

Achromatopsia#3C3C3C

Test a full palette in the color blindness simulator.

Using #00378A in Code

Copy-ready declarations for the places this color usually ends up.

CSS custom property--color-00378a: #00378A;

CSS backgroundbackground-color: #00378A;

Tailwind configcolors: { 'color-00378a': '#00378A' }

SwiftUIColor(red: 0.000, green: 0.216, blue: 0.541)

Android XML<color name="color_00378a">#00378A</color>

SVG fillfill="#00378A"

More Blue Colors

#00378A sits in the blue family. These are its neighbours across that family's full range, each with its own breakdown.

000024 fafaff 00002e f9fafb 000033 f8fafc 000038 f8f8ff 000042 f5faff 000047 f5f5ff 002147 007dfa 0f52ba 1c39bb 2a3439 372aac 4e3cc3 64609a 7abdff 979aaa b8dbff d6d6ff

#00378A Frequently Asked Questions

What color is #00378A?

#00378A is a dark blue — rgb(0, 55, 138) in RGB and hsl(216, 100%, 27%) in HSL. It carries no registered color name of its own; the closest named color is St. Patrick's Blue (#23297A), which is clearly related but distinguishable side by side at a CIE76 distance of 9.31.

What is the RGB value of #00378A?

#00378A is rgb(0, 55, 138) — red 0, green 55, and blue 138 on the 0-255 scale.

What is the CMYK value of #00378A?

#00378A converts to approximately cmyk(100%, 60%, 0%, 46%). CMYK output is a mathematical approximation for planning; confirm production print colors with your printer and ICC profile.

Should text on #00378A be black or white?

White text is the more readable choice. #00378A scores 10.97:1 against white and 1.91:1 against black, and WCAG 2.2 asks for at least 4.5:1 for normal body text.

Can I write #00378A as a CSS color keyword?

No. #00378A is not one of the CSS color keywords, so it has to be written as a hex, rgb() or hsl() value. The closest keyword is darkslateblue (#483D8B) at a CIE76 distance of 13.55, which is visibly different.

Open #00378A in a Tool

Hex to RGB Hex to HSL Hex to CMYK Hex to OKLCH Hex to Pantone Build a palette Make a gradient

Keep exploring: every blue in the color library, the guide to shades of blue, or the full color library.