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cyan · cool

#04545b

a deep, electric cyan · cool · closest name: Dark Slate Gray

Token name suggestion: Ink Lagoon

RGB
4, 84, 91
HSL
185°, 92%, 19%
CMYK
96, 8, 0, 64
Luminance
0.0712

#04545b is a deep electric cyan, 185° on the wheel and 89/100 on the cool side. Put white text on it (8.66:1). As text it scores 8.66:1 on white — safe at any size. Nearest name is Dark Slate Gray, nearest Tailwind family is slate.

hsl(185 92% 19%)rgb(4 84 91)Base step 950AAA inkCool

At a glance

Every number on this page in one read: what #04545b is made of, how bright it looks, and which way it leans.

Hex
#04545b
Hue
185°
cyan
Saturation
92%
electric
Lightness
19%
deep
Brightness
36%
HSV value
Perceived
28%
weighted brightness
Luminance
0.0712
WCAG relative
Temperature
Cool
89/100 cool
Color family
Cyan
Tone
Electric
Best ink
White
8.66:1
Closest name
Dark Slate Gray
ΔE2000 6.1
Chroma
21.2
LCH, 0–130ish
OKLCH L
0.407
perceptual lightness
Tailwind
slate
500 · ΔE 21.6
Web-safe
#006666
nearest of 216
Where it sits
Hue185° of 360°
Saturation92%
Lightness19%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #04545b.

Temperature
Warm ← → Cool89% cool

Reads cool. Warm and cool siblings keep the same lightness, so you can swap one in without redoing your contrast maths.

Luminance by channel
Red0%
Green89%
Blue11%

Green carries most of what the eye calls brightness — that is why WCAG weights it 0.7152.

Every format

HEX#04545b
HEX (8-digit)#04545bff
RGBrgb(4, 84, 91)
RGBArgba(4, 84, 91, 1)
HSLhsl(185, 92%, 19%)
HSV / HSBhsv(185, 96%, 36%)
HWBhwb(185 2% 64%)
CMYKcmyk(96%, 8%, 0%, 64%)
LABlab(32.1 -18.6 -10.3)
LCHlch(32.1 21.2 208.9)
OKLCHoklch(0.407 0.068 204.8)
XYZ (D65)xyz(5.11, 7.12, 11.00)
Decimal283739
Display P3color(display-p3 0.016 0.329 0.357)
Web-safe#006666

Copy-ready code

every platformclick to select
/* CSS */
color: #04545b;
background-color: #04545b;
/* CSS custom property */
--brand: #04545b;
/* Tailwind (arbitrary) */
class="text-[#04545b] bg-[#04545b]"
/* SCSS */
$brand: #04545b;
/* SwiftUI */
Color(red: 0.016, green: 0.329, blue: 0.357)
/* UIKit */
UIColor(red: 0.016, green: 0.329, blue: 0.357, alpha: 1)
/* Android XML */
<color name="brand">#04545B</color>
/* Android Compose */
Color(0xFF04545B)
/* Flutter */
Color(0xFF04545B)
/* Python / OpenCV (BGR) */
(91, 84, 4)
/* Python / PIL (RGB) */
(4, 84, 91)
/* Java AWT */
new Color(4, 84, 91)
/* .NET */
Color.FromArgb(255, 4, 84, 91)
/* OpenGL / Unity (0–1) */
(0.0157f, 0.3294f, 0.3569f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{4,84,91}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #04545b 85%, white);
border-color: color-mix(in oklab, #04545b 40%, transparent);
/* theme-aware in one line */
color: light-dark(#05717A, #D3ECEE);
/* relative colour syntax */
--hover: hsl(from #04545b h s calc(l - 7));

Design tokens

The same ramp in the four formats a team actually needs. Paste one and the whole palette lands with it.

css custom propertiesclick to select
:root {
  --brand-50: #F2FCFD;
  --brand-100: #E4F9FB;
  --brand-200: #C3F5F9;
  --brand-300: #94F2FA;
  --brand-400: #5EECF8;
  --brand-500: #28E5F6;
  --brand-600: #0AD9EB;
  --brand-700: #09B4C3;
  --brand-800: #07909C;
  --brand-900: #0A6971;
  --brand-950: #04545b;
  --brand: #04545b;
  --brand-ink: #ffffff;
  --brand-surface: #F4FAFA;
  --brand-border: #C0E9ED;
  --brand-hover: #023439;
  --brand-pressed: #011516;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #142324;
    --brand-ink: #D3ECEE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F2FCFD',
        100: '#E4F9FB',
        200: '#C3F5F9',
        300: '#94F2FA',
        400: '#5EECF8',
        500: '#28E5F6',
        600: '#0AD9EB',
        700: '#09B4C3',
        800: '#07909C',
        900: '#0A6971',
        950: '#04545b',
        DEFAULT: '#04545b',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F2FCFD,
  '100': #E4F9FB,
  '200': #C3F5F9,
  '300': #94F2FA,
  '400': #5EECF8,
  '500': #28E5F6,
  '600': #0AD9EB,
  '700': #09B4C3,
  '800': #07909C,
  '900': #0A6971,
  '950': #04545b,
);
$brand-base: #04545b;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F2FCFD", "$type": "color" },
      "100": { "$value": "#E4F9FB", "$type": "color" },
      "200": { "$value": "#C3F5F9", "$type": "color" },
      "300": { "$value": "#94F2FA", "$type": "color" },
      "400": { "$value": "#5EECF8", "$type": "color" },
      "500": { "$value": "#28E5F6", "$type": "color" },
      "600": { "$value": "#0AD9EB", "$type": "color" },
      "700": { "$value": "#09B4C3", "$type": "color" },
      "800": { "$value": "#07909C", "$type": "color" },
      "900": { "$value": "#0A6971", "$type": "color" },
      "950": { "$value": "#04545b", "$type": "color" }
    },
    "brandInk": { "$value": "#ffffff", "$type": "color" }
  }
}

Best text color

Only one of black and white can be right. This is the one, with the number that proves it.

Readable at a glance#ffffff on #04545b · 8.66:1
Use #ffffffAAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 8.66:1 · recommended
AA pass · AA large pass · AAA pass
Aa
Black text · 2.42:1
AA fail · AA large fail · AAA fail
Reading the other direction: #04545b as text scores 8.66:1 on white and 2.42:1 on black.
Best tinted ink on it, if plain black or white feels flat: #E7FCFE at 8.15:1.

Make it accessible

A contrast checker tells you that you failed. This tells you what to ship instead — same hue, same saturation, lightness moved only as far as WCAG demands.

The quick fox
#04545b · 8.66:1
AA on whitealready passes
#04545b
The quick fox
#04545b · 8.66:1
AAA on whitealready passes
#04545b
The quick fox
#06818C · 4.53:1
AA on black+10% L
#06818C
The quick fox
#08A5B3 · 7.04:1
AAA on black+18% L
#08A5B3

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #04545B is enough for headings on white. Non-text elements such as icons, chart strokes and focus rings also sit at 3:1 under WCAG 2.2 (1.4.11).

Accessibility — WCAG contrast

Aa
#04545b on white: 8.66:1
AA ✓ pass · AA-large · AAA
Aa
#04545b on black: 2.42:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #04545b as text on that neutral, and that neutral as text on #04545b.

NeutralRatioBoth directions
White8.66:1AaAa
Slate 508.28:1AaAa
Slate 1007.91:1AaAa
Slate 2007.03:1AaAa
Slate 3005.83:1AaAa
Slate 4003.38:1AaAa
Slate 5001.82:1AaAa
Slate 6001.14:1AaAa
Slate 7001.20:1AaAa
Slate 8001.69:1AaAa
Slate 9002.06:1AaAa
Black2.42:1AaAa
Colour vision deficiency
true color
protanopia · #4C505B
deuteranopia · #41485B
tritanopia · #005856

Roughly one man in twelve has some form of colour vision deficiency. If any of the three panels above is hard to tell apart from a neighbouring colour in your palette, add a shape, an icon or a label so the meaning does not rest on hue alone.

Color scale — 50 to 950

A Tailwind-shaped ramp built around this exact hex. #04545b is pinned to step 950; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F2FCFD
#E4F9FB
#C3F5F9
#94F2FA
#5EECF8
#28E5F6
#0AD9EB
#09B4C3
#07909C
#0A6971
#04545b
Base = 950Lightest = 50 · #F2FCFDDarkest = 950 · #04545bText step on white = 900
Perceptual ramp — OKLCH

The same eleven steps expressed in OKLCH, where equal lightness numbers actually look equally spaced. HSL ramps go muddy in the yellows and washed out in the blues; this one does not. Modern browsers render it natively — the hex ramp above is the fallback.

50100200300400500600700800900950
oklch tokensclick to select
:root {
  --brand-50: oklch(0.97 0.017 204.8);
  --brand-100: oklch(0.94 0.027 204.8);
  --brand-200: oklch(0.88 0.041 204.8);
  --brand-300: oklch(0.80 0.053 204.8);
  --brand-400: oklch(0.72 0.063 204.8);
  --brand-500: oklch(0.64 0.068 204.8);
  --brand-600: oklch(0.56 0.068 204.8);
  --brand-700: oklch(0.48 0.064 204.8);
  --brand-800: oklch(0.40 0.057 204.8);
  --brand-900: oklch(0.32 0.048 204.8);
  --brand-950: oklch(0.24 0.038 204.8);
}

Colors that work with #04545b

Not a palette — a role sheet. Each swatch answers one question you will hit while building the component.

Text on it#ffffff
White wins here
Surface#F4FAFA
Tinted page background
Border#C0E9ED
Hairlines and dividers
Muted text#4B949B
Captions on the surface
Accent#5D0212
Second voice, not a rival
Dark variant#05717A
Hover, pressed, headers
Light variant#E7FCFE
Selected rows, tints
Dark surface#142324
Dark-mode background
Hover#023439
One step down in lightness
Pressed#011516
Two steps down
Disabled#517B7E
Chroma pulled out
Focus ring#006A73
Offset from the fill so it reads
Light mode
Everything in its place

Surface, border, heading and body all derive from this one hue, so the screen stays coherent without a second palette.

Primary actionSecondaryBadge
Dark mode
Same hue, inverted

Lightness flips, hue holds. The accent stays the anchor in both themes.

Primary actionSecondaryAccent

In real components

The same eight roles, wired into the interface patterns you will actually build with them. Every state below is a computed value, not a mock-up.

Buttons and states
Save changesHoverPressedDisabled
OutlineSubtleLinkFocused
Form field
you@company.com

Focus ring uses the light variant so the field still reads as one shape.

Send me product updates
Notice
Your export is ready

The file stays available for seven days. Download it before it expires.

NewBetaDraft
Data
Storage used68%
Acme LtdActive
NorthwindTrial
GlobexActive

How to use #04545b

Derived from its contrast, chroma and lightness — not from taste.

Works well for
  • Body text and links on white
  • Primary buttons and calls to action
  • Focus rings, active and selected states
  • Headers, footers and dark-mode surfaces
  • Brand accents, badges and data highlights
Use with care
  • Text on black or near-black surfaces
  • Full-page backgrounds — tiring over long sessions
  • Black text placed on it
  • Thin strokes and 1px borders — they disappear on light UI
  • Pairing with a same-lightness hue — edges vibrate
Minimum size as text on white
Any size
Safe as a fill behind white type
Yes
Safe as a 1px border on white
Yes

Meaning and mood

What a colour in this family tends to signal, and how this particular chroma and lightness change the reading.

cleantechnicalfreshclinical

Cyan reads as water, air and infrastructure: cool, hygienic, engineered.

At this chroma the association is amplified — it will dominate anything placed beside it, so give it space and use it sparingly. The low lightness adds weight and formality.

Worth knowing

At high lightness it disappears into white surfaces and thin strokes vanish entirely.

Reads as
  • FormalityHigh
  • EnergyHigh
  • Weight81/100
  • TemperatureCool
  • ApproachabilityReserved

Colour associations are cultural and vary by market. Treat these as a starting point for a conversation with your audience, not a finding about them.

Similar colors

One move away from this hex in each direction. Every swatch is its own page.

Color relationships

The wheel positions with their names attached, so you can grab the one you actually need.

Complementary#5B0B04
Analogous left#045B36
Analogous right#04285B
Split-complement 1#5B0428
Split-complement 2#5B3604
Triadic 1#5B0454
Triadic 2#545B04
Tetradic#36045B
On the wheel
Base+30°−30°+120°+240°+180°185°

#04545b sits at 185°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red1.6%
Green32.9%
Blue35.7%
R · 0–255
4
0x04
G · 0–255
84
0x54
B · 0–255
91
0x5b

CMYK percentages

Cyan95.6%
Magenta7.7%
Yellow0.0%
Key (black)64.3%

Total ink coverage is 168%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#04545b text on a black background

contrast 2.42:1

Card sample

#04545b text on a white background

contrast 8.66:1

Card sample

#04545b on grey

7.91:1

#04545b on its own surface

8.21:1

#04545b on its dark surface

1.87:1

CSS3 live lab

Text font color

The quick brown fox

color: #04545b;
Background color
Panel with #04545b background
background-color: #04545b;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #04545b;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(4, 84, 91, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(4, 84, 91, 0.45);
Border & gradient
Gradient panel
border: 3px solid #04545b;
background: linear-gradient(135deg, #04545b, #041A5B);
Gradient text

Gradient headline

background: linear-gradient(90deg, #04545b, #04045B);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #04545b;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #04545b;
caret-color: #04545b;
Left rule
Pull quote or callout
border-left: 4px solid #04545b;
Ring + tint
Selected chip
background: #E7FCFE;
box-shadow: inset 0 0 0 2px #04545b;
Conic badge
68%
background: conic-gradient(#04545b 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #04545b over white; the bottom row is the same alpha over a checkerboard, so you can see what survives on a photo or a video.

Bottom row of hexes is the flattened result over white — use those when a design tool refuses transparency, or when you need a solid fallback.

alpha in every syntaxclick to select
rgba(4, 84, 91, 0.5)
rgb(4 84 91 / 50%)
#04545b80
hsl(185 92% 19% / 50%)
color-mix(in srgb, #04545b 50%, transparent)
Alpha8-digit hexFlat on white
10%#04545b1a#E6EEEF
20%#04545b33#CDDDDE
40%#04545b66#9BBBBD
60%#04545b99#68989D
80%#04545bcc#36767C

Gradients from #04545b

Six recipes, each built from this hex and shown with the exact CSS that produced it.

Elevation
Same hue, three lightnesses — safe anywhere
background: linear-gradient(135deg, #078A96, #04545b 45%, #05717A);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #04545b, #030D3E);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #04545b, #5B0B04);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #08A5B3 0%, #04545b 45%, #05717A 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F4FAFA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #068C48 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #052C78 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #05717A 0%, transparent 65%), #04545b;

Monochromatic scale

Palettes built from #04545b

Shades — darker

Tints — lighter

Tones — desaturated

Color harmonies

Nearest named colors

Ranked with CIEDE2000 across all 139 CSS keywords. Under ΔE 2 the eye stops telling them apart; over ΔE 10 they are plainly different colors.

#04545b in the real world

Where a color in this family tends to land, and the interface roles it is usually asked to play.

Industries
TechnologyTravelHealthcareMedia
Common UI roles
ButtonsLinksFocus statesCharts
Print note

Sits outside most CMYK gamuts — expect a duller press result, or specify a spot ink.

On screens

Holds up across typical panel gamma. Still worth checking on an uncalibrated laptop, where mid-tones shift most.

In dark mode

Too dim on dark surfaces at 2.42:1 — lift it to #06818C for body text, or reserve it for fills.

Explore nearby colors

Small, deliberate steps away from this hex — useful when you are hunting for the version of a colour that finally feels right.

#04545b, answered

What color is #04545b?

#04545b is a deep electric cyan, closest to Dark Slate Gray (ΔE2000 6.1). It sits at 185° on the hue wheel with 92% saturation and 19% lightness, which reads as cool.

What is the RGB value of #04545b?

rgb(4, 84, 91) — 4 red, 84 green and 91 blue out of 255, or 1.6% / 32.9% / 35.7% by channel.

What is #04545b in HSL and HSV?

hsl(185, 92%, 19%) and hsv(185, 96%, 36%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #04545b a light or a dark color?

It is a dark color. Relative luminance is 0.0712 and perceived brightness is 28%, so white text on it reaches 8.66:1.

Should I use black or white text on #04545b?

White. It scores 8.66:1 against #04545b, versus 2.42:1 for black — AAA at any size.

Is #04545b accessible on a white background?

#04545b on white scores 8.66:1, which clears AAA at every size.

What is the complementary color of #04545b?

#5B0B04 sits directly opposite on the wheel. Softer options are the split-complements #5B0428 and #5B3604, which give the same contrast with far less vibration.

What colors go well with #04545b?

For interface work: #F4FAFA as the surface, #C0E9ED for borders, #4B949B for secondary text, #5D0212 as an accent and #05717A for hover and pressed states. For a palette, the analogous pair #045B36 and #04285B stays calm, while #5B0B04 is the loudest partner.

What is #04545b in CMYK for printing?

cmyk(96%, 8%, 0%, 64%). This is a screen-to-ink approximation — a color this saturated sits outside most CMYK gamuts and will print duller than it looks here.

Is #04545b warm or cool?

Cool — it scores 89 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #045B42; nudged cooler, #03395C.

Which Tailwind color is closest to #04545b?

The slate family — its 500 step is #64748b, ΔE2000 21.6 away. That is a visible difference, so define #04545b as a custom token rather than reaching for the built-in.

How do I use #04545b in Tailwind CSS?

Inline it as an arbitrary value with bg-[#04545b] or text-[#04545b], or register the whole ramp under theme.extend.colors.brand so you get bg-brand-500 and friends. The generated 50–950 scale on this page is ready to paste into your config.

What is #04545b with 50% opacity?

rgba(4, 84, 91, 0.5), or #04545b80 in eight-digit hex. Over white that composites to #82AAAD; over black, #022A2E.

Is #04545b a web-safe color?

No. The nearest web-safe colour is #006666, ΔE2000 7 away. The palette only matters for legacy displays and some email clients now.

What does the color #04545b mean?

As a cyan, it reads clean, technical, fresh. Cyan reads as water, air and infrastructure: cool, hygienic, engineered. At this chroma the effect is amplified — it will dominate whatever sits beside it.

What gradient works with #04545b?

The safest is same-hue elevation: linear-gradient(135deg, #078A96, #04545b 45%, #05717A). For more colour, a short hue run to #030D3E keeps it rich without turning muddy.

Work with #04545b in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #04545b at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.