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cyan · cool

#123748

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

Token name suggestion: Midnight Teal

RGB
18, 55, 72
HSL
199°, 60%, 18%
CMYK
75, 24, 0, 72
Luminance
0.0333

#123748 is a deep vivid cyan, 199° on the wheel and 95/100 on the cool side. Put white text on it (12.61:1). As text it scores 12.61:1 on white — safe at any size. Nearest name is Dark Slate Gray, nearest Tailwind family is slate.

hsl(199 60% 18%)rgb(18 55 72)Base step 950AAA inkCool

At a glance

Every number on this page in one read: what #123748 is made of, how bright it looks, and which way it leans.

Hex
#123748
Hue
199°
cyan
Saturation
60%
vivid
Lightness
18%
deep
Brightness
28%
HSV value
Perceived
19%
weighted brightness
Luminance
0.0333
WCAG relative
Temperature
Cool
95/100 cool
Color family
Cyan
Tone
Vivid
Best ink
White
12.61:1
Closest name
Dark Slate Gray
ΔE2000 12.1
Chroma
15.8
LCH, 0–130ish
OKLCH L
0.319
perceptual lightness
Tailwind
slate
500 · ΔE 23.2
Web-safe
#003333
nearest of 216
Where it sits
Hue199° of 360°
Saturation60%
Lightness18%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #123748.

Temperature
Warm ← → Cool95% 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
Red4%
Green82%
Blue14%

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

Every format

HEX#123748
HEX (8-digit)#123748ff
RGBrgb(18, 55, 72)
RGBArgba(18, 55, 72, 1)
HSLhsl(199, 60%, 18%)
HSV / HSBhsv(199, 75%, 28%)
HWBhwb(199 7% 72%)
CMYKcmyk(75%, 24%, 0%, 72%)
LABlab(21.3 -6.7 -14.3)
LCHlch(21.3 15.8 245.0)
OKLCHoklch(0.319 0.051 231.5)
XYZ (D65)xyz(2.78, 3.33, 6.63)
Decimal1193800
Display P3color(display-p3 0.071 0.216 0.282)
Web-safe#003333

Copy-ready code

every platformclick to select
/* CSS */
color: #123748;
background-color: #123748;
/* CSS custom property */
--brand: #123748;
/* Tailwind (arbitrary) */
class="text-[#123748] bg-[#123748]"
/* SCSS */
$brand: #123748;
/* SwiftUI */
Color(red: 0.071, green: 0.216, blue: 0.282)
/* UIKit */
UIColor(red: 0.071, green: 0.216, blue: 0.282, alpha: 1)
/* Android XML */
<color name="brand">#123748</color>
/* Android Compose */
Color(0xFF123748)
/* Flutter */
Color(0xFF123748)
/* Python / OpenCV (BGR) */
(72, 55, 18)
/* Python / PIL (RGB) */
(18, 55, 72)
/* Java AWT */
new Color(18, 55, 72)
/* .NET */
Color.FromArgb(255, 18, 55, 72)
/* OpenGL / Unity (0–1) */
(0.0706f, 0.2157f, 0.2824f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{18,55,72}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #123748 85%, white);
border-color: color-mix(in oklab, #123748 40%, transparent);
/* theme-aware in one line */
color: light-dark(#1A4E66, #D3E5EE);
/* relative colour syntax */
--hover: hsl(from #123748 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: #F4F9FB;
  --brand-100: #E9F2F7;
  --brand-200: #CCE4EF;
  --brand-300: #A5D3E9;
  --brand-400: #78BEDD;
  --brand-500: #4BA8D2;
  --brand-600: #3196C4;
  --brand-700: #297DA3;
  --brand-800: #216483;
  --brand-900: #1B4A5F;
  --brand-950: #123748;
  --brand: #123748;
  --brand-ink: #ffffff;
  --brand-surface: #F4F8FA;
  --brand-border: #C0DFED;
  --brand-hover: #0B212B;
  --brand-pressed: #040B0F;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141F24;
    --brand-ink: #D3E5EE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F4F9FB',
        100: '#E9F2F7',
        200: '#CCE4EF',
        300: '#A5D3E9',
        400: '#78BEDD',
        500: '#4BA8D2',
        600: '#3196C4',
        700: '#297DA3',
        800: '#216483',
        900: '#1B4A5F',
        950: '#123748',
        DEFAULT: '#123748',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F4F9FB,
  '100': #E9F2F7,
  '200': #CCE4EF,
  '300': #A5D3E9,
  '400': #78BEDD,
  '500': #4BA8D2,
  '600': #3196C4,
  '700': #297DA3,
  '800': #216483,
  '900': #1B4A5F,
  '950': #123748,
);
$brand-base: #123748;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F4F9FB", "$type": "color" },
      "100": { "$value": "#E9F2F7", "$type": "color" },
      "200": { "$value": "#CCE4EF", "$type": "color" },
      "300": { "$value": "#A5D3E9", "$type": "color" },
      "400": { "$value": "#78BEDD", "$type": "color" },
      "500": { "$value": "#4BA8D2", "$type": "color" },
      "600": { "$value": "#3196C4", "$type": "color" },
      "700": { "$value": "#297DA3", "$type": "color" },
      "800": { "$value": "#216483", "$type": "color" },
      "900": { "$value": "#1B4A5F", "$type": "color" },
      "950": { "$value": "#123748", "$type": "color" }
    },
    "brandInk": { "$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 #123748 · 12.61:1
Use #ffffffAAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 12.61:1 · recommended
AA pass · AA large pass · AAA pass
Aa
Black text · 1.67:1
AA fail · AA large fail · AAA fail
Reading the other direction: #123748 as text scores 12.61:1 on white and 1.67:1 on black.
Best tinted ink on it, if plain black or white feels flat: #EBF5FA at 11.39:1.

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
#123748 · 12.61:1
AA on whitealready passes
#123748
The quick fox
#123748 · 12.61:1
AAA on whitealready passes
#123748
The quick fox
#297FA6 · 4.68:1
AA on black+23% L
#297FA6
The quick fox
#3A9FCE · 7.03:1
AAA on black+34% L
#3A9FCE

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #123748 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
#123748 on white: 12.61:1
AA ✓ pass · AA-large · AAA
Aa
#123748 on black: 1.67:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #123748 as text on that neutral, and that neutral as text on #123748.

NeutralRatioBoth directions
White12.61:1AaAa
Slate 5012.05:1AaAa
Slate 10011.51:1AaAa
Slate 20010.23:1AaAa
Slate 3008.49:1AaAa
Slate 4004.92:1AaAa
Slate 5002.65:1AaAa
Slate 6001.66:1AaAa
Slate 7001.22:1AaAa
Slate 8001.16:1AaAa
Slate 9001.42:1AaAa
Black1.67:1AaAa
Colour vision deficiency
true color
protanopia · #2E3649
deuteranopia · #273148
tritanopia · #003C3D

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. #123748 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.

#F4F9FB
#E9F2F7
#CCE4EF
#A5D3E9
#78BEDD
#4BA8D2
#3196C4
#297DA3
#216483
#1B4A5F
#123748
Base = 950Lightest = 50 · #F4F9FBDarkest = 950 · #123748Text step on white = 700
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 0.013 231.5);
  --brand-100: oklch(0.94 0.021 231.5);
  --brand-200: oklch(0.88 0.031 231.5);
  --brand-300: oklch(0.80 0.040 231.5);
  --brand-400: oklch(0.72 0.047 231.5);
  --brand-500: oklch(0.64 0.051 231.5);
  --brand-600: oklch(0.56 0.051 231.5);
  --brand-700: oklch(0.48 0.048 231.5);
  --brand-800: oklch(0.40 0.043 231.5);
  --brand-900: oklch(0.32 0.036 231.5);
  --brand-950: oklch(0.24 0.028 231.5);
}

Colors that work with #123748

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#F4F8FA
Tinted page background
Border#C0DFED
Hairlines and dividers
Muted text#4B829B
Captions on the surface
Accent#4A1410
Second voice, not a rival
Dark variant#1A4E66
Hover, pressed, headers
Light variant#EBF5FA
Selected rows, tints
Dark surface#141F24
Dark-mode background
Hover#0B212B
One step down in lightness
Pressed#040B0F
Two steps down
Disabled#4F6D7B
Chroma pulled out
Focus ring#11455E
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 #123748

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.

This is a confident chroma: strong enough to lead a brand, restrained enough to live in an interface all day. 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
  • EnergyMedium-high
  • Weight82/100
  • 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#482312
Analogous left#12483E
Analogous right#121C48
Split-complement 1#48121C
Split-complement 2#483E12
Triadic 1#481237
Triadic 2#374812
Tetradic#3E1248
On the wheel
Base+30°−30°+120°+240°+180°199°

#123748 sits at 199°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red7.1%
Green21.6%
Blue28.2%
R · 0–255
18
0x12
G · 0–255
55
0x37
B · 0–255
72
0x48

CMYK percentages

Cyan75.0%
Magenta23.6%
Yellow0.0%
Key (black)71.8%

Total ink coverage is 170%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#123748 text on a black background

contrast 1.67:1

Card sample

#123748 text on a white background

contrast 12.61:1

Card sample

#123748 on grey

11.51:1

#123748 on its own surface

11.80:1

#123748 on its dark surface

1.33:1

CSS3 live lab

Text font color

The quick brown fox

color: #123748;
Background color
Panel with #123748 background
background-color: #123748;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #123748;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(18, 55, 72, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(18, 55, 72, 0.45);
Border & gradient
Gradient panel
border: 3px solid #123748;
background: linear-gradient(135deg, #123748, #121348);
Gradient text

Gradient headline

background: linear-gradient(90deg, #123748, #1E1248);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #123748;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #123748;
caret-color: #123748;
Left rule
Pull quote or callout
border-left: 4px solid #123748;
Ring + tint
Selected chip
background: #EBF5FA;
box-shadow: inset 0 0 0 2px #123748;
Conic badge
68%
background: conic-gradient(#123748 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #123748 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(18, 55, 72, 0.5)
rgb(18 55 72 / 50%)
#12374880
hsl(199 60% 18% / 50%)
color-mix(in srgb, #123748 50%, transparent)
Alpha8-digit hexFlat on white
10%#1237481a#E7EBED
20%#12374833#D0D7DA
40%#12374866#A0AFB6
60%#12374899#718791
80%#123748cc#415F6D

Gradients from #123748

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, #1E5C79, #123748 45%, #1A4E66);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #123748, #0E0C2F);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #123748, #482312);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #246F91 0%, #123748 45%, #1A4E66 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F4F8FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #1C715A 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #181F60 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #1A4E66 0%, transparent 65%), #123748;

Monochromatic scale

Palettes built from #123748

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.

#123748 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

Converts to four-color process without much drama. Proof it anyway.

On screens

Very dark values collapse into each other on cheap panels — leave more lightness between your darkest steps than the numbers suggest.

In dark mode

Too dim on dark surfaces at 1.67:1 — lift it to #297FA6 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.

#123748, answered

What color is #123748?

#123748 is a deep vivid cyan, closest to Dark Slate Gray (ΔE2000 12.1). It sits at 199° on the hue wheel with 60% saturation and 18% lightness, which reads as cool.

What is the RGB value of #123748?

rgb(18, 55, 72) — 18 red, 55 green and 72 blue out of 255, or 7.1% / 21.6% / 28.2% by channel.

What is #123748 in HSL and HSV?

hsl(199, 60%, 18%) and hsv(199, 75%, 28%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #123748 a light or a dark color?

It is a dark color. Relative luminance is 0.0333 and perceived brightness is 19%, so white text on it reaches 12.61:1.

Should I use black or white text on #123748?

White. It scores 12.61:1 against #123748, versus 1.67:1 for black — AAA at any size.

Is #123748 accessible on a white background?

#123748 on white scores 12.61:1, which clears AAA at every size.

What is the complementary color of #123748?

#482312 sits directly opposite on the wheel. Softer options are the split-complements #48121C and #483E12, which give the same contrast with far less vibration.

What colors go well with #123748?

For interface work: #F4F8FA as the surface, #C0DFED for borders, #4B829B for secondary text, #4A1410 as an accent and #1A4E66 for hover and pressed states. For a palette, the analogous pair #12483E and #121C48 stays calm, while #482312 is the loudest partner.

What is #123748 in CMYK for printing?

cmyk(75%, 24%, 0%, 72%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #123748 warm or cool?

Cool — it scores 95 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #124845; nudged cooler, #112E49.

Which Tailwind color is closest to #123748?

The slate family — its 500 step is #64748b, ΔE2000 23.2 away. That is a visible difference, so define #123748 as a custom token rather than reaching for the built-in.

How do I use #123748 in Tailwind CSS?

Inline it as an arbitrary value with bg-[#123748] or text-[#123748], 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 #123748 with 50% opacity?

rgba(18, 55, 72, 0.5), or #12374880 in eight-digit hex. Over white that composites to #899BA4; over black, #091C24.

Is #123748 a web-safe color?

No. The nearest web-safe colour is #003333, ΔE2000 11.2 away. The palette only matters for legacy displays and some email clients now.

What does the color #123748 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 #123748?

The safest is same-hue elevation: linear-gradient(135deg, #1E5C79, #123748 45%, #1A4E66). For more colour, a short hue run to #0E0C2F keeps it rich without turning muddy.

Work with #123748 in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #123748 at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.