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blue · cool

#373c5c

a dark, soft blue · cool · closest name: Dark Slate Blue

Token name suggestion: Dusk Harbour

RGB
55, 60, 92
HSL
232°, 25%, 29%
CMYK
40, 35, 0, 64
Luminance
0.0482

#373c5c is a dark soft blue, 232° on the wheel and 77/100 on the cool side. Put white text on it (10.70:1). As text it scores 10.70:1 on white — safe at any size. Nearest name is Dark Slate Blue, nearest Tailwind family is slate.

hsl(232 25% 29%)rgb(55 60 92)Base step 800AAA inkCool

At a glance

Every number on this page in one read: what #373c5c is made of, how bright it looks, and which way it leans.

Hex
#373c5c
Hue
232°
blue
Saturation
25%
soft
Lightness
29%
dark
Brightness
36%
HSV value
Perceived
25%
weighted brightness
Luminance
0.0482
WCAG relative
Temperature
Cool
77/100 cool
Color family
Blue
Tone
Soft
Best ink
White
10.70:1
Closest name
Dark Slate Blue
ΔE2000 10.4
Chroma
20.9
LCH, 0–130ish
OKLCH L
0.366
perceptual lightness
Tailwind
slate
500 · ΔE 20.2
Web-safe
#333366
nearest of 216
Where it sits
Hue232° of 360°
Saturation25%
Lightness29%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #373c5c.

Temperature
Warm ← → Cool77% 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
Red17%
Green67%
Blue16%

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

Every format

HEX#373c5c
HEX (8-digit)#373c5cff
RGBrgb(55, 60, 92)
RGBArgba(55, 60, 92, 1)
HSLhsl(232, 25%, 29%)
HSV / HSBhsv(232, 40%, 36%)
HWBhwb(232 22% 64%)
CMYKcmyk(40%, 35%, 0%, 64%)
LABlab(26.2 7.0 -19.8)
LCHlch(26.2 20.9 289.4)
OKLCHoklch(0.366 0.056 276.5)
XYZ (D65)xyz(5.12, 4.82, 10.78)
Decimal3619932
Display P3color(display-p3 0.216 0.235 0.361)
Web-safe#333366

Copy-ready code

every platformclick to select
/* CSS */
color: #373c5c;
background-color: #373c5c;
/* CSS custom property */
--brand: #373c5c;
/* Tailwind (arbitrary) */
class="text-[#373c5c] bg-[#373c5c]"
/* SCSS */
$brand: #373c5c;
/* SwiftUI */
Color(red: 0.216, green: 0.235, blue: 0.361)
/* UIKit */
UIColor(red: 0.216, green: 0.235, blue: 0.361, alpha: 1)
/* Android XML */
<color name="brand">#373C5C</color>
/* Android Compose */
Color(0xFF373C5C)
/* Flutter */
Color(0xFF373C5C)
/* Python / OpenCV (BGR) */
(92, 60, 55)
/* Python / PIL (RGB) */
(55, 60, 92)
/* Java AWT */
new Color(55, 60, 92)
/* .NET */
Color.FromArgb(255, 55, 60, 92)
/* OpenGL / Unity (0–1) */
(0.2157f, 0.2353f, 0.3608f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{55,60,92}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #373c5c 85%, white);
border-color: color-mix(in oklab, #373c5c 40%, transparent);
/* theme-aware in one line */
color: light-dark(#303450, #D9DBE8);
/* relative colour syntax */
--hover: hsl(from #373c5c 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: #F6F6F9;
  --brand-100: #EDEEF3;
  --brand-200: #D6D8E5;
  --brand-300: #B9BDD5;
  --brand-400: #969BC0;
  --brand-500: #737AAB;
  --brand-600: #5C6499;
  --brand-700: #4C5380;
  --brand-800: #373c5c;
  --brand-900: #2F334B;
  --brand-950: #1D202F;
  --brand: #373c5c;
  --brand-ink: #ffffff;
  --brand-surface: #F5F6F9;
  --brand-border: #CCCFE0;
  --brand-hover: #2A2D46;
  --brand-pressed: #1C1F2F;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #151723;
    --brand-ink: #D9DBE8;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F6F6F9',
        100: '#EDEEF3',
        200: '#D6D8E5',
        300: '#B9BDD5',
        400: '#969BC0',
        500: '#737AAB',
        600: '#5C6499',
        700: '#4C5380',
        800: '#373c5c',
        900: '#2F334B',
        950: '#1D202F',
        DEFAULT: '#373c5c',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F6F6F9,
  '100': #EDEEF3,
  '200': #D6D8E5,
  '300': #B9BDD5,
  '400': #969BC0,
  '500': #737AAB,
  '600': #5C6499,
  '700': #4C5380,
  '800': #373c5c,
  '900': #2F334B,
  '950': #1D202F,
);
$brand-base: #373c5c;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F6F6F9", "$type": "color" },
      "100": { "$value": "#EDEEF3", "$type": "color" },
      "200": { "$value": "#D6D8E5", "$type": "color" },
      "300": { "$value": "#B9BDD5", "$type": "color" },
      "400": { "$value": "#969BC0", "$type": "color" },
      "500": { "$value": "#737AAB", "$type": "color" },
      "600": { "$value": "#5C6499", "$type": "color" },
      "700": { "$value": "#4C5380", "$type": "color" },
      "800": { "$value": "#373c5c", "$type": "color" },
      "900": { "$value": "#2F334B", "$type": "color" },
      "950": { "$value": "#1D202F", "$type": "color" }
    },
    "brandInk": { "$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 #373c5c · 10.70:1
Use #ffffffAAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 10.70:1 · recommended
AA pass · AA large pass · AAA pass
Aa
Black text · 1.96:1
AA fail · AA large fail · AAA fail
Reading the other direction: #373c5c as text scores 10.70:1 on white and 1.96:1 on black.
Best tinted ink on it, if plain black or white feels flat: #EFF0F5 at 9.40:1.

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
#373c5c · 10.70:1
AA on whitealready passes
#373c5c
The quick fox
#373c5c · 10.70:1
AAA on whitealready passes
#373c5c
The quick fox
#6C74A7 · 4.69:1
AA on black+25% L
#6C74A7
The quick fox
#8F95BC · 7.19:1
AAA on black+36% L
#8F95BC

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #373C5C 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
#373c5c on white: 10.70:1
AA ✓ pass · AA-large · AAA
Aa
#373c5c on black: 1.96:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #373c5c as text on that neutral, and that neutral as text on #373c5c.

NeutralRatioBoth directions
White10.70:1AaAa
Slate 5010.22:1AaAa
Slate 1009.76:1AaAa
Slate 2008.68:1AaAa
Slate 3007.20:1AaAa
Slate 4004.17:1AaAa
Slate 5002.25:1AaAa
Slate 6001.41:1AaAa
Slate 7001.03:1AaAa
Slate 8001.37:1AaAa
Slate 9001.67:1AaAa
Black1.96:1AaAa
Colour vision deficiency
true color
protanopia · #32405D
deuteranopia · #2F3D5B
tritanopia · #2C4248

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. #373c5c is pinned to step 800; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F6F6F9
#EDEEF3
#D6D8E5
#B9BDD5
#969BC0
#737AAB
#5C6499
#4C5380
#373c5c
#2F334B
#1D202F
Base = 800Lightest = 50 · #F6F6F9Darkest = 950 · #1D202FText step on white = 600
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 0.014 276.5);
  --brand-100: oklch(0.94 0.022 276.5);
  --brand-200: oklch(0.88 0.033 276.5);
  --brand-300: oklch(0.80 0.043 276.5);
  --brand-400: oklch(0.72 0.051 276.5);
  --brand-500: oklch(0.64 0.056 276.5);
  --brand-600: oklch(0.56 0.056 276.5);
  --brand-700: oklch(0.48 0.052 276.5);
  --brand-800: oklch(0.40 0.047 276.5);
  --brand-900: oklch(0.32 0.039 276.5);
  --brand-950: oklch(0.24 0.031 276.5);
}

Colors that work with #373c5c

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#F5F6F9
Tinted page background
Border#CCCFE0
Hairlines and dividers
Muted text#565E90
Captions on the surface
Accent#5F4E34
Second voice, not a rival
Dark variant#303450
Hover, pressed, headers
Light variant#EFF0F5
Selected rows, tints
Dark surface#151723
Dark-mode background
Hover#2A2D46
One step down in lightness
Pressed#1C1F2F
Two steps down
Disabled#666D9D
Chroma pulled out
Focus ring#363E71
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 #373c5c

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

Works well for
  • Body text and links on white
  • Charts, tags and secondary surfaces
  • Headers, footers and dark-mode surfaces
  • Brand accents, badges and data highlights
Use with care
  • Text on black or near-black surfaces
  • Black text placed on it
  • 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.

trustedcalmcompetentcorporate

The default of institutions for a reason: blue is read as stable and safe across nearly every culture that has been surveyed.

The muted chroma softens the association — it reads considered rather than loud, which suits long-form and data-heavy screens. The low lightness adds weight and formality.

Worth knowing

It is also the most crowded hue on the web. Distinctiveness has to come from your other choices.

Reads as
  • FormalityHigh
  • EnergyMedium
  • Weight71/100
  • 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#5C5737
Analogous left#374E5C
Analogous right#44375C
Split-complement 1#5C4437
Split-complement 2#4E5C37
Triadic 1#5C373C
Triadic 2#3C5C37
Tetradic#5C374E
On the wheel
Base+30°−30°+120°+240°+180°232°

#373c5c sits at 232°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red21.6%
Green23.5%
Blue36.1%
R · 0–255
55
0x37
G · 0–255
60
0x3c
B · 0–255
92
0x5c

CMYK percentages

Cyan40.2%
Magenta34.8%
Yellow0.0%
Key (black)63.9%

Total ink coverage is 139%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#373c5c text on a black background

contrast 1.96:1

Card sample

#373c5c text on a white background

contrast 10.70:1

Card sample

#373c5c on grey

9.76:1

#373c5c on its own surface

9.90:1

#373c5c on its dark surface

1.67:1

CSS3 live lab

Text font color

The quick brown fox

color: #373c5c;
Background color
Panel with #373c5c background
background-color: #373c5c;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #373c5c;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(55, 60, 92, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(55, 60, 92, 0.45);
Border & gradient
Gradient panel
border: 3px solid #373c5c;
background: linear-gradient(135deg, #373c5c, #4B375C);
Gradient text

Gradient headline

background: linear-gradient(90deg, #373c5c, #54375C);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #373c5c;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #373c5c;
caret-color: #373c5c;
Left rule
Pull quote or callout
border-left: 4px solid #373c5c;
Ring + tint
Selected chip
background: #EFF0F5;
box-shadow: inset 0 0 0 2px #373c5c;
Conic badge
68%
background: conic-gradient(#373c5c 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #373c5c 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(55, 60, 92, 0.5)
rgb(55 60 92 / 50%)
#373c5c80
hsl(232 25% 29% / 50%)
color-mix(in srgb, #373c5c 50%, transparent)
Alpha8-digit hexFlat on white
10%#373c5c1a#EBECEF
20%#373c5c33#D7D8DE
40%#373c5c66#AFB1BE
60%#373c5c99#878A9D
80%#373c5ccc#5F637D

Gradients from #373c5c

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, #4E5582, #373c5c 45%, #303450);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #373c5c, #3E2B49);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #373c5c, #5C5737);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #596195 0%, #373c5c 45%, #303450 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F5F6F9, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #4A6E7C 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #56426F 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #303450 0%, transparent 65%), #373c5c;

Monochromatic scale

Palettes built from #373c5c

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.

#373c5c in the real world

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

Industries
TechnologyFinanceHealthcareEnterprise SaaS
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 1.96:1 — lift it to #6C74A7 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.

#373c5c, answered

What color is #373c5c?

#373c5c is a dark soft blue, closest to Dark Slate Blue (ΔE2000 10.4). It sits at 232° on the hue wheel with 25% saturation and 29% lightness, which reads as cool.

What is the RGB value of #373c5c?

rgb(55, 60, 92) — 55 red, 60 green and 92 blue out of 255, or 21.6% / 23.5% / 36.1% by channel.

What is #373c5c in HSL and HSV?

hsl(232, 25%, 29%) and hsv(232, 40%, 36%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #373c5c a light or a dark color?

It is a dark color. Relative luminance is 0.0482 and perceived brightness is 25%, so white text on it reaches 10.70:1.

Should I use black or white text on #373c5c?

White. It scores 10.70:1 against #373c5c, versus 1.96:1 for black — AAA at any size.

Is #373c5c accessible on a white background?

#373c5c on white scores 10.70:1, which clears AAA at every size.

What is the complementary color of #373c5c?

#5C5737 sits directly opposite on the wheel. Softer options are the split-complements #5C4437 and #4E5C37, which give the same contrast with far less vibration.

What colors go well with #373c5c?

For interface work: #F5F6F9 as the surface, #CCCFE0 for borders, #565E90 for secondary text, #5F4E34 as an accent and #303450 for hover and pressed states. For a palette, the analogous pair #374E5C and #44375C stays calm, while #5C5737 is the loudest partner.

What is #373c5c in CMYK for printing?

cmyk(40%, 35%, 0%, 64%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #373c5c warm or cool?

Cool — it scores 77 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #40375C; nudged cooler, #35465D.

Which Tailwind color is closest to #373c5c?

The slate family — its 500 step is #64748b, ΔE2000 20.2 away. That is a visible difference, so define #373c5c as a custom token rather than reaching for the built-in.

How do I use #373c5c in Tailwind CSS?

Inline it as an arbitrary value with bg-[#373c5c] or text-[#373c5c], 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 #373c5c with 50% opacity?

rgba(55, 60, 92, 0.5), or #373c5c80 in eight-digit hex. Over white that composites to #9B9EAE; over black, #1C1E2E.

Is #373c5c a web-safe color?

No. The nearest web-safe colour is #333366, ΔE2000 5.7 away. The palette only matters for legacy displays and some email clients now.

What does the color #373c5c mean?

As a blue, it reads trusted, calm, competent. The default of institutions for a reason: blue is read as stable and safe across nearly every culture that has been surveyed. At this moderate chroma the association is present but not shouted.

What gradient works with #373c5c?

The safest is same-hue elevation: linear-gradient(135deg, #4E5582, #373c5c 45%, #303450). For more colour, a short hue run to #3E2B49 keeps it rich without turning muddy.

Work with #373c5c in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #373c5c at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.