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blue · cool

#243353

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

Token name suggestion: Ink Sapphire

RGB
36, 51, 83
HSL
221°, 40%, 23%
CMYK
57, 39, 0, 68
Luminance
0.0337

#243353 is a deep soft blue, 221° on the wheel and 94/100 on the cool side. Put white text on it (12.55:1). As text it scores 12.55:1 on white — safe at any size. Nearest name is Dark Slate Blue, nearest Tailwind family is slate.

hsl(221 40% 23%)rgb(36 51 83)Base step 900AAA inkCool

At a glance

Every number on this page in one read: what #243353 is made of, how bright it looks, and which way it leans.

Hex
#243353
Hue
221°
blue
Saturation
40%
soft
Lightness
23%
deep
Brightness
33%
HSV value
Perceived
20%
weighted brightness
Luminance
0.0337
WCAG relative
Temperature
Cool
94/100 cool
Color family
Blue
Tone
Soft
Best ink
White
12.55:1
Closest name
Dark Slate Blue
ΔE2000 11.6
Chroma
21.9
LCH, 0–130ish
OKLCH L
0.324
perceptual lightness
Tailwind
slate
500 · ΔE 22.7
Web-safe
#333366
nearest of 216
Where it sits
Hue221° of 360°
Saturation40%
Lightness23%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #243353.

Temperature
Warm ← → Cool94% 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
Red11%
Green70%
Blue19%

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

Every format

HEX#243353
HEX (8-digit)#243353ff
RGBrgb(36, 51, 83)
RGBArgba(36, 51, 83, 1)
HSLhsl(221, 40%, 23%)
HSV / HSBhsv(221, 57%, 33%)
HWBhwb(221 14% 67%)
CMYKcmyk(57%, 39%, 0%, 68%)
LABlab(21.5 4.5 -21.4)
LCHlch(21.5 21.9 281.8)
OKLCHoklch(0.324 0.061 264.2)
XYZ (D65)xyz(3.47, 3.37, 8.65)
Decimal2372435
Display P3color(display-p3 0.141 0.200 0.325)
Web-safe#333366

Copy-ready code

every platformclick to select
/* CSS */
color: #243353;
background-color: #243353;
/* CSS custom property */
--brand: #243353;
/* Tailwind (arbitrary) */
class="text-[#243353] bg-[#243353]"
/* SCSS */
$brand: #243353;
/* SwiftUI */
Color(red: 0.141, green: 0.200, blue: 0.325)
/* UIKit */
UIColor(red: 0.141, green: 0.200, blue: 0.325, alpha: 1)
/* Android XML */
<color name="brand">#243353</color>
/* Android Compose */
Color(0xFF243353)
/* Flutter */
Color(0xFF243353)
/* Python / OpenCV (BGR) */
(83, 51, 36)
/* Python / PIL (RGB) */
(36, 51, 83)
/* Java AWT */
new Color(36, 51, 83)
/* .NET */
Color.FromArgb(255, 36, 51, 83)
/* OpenGL / Unity (0–1) */
(0.1412f, 0.2000f, 0.3255f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{36,51,83}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #243353 85%, white);
border-color: color-mix(in oklab, #243353 40%, transparent);
/* theme-aware in one line */
color: light-dark(#273759, #D4DCEC);
/* relative colour syntax */
--hover: hsl(from #243353 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: #F5F6FA;
  --brand-100: #EBEEF4;
  --brand-200: #D2DAE9;
  --brand-300: #B1BFDD;
  --brand-400: #8A9FCC;
  --brand-500: #627FBB;
  --brand-600: #4A69AB;
  --brand-700: #3E578E;
  --brand-800: #314672;
  --brand-900: #243353;
  --brand-950: #182134;
  --brand: #243353;
  --brand-ink: #ffffff;
  --brand-surface: #F4F6FA;
  --brand-border: #C6D0E6;
  --brand-hover: #19243A;
  --brand-pressed: #0E1421;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141924;
    --brand-ink: #D4DCEC;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F5F6FA',
        100: '#EBEEF4',
        200: '#D2DAE9',
        300: '#B1BFDD',
        400: '#8A9FCC',
        500: '#627FBB',
        600: '#4A69AB',
        700: '#3E578E',
        800: '#314672',
        900: '#243353',
        950: '#182134',
        DEFAULT: '#243353',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F5F6FA,
  '100': #EBEEF4,
  '200': #D2DAE9,
  '300': #B1BFDD,
  '400': #8A9FCC,
  '500': #627FBB,
  '600': #4A69AB,
  '700': #3E578E,
  '800': #314672,
  '900': #243353,
  '950': #182134,
);
$brand-base: #243353;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F5F6FA", "$type": "color" },
      "100": { "$value": "#EBEEF4", "$type": "color" },
      "200": { "$value": "#D2DAE9", "$type": "color" },
      "300": { "$value": "#B1BFDD", "$type": "color" },
      "400": { "$value": "#8A9FCC", "$type": "color" },
      "500": { "$value": "#627FBB", "$type": "color" },
      "600": { "$value": "#4A69AB", "$type": "color" },
      "700": { "$value": "#3E578E", "$type": "color" },
      "800": { "$value": "#314672", "$type": "color" },
      "900": { "$value": "#243353", "$type": "color" },
      "950": { "$value": "#182134", "$type": "color" }
    },
    "brandInk": { "$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 #243353 · 12.55:1
Use #ffffffAAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 12.55:1 · 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: #243353 as text scores 12.55:1 on white and 1.67:1 on black.
Best tinted ink on it, if plain black or white feels flat: #EDF0F7 at 11.00:1.

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
#243353 · 12.55:1
AA on whitealready passes
#243353
The quick fox
#243353 · 12.55:1
AAA on whitealready passes
#243353
The quick fox
#5574B5 · 4.55:1
AA on black+29% L
#5574B5
The quick fox
#8097C8 · 7.18:1
AAA on black+41% L
#8097C8

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #243353 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
#243353 on white: 12.55:1
AA ✓ pass · AA-large · AAA
Aa
#243353 on black: 1.67:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #243353 as text on that neutral, and that neutral as text on #243353.

NeutralRatioBoth directions
White12.55:1AaAa
Slate 5011.99:1AaAa
Slate 10011.45:1AaAa
Slate 20010.18:1AaAa
Slate 3008.45:1AaAa
Slate 4004.89:1AaAa
Slate 5002.64:1AaAa
Slate 6001.66:1AaAa
Slate 7001.21:1AaAa
Slate 8001.17:1AaAa
Slate 9001.42:1AaAa
Black1.67:1AaAa
Colour vision deficiency
true color
protanopia · #263654
deuteranopia · #213252
tritanopia · #0D3A3F

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. #243353 is pinned to step 900; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F5F6FA
#EBEEF4
#D2DAE9
#B1BFDD
#8A9FCC
#627FBB
#4A69AB
#3E578E
#314672
#243353
#182134
Base = 900Lightest = 50 · #F5F6FADarkest = 950 · #182134Text 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 0.015 264.2);
  --brand-100: oklch(0.94 0.024 264.2);
  --brand-200: oklch(0.88 0.036 264.2);
  --brand-300: oklch(0.80 0.047 264.2);
  --brand-400: oklch(0.72 0.056 264.2);
  --brand-500: oklch(0.64 0.061 264.2);
  --brand-600: oklch(0.56 0.061 264.2);
  --brand-700: oklch(0.48 0.057 264.2);
  --brand-800: oklch(0.40 0.051 264.2);
  --brand-900: oklch(0.32 0.042 264.2);
  --brand-950: oklch(0.24 0.033 264.2);
}

Colors that work with #243353

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#F4F6FA
Tinted page background
Border#C6D0E6
Hairlines and dividers
Muted text#4B649B
Captions on the surface
Accent#553822
Second voice, not a rival
Dark variant#273759
Hover, pressed, headers
Light variant#EDF0F7
Selected rows, tints
Dark surface#141924
Dark-mode background
Hover#19243A
One step down in lightness
Pressed#0E1421
Two steps down
Disabled#5A6A8D
Chroma pulled out
Focus ring#233968
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 #243353

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
  • Weight77/100
  • 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#534424
Analogous left#244A53
Analogous right#2C2453
Split-complement 1#532C24
Split-complement 2#4A5324
Triadic 1#532433
Triadic 2#335324
Tetradic#53244A
On the wheel
Base+30°−30°+120°+240°+180°221°

#243353 sits at 221°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red14.1%
Green20.0%
Blue32.5%
R · 0–255
36
0x24
G · 0–255
51
0x33
B · 0–255
83
0x53

CMYK percentages

Cyan56.6%
Magenta38.6%
Yellow0.0%
Key (black)67.5%

Total ink coverage is 163%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#243353 text on a black background

contrast 1.67:1

Card sample

#243353 text on a white background

contrast 12.55:1

Card sample

#243353 on grey

11.45:1

#243353 on its own surface

11.60:1

#243353 on its dark surface

1.40:1

CSS3 live lab

Text font color

The quick brown fox

color: #243353;
Background color
Panel with #243353 background
background-color: #243353;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #243353;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(36, 51, 83, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(36, 51, 83, 0.45);
Border & gradient
Gradient panel
border: 3px solid #243353;
background: linear-gradient(135deg, #243353, #342453);
Gradient text

Gradient headline

background: linear-gradient(90deg, #243353, #402453);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #243353;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #243353;
caret-color: #243353;
Left rule
Pull quote or callout
border-left: 4px solid #243353;
Ring + tint
Selected chip
background: #EDF0F7;
box-shadow: inset 0 0 0 2px #243353;
Conic badge
68%
background: conic-gradient(#243353 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #243353 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(36, 51, 83, 0.5)
rgb(36 51 83 / 50%)
#24335380
hsl(221 40% 23% / 50%)
color-mix(in srgb, #243353 50%, transparent)
Alpha8-digit hexFlat on white
10%#2433531a#E9EBEE
20%#24335333#D3D6DD
40%#24335366#A7ADBA
60%#24335399#7C8598
80%#243353cc#505C75

Gradients from #243353

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, #364D7E, #243353 45%, #273759);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #243353, #2A1B3E);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #243353, #534424);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #405A93 0%, #243353 45%, #273759 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F4F6FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #337076 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #3D2D68 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #273759 0%, transparent 65%), #243353;

Monochromatic scale

Palettes built from #243353

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.

#243353 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 1.67:1 — lift it to #5574B5 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.

#243353, answered

What color is #243353?

#243353 is a deep soft blue, closest to Dark Slate Blue (ΔE2000 11.6). It sits at 221° on the hue wheel with 40% saturation and 23% lightness, which reads as cool.

What is the RGB value of #243353?

rgb(36, 51, 83) — 36 red, 51 green and 83 blue out of 255, or 14.1% / 20% / 32.5% by channel.

What is #243353 in HSL and HSV?

hsl(221, 40%, 23%) and hsv(221, 57%, 33%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #243353 a light or a dark color?

It is a dark color. Relative luminance is 0.0337 and perceived brightness is 20%, so white text on it reaches 12.55:1.

Should I use black or white text on #243353?

White. It scores 12.55:1 against #243353, versus 1.67:1 for black — AAA at any size.

Is #243353 accessible on a white background?

#243353 on white scores 12.55:1, which clears AAA at every size.

What is the complementary color of #243353?

#534424 sits directly opposite on the wheel. Softer options are the split-complements #532C24 and #4A5324, which give the same contrast with far less vibration.

What colors go well with #243353?

For interface work: #F4F6FA as the surface, #C6D0E6 for borders, #4B649B for secondary text, #553822 as an accent and #273759 for hover and pressed states. For a palette, the analogous pair #244A53 and #2C2453 stays calm, while #534424 is the loudest partner.

What is #243353 in CMYK for printing?

cmyk(57%, 39%, 0%, 68%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #243353 warm or cool?

Cool — it scores 94 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #262453; nudged cooler, #233954.

Which Tailwind color is closest to #243353?

The slate family — its 500 step is #64748b, ΔE2000 22.7 away. That is a visible difference, so define #243353 as a custom token rather than reaching for the built-in.

How do I use #243353 in Tailwind CSS?

Inline it as an arbitrary value with bg-[#243353] or text-[#243353], 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 #243353 with 50% opacity?

rgba(36, 51, 83, 0.5), or #24335380 in eight-digit hex. Over white that composites to #9299A9; over black, #121A2A.

Is #243353 a web-safe color?

No. The nearest web-safe colour is #333366, ΔE2000 6.2 away. The palette only matters for legacy displays and some email clients now.

What does the color #243353 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 #243353?

The safest is same-hue elevation: linear-gradient(135deg, #364D7E, #243353 45%, #273759). For more colour, a short hue run to #2A1B3E keeps it rich without turning muddy.

Work with #243353 in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #243353 at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.