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blue · cool

#2139ac

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

Token name suggestion: Dusk Cobalt

RGB
33, 57, 172
HSL
230°, 68%, 40%
CMYK
81, 67, 0, 33
Luminance
0.0623

#2139ac is a dark vivid blue, 230° on the wheel and 89/100 on the cool side. Put white text on it (9.35:1). As text it scores 9.35:1 on white — safe at any size. Nearest name is Dark Slate Blue, nearest Tailwind family is indigo.

hsl(230 68% 40%)rgb(33 57 172)Base step 700AAA inkCool

At a glance

Every number on this page in one read: what #2139ac is made of, how bright it looks, and which way it leans.

Hex
#2139ac
Hue
230°
blue
Saturation
68%
vivid
Lightness
40%
dark
Brightness
67%
HSV value
Perceived
29%
weighted brightness
Luminance
0.0623
WCAG relative
Temperature
Cool
89/100 cool
Color family
Blue
Tone
Vivid
Best ink
White
9.35:1
Closest name
Dark Slate Blue
ΔE2000 7.5
Chroma
72.2
LCH, 0–130ish
OKLCH L
0.410
perceptual lightness
Tailwind
indigo
500 · ΔE 17.8
Web-safe
#333399
nearest of 216
Where it sits
Hue230° of 360°
Saturation68%
Lightness40%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #2139ac.

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
Red5%
Green47%
Blue48%

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

Every format

HEX#2139ac
HEX (8-digit)#2139acff
RGBrgb(33, 57, 172)
RGBArgba(33, 57, 172, 1)
HSLhsl(230, 68%, 40%)
HSV / HSBhsv(230, 81%, 67%)
HWBhwb(230 13% 33%)
CMYKcmyk(81%, 67%, 0%, 33%)
LABlab(30.0 34.1 -63.6)
LCHlch(30.0 72.2 298.2)
OKLCHoklch(0.410 0.184 267.6)
XYZ (D65)xyz(9.53, 6.23, 39.72)
Decimal2177452
Display P3color(display-p3 0.129 0.224 0.675)
Web-safe#333399

Copy-ready code

every platformclick to select
/* CSS */
color: #2139ac;
background-color: #2139ac;
/* CSS custom property */
--brand: #2139ac;
/* Tailwind (arbitrary) */
class="text-[#2139ac] bg-[#2139ac]"
/* SCSS */
$brand: #2139ac;
/* SwiftUI */
Color(red: 0.129, green: 0.224, blue: 0.675)
/* UIKit */
UIColor(red: 0.129, green: 0.224, blue: 0.675, alpha: 1)
/* Android XML */
<color name="brand">#2139AC</color>
/* Android Compose */
Color(0xFF2139AC)
/* Flutter */
Color(0xFF2139AC)
/* Python / OpenCV (BGR) */
(172, 57, 33)
/* Python / PIL (RGB) */
(33, 57, 172)
/* Java AWT */
new Color(33, 57, 172)
/* .NET */
Color.FromArgb(255, 33, 57, 172)
/* OpenGL / Unity (0–1) */
(0.1294f, 0.2235f, 0.6745f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{33,57,172}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #2139ac 85%, white);
border-color: color-mix(in oklab, #2139ac 40%, transparent);
/* theme-aware in one line */
color: light-dark(#15246B, #D3D7EE);
/* relative colour syntax */
--hover: hsl(from #2139ac 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: #F3F5FB;
  --brand-100: #E8EAF8;
  --brand-200: #CAD1F2;
  --brand-300: #A1AEED;
  --brand-400: #7286E4;
  --brand-500: #435DDB;
  --brand-600: #2744CD;
  --brand-700: #2139ac;
  --brand-800: #1A2D89;
  --brand-900: #172463;
  --brand-950: #0E173E;
  --brand: #2139ac;
  --brand-ink: #ffffff;
  --brand-surface: #F4F5FA;
  --brand-border: #C0C8ED;
  --brand-hover: #1B2F8E;
  --brand-pressed: #162570;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141724;
    --brand-ink: #D3D7EE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F3F5FB',
        100: '#E8EAF8',
        200: '#CAD1F2',
        300: '#A1AEED',
        400: '#7286E4',
        500: '#435DDB',
        600: '#2744CD',
        700: '#2139ac',
        800: '#1A2D89',
        900: '#172463',
        950: '#0E173E',
        DEFAULT: '#2139ac',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F3F5FB,
  '100': #E8EAF8,
  '200': #CAD1F2,
  '300': #A1AEED,
  '400': #7286E4,
  '500': #435DDB,
  '600': #2744CD,
  '700': #2139ac,
  '800': #1A2D89,
  '900': #172463,
  '950': #0E173E,
);
$brand-base: #2139ac;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F3F5FB", "$type": "color" },
      "100": { "$value": "#E8EAF8", "$type": "color" },
      "200": { "$value": "#CAD1F2", "$type": "color" },
      "300": { "$value": "#A1AEED", "$type": "color" },
      "400": { "$value": "#7286E4", "$type": "color" },
      "500": { "$value": "#435DDB", "$type": "color" },
      "600": { "$value": "#2744CD", "$type": "color" },
      "700": { "$value": "#2139ac", "$type": "color" },
      "800": { "$value": "#1A2D89", "$type": "color" },
      "900": { "$value": "#172463", "$type": "color" },
      "950": { "$value": "#0E173E", "$type": "color" }
    },
    "brandInk": { "$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 #2139ac · 9.35:1
Use #ffffffAAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 9.35:1 · recommended
AA pass · AA large pass · AAA pass
Aa
Black text · 2.25:1
AA fail · AA large fail · AAA fail
Reading the other direction: #2139ac as text scores 9.35:1 on white and 2.25:1 on black.
Best tinted ink on it, if plain black or white feels flat: #EAEDFB at 8.02:1.

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
#2139ac · 9.35:1
AA on whitealready passes
#2139ac
The quick fox
#2139ac · 9.35:1
AAA on whitealready passes
#2139ac
The quick fox
#556DDE · 4.63:1
AA on black+20% L
#556DDE
The quick fox
#7F91E7 · 7.11:1
AAA on black+30% L
#7F91E7

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #2139AC 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
#2139ac on white: 9.35:1
AA ✓ pass · AA-large · AAA
Aa
#2139ac on black: 2.25:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #2139ac as text on that neutral, and that neutral as text on #2139ac.

NeutralRatioBoth directions
White9.35:1AaAa
Slate 508.94:1AaAa
Slate 1008.54:1AaAa
Slate 2007.59:1AaAa
Slate 3006.30:1AaAa
Slate 4003.65:1AaAa
Slate 5001.97:1AaAa
Slate 6001.23:1AaAa
Slate 7001.11:1AaAa
Slate 8001.56:1AaAa
Slate 9001.91:1AaAa
Black2.25:1AaAa
Colour vision deficiency
true color
protanopia · #004DB0
deuteranopia · #0040AA
tritanopia · #00586D

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. #2139ac is pinned to step 700; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F3F5FB
#E8EAF8
#CAD1F2
#A1AEED
#7286E4
#435DDB
#2744CD
#2139ac
#1A2D89
#172463
#0E173E
Base = 700Lightest = 50 · #F3F5FBDarkest = 950 · #0E173EText step on white = 500
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 0.046 267.6);
  --brand-100: oklch(0.94 0.074 267.6);
  --brand-200: oklch(0.88 0.111 267.6);
  --brand-300: oklch(0.80 0.144 267.6);
  --brand-400: oklch(0.72 0.170 267.6);
  --brand-500: oklch(0.64 0.184 267.6);
  --brand-600: oklch(0.56 0.184 267.6);
  --brand-700: oklch(0.48 0.173 267.6);
  --brand-800: oklch(0.40 0.155 267.6);
  --brand-900: oklch(0.32 0.129 267.6);
  --brand-950: oklch(0.24 0.101 267.6);
}

Colors that work with #2139ac

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#F4F5FA
Tinted page background
Border#C0C8ED
Hairlines and dividers
Muted text#4B599B
Captions on the surface
Accent#B0721D
Second voice, not a rival
Dark variant#15246B
Hover, pressed, headers
Light variant#EAEDFB
Selected rows, tints
Dark surface#141724
Dark-mode background
Hover#1B2F8E
One step down in lightness
Pressed#162570
Two steps down
Disabled#8991B4
Chroma pulled out
Focus ring#1937C8
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 #2139ac

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
  • 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.

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

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

Reads as
  • FormalityHigh
  • EnergyMedium-high
  • Weight60/100
  • 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#AC9421
Analogous left#217FAC
Analogous right#4E21AC
Split-complement 1#AC4E21
Split-complement 2#7FAC21
Triadic 1#AC2139
Triadic 2#39AC21
Tetradic#AC217F
On the wheel
Base+30°−30°+120°+240°+180°230°

#2139ac sits at 230°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red12.9%
Green22.4%
Blue67.5%
R · 0–255
33
0x21
G · 0–255
57
0x39
B · 0–255
172
0xac

CMYK percentages

Cyan80.8%
Magenta66.9%
Yellow0.0%
Key (black)32.5%

Total ink coverage is 180%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#2139ac text on a black background

contrast 2.25:1

Card sample

#2139ac text on a white background

contrast 9.35:1

Card sample

#2139ac on grey

8.54:1

#2139ac on its own surface

8.59:1

#2139ac on its dark surface

1.91:1

CSS3 live lab

Text font color

The quick brown fox

color: #2139ac;
Background color
Panel with #2139ac background
background-color: #2139ac;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #2139ac;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(33, 57, 172, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(33, 57, 172, 0.45);
Border & gradient
Gradient panel
border: 3px solid #2139ac;
background: linear-gradient(135deg, #2139ac, #6621AC);
Gradient text

Gradient headline

background: linear-gradient(90deg, #2139ac, #8821AC);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #2139ac;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #2139ac;
caret-color: #2139ac;
Left rule
Pull quote or callout
border-left: 4px solid #2139ac;
Ring + tint
Selected chip
background: #EAEDFB;
box-shadow: inset 0 0 0 2px #2139ac;
Conic badge
68%
background: conic-gradient(#2139ac 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #2139ac 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(33, 57, 172, 0.5)
rgb(33 57 172 / 50%)
#2139ac80
hsl(230 68% 40% / 50%)
color-mix(in srgb, #2139ac 50%, transparent)
Alpha8-digit hexFlat on white
10%#2139ac1a#E9EBF7
20%#2139ac33#D3D7EE
40%#2139ac66#A6B0DE
60%#2139ac99#7A88CD
80%#2139accc#4D61BD

Gradients from #2139ac

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, #324FD8, #2139ac 45%, #15246B);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #2139ac, #601C92);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #2139ac, #AC9421);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #4C65DD 0%, #2139ac 45%, #15246B 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F4F5FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #2AACD6 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #6726C6 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #15246B 0%, transparent 65%), #2139ac;

Monochromatic scale

Palettes built from #2139ac

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.

#2139ac 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

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 2.25:1 — lift it to #556DDE 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.

#2139ac, answered

What color is #2139ac?

#2139ac is a dark vivid blue, closest to Dark Slate Blue (ΔE2000 7.5). It sits at 230° on the hue wheel with 68% saturation and 40% lightness, which reads as cool.

What is the RGB value of #2139ac?

rgb(33, 57, 172) — 33 red, 57 green and 172 blue out of 255, or 12.9% / 22.4% / 67.5% by channel.

What is #2139ac in HSL and HSV?

hsl(230, 68%, 40%) and hsv(230, 81%, 67%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #2139ac a light or a dark color?

It is a dark color. Relative luminance is 0.0623 and perceived brightness is 29%, so white text on it reaches 9.35:1.

Should I use black or white text on #2139ac?

White. It scores 9.35:1 against #2139ac, versus 2.25:1 for black — AAA at any size.

Is #2139ac accessible on a white background?

#2139ac on white scores 9.35:1, which clears AAA at every size.

What is the complementary color of #2139ac?

#AC9421 sits directly opposite on the wheel. Softer options are the split-complements #AC4E21 and #7FAC21, which give the same contrast with far less vibration.

What colors go well with #2139ac?

For interface work: #F4F5FA as the surface, #C0C8ED for borders, #4B599B for secondary text, #B0721D as an accent and #15246B for hover and pressed states. For a palette, the analogous pair #217FAC and #4E21AC stays calm, while #AC9421 is the loudest partner.

What is #2139ac in CMYK for printing?

cmyk(81%, 67%, 0%, 33%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #2139ac 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 #3C21AC; nudged cooler, #1F51AE.

Which Tailwind color is closest to #2139ac?

The indigo family — its 500 step is #6366f1, ΔE2000 17.8 away. That is a visible difference, so define #2139ac as a custom token rather than reaching for the built-in.

How do I use #2139ac in Tailwind CSS?

Inline it as an arbitrary value with bg-[#2139ac] or text-[#2139ac], 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 #2139ac with 50% opacity?

rgba(33, 57, 172, 0.5), or #2139ac80 in eight-digit hex. Over white that composites to #909CD6; over black, #111D56.

Is #2139ac a web-safe color?

No. The nearest web-safe colour is #333399, ΔE2000 3.7 away. The palette only matters for legacy displays and some email clients now.

What does the color #2139ac 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 chroma the effect is amplified — it will dominate whatever sits beside it.

What gradient works with #2139ac?

The safest is same-hue elevation: linear-gradient(135deg, #324FD8, #2139ac 45%, #15246B). For more colour, a short hue run to #601C92 keeps it rich without turning muddy.

Work with #2139ac in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #2139ac at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.