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blue · cool

#1b4dbb

a dark, vivid blue · cool · closest name: Royal Blue

Token name suggestion: Slate Cobalt

RGB
27, 77, 187
HSL
221°, 75%, 42%
CMYK
86, 59, 0, 27
Luminance
0.0913

#1b4dbb is a dark vivid blue, 221° on the wheel and 94/100 on the cool side. Put white text on it (7.43:1). As text it scores 7.43:1 on white — safe at any size. Nearest name is Royal Blue, nearest Tailwind family is indigo.

hsl(221 75% 42%)rgb(27 77 187)Base step 700AAA inkCool

At a glance

Every number on this page in one read: what #1b4dbb is made of, how bright it looks, and which way it leans.

Hex
#1b4dbb
Hue
221°
blue
Saturation
75%
vivid
Lightness
42%
dark
Brightness
73%
HSV value
Perceived
34%
weighted brightness
Luminance
0.0913
WCAG relative
Temperature
Cool
94/100 cool
Color family
Blue
Tone
Vivid
Best ink
White
7.43:1
Closest name
Royal Blue
ΔE2000 10.6
Chroma
67.6
LCH, 0–130ish
OKLCH L
0.460
perceptual lightness
Tailwind
indigo
500 · ΔE 13.6
Web-safe
#3366CC
nearest of 216
Where it sits
Hue221° of 360°
Saturation75%
Lightness42%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #1b4dbb.

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
Red3%
Green58%
Blue39%

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

Every format

HEX#1b4dbb
HEX (8-digit)#1b4dbbff
RGBrgb(27, 77, 187)
RGBArgba(27, 77, 187, 1)
HSLhsl(221, 75%, 42%)
HSV / HSBhsv(221, 86%, 73%)
HWBhwb(221 11% 27%)
CMYKcmyk(86%, 59%, 0%, 27%)
LABlab(36.2 26.2 -62.3)
LCHlch(36.2 67.6 292.8)
OKLCHoklch(0.460 0.182 262.9)
XYZ (D65)xyz(12.07, 9.13, 48.13)
Decimal1789371
Display P3color(display-p3 0.106 0.302 0.733)
Web-safe#3366CC

Copy-ready code

every platformclick to select
/* CSS */
color: #1b4dbb;
background-color: #1b4dbb;
/* CSS custom property */
--brand: #1b4dbb;
/* Tailwind (arbitrary) */
class="text-[#1b4dbb] bg-[#1b4dbb]"
/* SCSS */
$brand: #1b4dbb;
/* SwiftUI */
Color(red: 0.106, green: 0.302, blue: 0.733)
/* UIKit */
UIColor(red: 0.106, green: 0.302, blue: 0.733, alpha: 1)
/* Android XML */
<color name="brand">#1B4DBB</color>
/* Android Compose */
Color(0xFF1B4DBB)
/* Flutter */
Color(0xFF1B4DBB)
/* Python / OpenCV (BGR) */
(187, 77, 27)
/* Python / PIL (RGB) */
(27, 77, 187)
/* Java AWT */
new Color(27, 77, 187)
/* .NET */
Color.FromArgb(255, 27, 77, 187)
/* OpenGL / Unity (0–1) */
(0.1059f, 0.3020f, 0.7333f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{27,77,187}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #1b4dbb 85%, white);
border-color: color-mix(in oklab, #1b4dbb 40%, transparent);
/* theme-aware in one line */
color: light-dark(#102E6F, #D3DBEE);
/* relative colour syntax */
--hover: hsl(from #1b4dbb 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: #F3F6FC;
  --brand-100: #E7ECF9;
  --brand-200: #C8D6F4;
  --brand-300: #9DB7F1;
  --brand-400: #6C93EA;
  --brand-500: #3B6FE3;
  --brand-600: #1F58D6;
  --brand-700: #1b4dbb;
  --brand-800: #153B8F;
  --brand-900: #132D67;
  --brand-950: #0C1C41;
  --brand: #1b4dbb;
  --brand-ink: #ffffff;
  --brand-surface: #F4F6FA;
  --brand-border: #C0CEED;
  --brand-hover: #16409C;
  --brand-pressed: #12337D;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141924;
    --brand-ink: #D3DBEE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F3F6FC',
        100: '#E7ECF9',
        200: '#C8D6F4',
        300: '#9DB7F1',
        400: '#6C93EA',
        500: '#3B6FE3',
        600: '#1F58D6',
        700: '#1b4dbb',
        800: '#153B8F',
        900: '#132D67',
        950: '#0C1C41',
        DEFAULT: '#1b4dbb',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F3F6FC,
  '100': #E7ECF9,
  '200': #C8D6F4,
  '300': #9DB7F1,
  '400': #6C93EA,
  '500': #3B6FE3,
  '600': #1F58D6,
  '700': #1b4dbb,
  '800': #153B8F,
  '900': #132D67,
  '950': #0C1C41,
);
$brand-base: #1b4dbb;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F3F6FC", "$type": "color" },
      "100": { "$value": "#E7ECF9", "$type": "color" },
      "200": { "$value": "#C8D6F4", "$type": "color" },
      "300": { "$value": "#9DB7F1", "$type": "color" },
      "400": { "$value": "#6C93EA", "$type": "color" },
      "500": { "$value": "#3B6FE3", "$type": "color" },
      "600": { "$value": "#1F58D6", "$type": "color" },
      "700": { "$value": "#1b4dbb", "$type": "color" },
      "800": { "$value": "#153B8F", "$type": "color" },
      "900": { "$value": "#132D67", "$type": "color" },
      "950": { "$value": "#0C1C41", "$type": "color" }
    },
    "brandInk": { "$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 #1b4dbb · 7.43:1
Use #ffffffAAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 7.43:1 · recommended
AA pass · AA large pass · AAA pass
Aa
Black text · 2.83:1
AA fail · AA large fail · AAA fail
Reading the other direction: #1b4dbb as text scores 7.43:1 on white and 2.83:1 on black.
Best tinted ink on it, if plain black or white feels flat: #E9EFFC at 6.45:1.

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
#1b4dbb · 7.43:1
AA on whitealready passes
#1b4dbb
The quick fox
#1b4dbb · 7.43:1
AAA on whitealready passes
#1b4dbb
The quick fox
#3B6FE3 · 4.57:1
AA on black+14% L
#3B6FE3
The quick fox
#6C93EA · 7.00:1
AAA on black+25% L
#6C93EA

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #1B4DBB 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
#1b4dbb on white: 7.43:1
AA ✓ pass · AA-large · AAA
Aa
#1b4dbb on black: 2.83:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #1b4dbb as text on that neutral, and that neutral as text on #1b4dbb.

NeutralRatioBoth directions
White7.43:1AaAa
Slate 507.10:1AaAa
Slate 1006.78:1AaAa
Slate 2006.03:1AaAa
Slate 3005.01:1AaAa
Slate 4002.90:1AaAa
Slate 5001.56:1AaAa
Slate 6001.02:1AaAa
Slate 7001.39:1AaAa
Slate 8001.97:1AaAa
Slate 9002.40:1AaAa
Black2.83:1AaAa
Colour vision deficiency
true color
protanopia · #005DBF
deuteranopia · #004EB9
tritanopia · #00697C

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. #1b4dbb 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.

#F3F6FC
#E7ECF9
#C8D6F4
#9DB7F1
#6C93EA
#3B6FE3
#1F58D6
#1b4dbb
#153B8F
#132D67
#0C1C41
Base = 700Lightest = 50 · #F3F6FCDarkest = 950 · #0C1C41Text 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 0.045 262.9);
  --brand-100: oklch(0.94 0.073 262.9);
  --brand-200: oklch(0.88 0.109 262.9);
  --brand-300: oklch(0.80 0.142 262.9);
  --brand-400: oklch(0.72 0.167 262.9);
  --brand-500: oklch(0.64 0.182 262.9);
  --brand-600: oklch(0.56 0.182 262.9);
  --brand-700: oklch(0.48 0.171 262.9);
  --brand-800: oklch(0.40 0.153 262.9);
  --brand-900: oklch(0.32 0.127 262.9);
  --brand-950: oklch(0.24 0.100 262.9);
}

Colors that work with #1b4dbb

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#C0CEED
Hairlines and dividers
Muted text#4B649B
Captions on the surface
Accent#BF6117
Second voice, not a rival
Dark variant#102E6F
Hover, pressed, headers
Light variant#E9EFFC
Selected rows, tints
Dark surface#141924
Dark-mode background
Hover#16409C
One step down in lightness
Pressed#12337D
Two steps down
Disabled#8F9CB7
Chroma pulled out
Focus ring#1250D9
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 #1b4dbb

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
  • Weight58/100
  • 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#BB891B
Analogous left#1B9DBB
Analogous right#391BBB
Split-complement 1#BB391B
Split-complement 2#9DBB1B
Triadic 1#BB1B4D
Triadic 2#4DBB1B
Tetradic#BB1B9D
On the wheel
Base+30°−30°+120°+240°+180°221°

#1b4dbb sits at 221°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red10.6%
Green30.2%
Blue73.3%
R · 0–255
27
0x1b
G · 0–255
77
0x4d
B · 0–255
187
0xbb

CMYK percentages

Cyan85.6%
Magenta58.8%
Yellow0.0%
Key (black)26.7%

Total ink coverage is 171%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#1b4dbb text on a black background

contrast 2.83:1

Card sample

#1b4dbb text on a white background

contrast 7.43:1

Card sample

#1b4dbb on grey

6.78:1

#1b4dbb on its own surface

6.87:1

#1b4dbb on its dark surface

2.37:1

CSS3 live lab

Text font color

The quick brown fox

color: #1b4dbb;
Background color
Panel with #1b4dbb background
background-color: #1b4dbb;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #1b4dbb;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(27, 77, 187, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(27, 77, 187, 0.45);
Border & gradient
Gradient panel
border: 3px solid #1b4dbb;
background: linear-gradient(135deg, #1b4dbb, #541BBB);
Gradient text

Gradient headline

background: linear-gradient(90deg, #1b4dbb, #7C1BBB);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #1b4dbb;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #1b4dbb;
caret-color: #1b4dbb;
Left rule
Pull quote or callout
border-left: 4px solid #1b4dbb;
Ring + tint
Selected chip
background: #E9EFFC;
box-shadow: inset 0 0 0 2px #1b4dbb;
Conic badge
68%
background: conic-gradient(#1b4dbb 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #1b4dbb 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(27, 77, 187, 0.5)
rgb(27 77 187 / 50%)
#1b4dbb80
hsl(221 75% 42% / 50%)
color-mix(in srgb, #1b4dbb 50%, transparent)
Alpha8-digit hexFlat on white
10%#1b4dbb1a#E8EDF8
20%#1b4dbb33#D1DBF1
40%#1b4dbb66#A4B8E4
60%#1b4dbb99#7694D6
80%#1b4dbbcc#4971C9

Gradients from #1b4dbb

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, #3269E1, #1b4dbb 45%, #102E6F);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #1b4dbb, #5317A0);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #1b4dbb, #BB891B);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #4D7CE5 0%, #1b4dbb 45%, #102E6F 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%, #29CDE0 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #511FD6 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #102E6F 0%, transparent 65%), #1b4dbb;

Monochromatic scale

Palettes built from #1b4dbb

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.

#1b4dbb 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 2.83:1 — lift it to #3B6FE3 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.

#1b4dbb, answered

What color is #1b4dbb?

#1b4dbb is a dark vivid blue, closest to Royal Blue (ΔE2000 10.6). It sits at 221° on the hue wheel with 75% saturation and 42% lightness, which reads as cool.

What is the RGB value of #1b4dbb?

rgb(27, 77, 187) — 27 red, 77 green and 187 blue out of 255, or 10.6% / 30.2% / 73.3% by channel.

What is #1b4dbb in HSL and HSV?

hsl(221, 75%, 42%) and hsv(221, 86%, 73%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #1b4dbb a light or a dark color?

It is a dark color. Relative luminance is 0.0913 and perceived brightness is 34%, so white text on it reaches 7.43:1.

Should I use black or white text on #1b4dbb?

White. It scores 7.43:1 against #1b4dbb, versus 2.83:1 for black — AAA at any size.

Is #1b4dbb accessible on a white background?

#1b4dbb on white scores 7.43:1, which clears AAA at every size.

What is the complementary color of #1b4dbb?

#BB891B sits directly opposite on the wheel. Softer options are the split-complements #BB391B and #9DBB1B, which give the same contrast with far less vibration.

What colors go well with #1b4dbb?

For interface work: #F4F6FA as the surface, #C0CEED for borders, #4B649B for secondary text, #BF6117 as an accent and #102E6F for hover and pressed states. For a palette, the analogous pair #1B9DBB and #391BBB stays calm, while #BB891B is the loudest partner.

What is #1b4dbb in CMYK for printing?

cmyk(86%, 59%, 0%, 27%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #1b4dbb 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 #241BBB; nudged cooler, #1650A7.

Which Tailwind color is closest to #1b4dbb?

The indigo family — its 500 step is #6366f1, ΔE2000 13.6 away. That is a visible difference, so define #1b4dbb as a custom token rather than reaching for the built-in.

How do I use #1b4dbb in Tailwind CSS?

Inline it as an arbitrary value with bg-[#1b4dbb] or text-[#1b4dbb], 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 #1b4dbb with 50% opacity?

rgba(27, 77, 187, 0.5), or #1b4dbb80 in eight-digit hex. Over white that composites to #8DA6DD; over black, #0E275E.

Is #1b4dbb a web-safe color?

No. The nearest web-safe colour is #3366CC, ΔE2000 8.4 away. The palette only matters for legacy displays and some email clients now.

What does the color #1b4dbb 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 #1b4dbb?

The safest is same-hue elevation: linear-gradient(135deg, #3269E1, #1b4dbb 45%, #102E6F). For more colour, a short hue run to #5317A0 keeps it rich without turning muddy.

Work with #1b4dbb in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #1b4dbb at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.