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blue · cool

#331ab8

a dark, electric blue · cool · closest name: Medium Blue

Token name suggestion: Dusk Denim

RGB
51, 26, 184
HSL
250°, 75%, 41%
CMYK
72, 86, 0, 28
Luminance
0.0490

#331ab8 is a dark electric blue, 250° on the wheel and 78/100 on the cool side. Put white text on it (10.60:1). As text it scores 10.60:1 on white — safe at any size. Nearest name is Medium Blue, nearest Tailwind family is indigo.

hsl(250 75% 41%)rgb(51 26 184)Base step 700AAA inkCool

At a glance

Every number on this page in one read: what #331ab8 is made of, how bright it looks, and which way it leans.

Hex
#331ab8
Hue
250°
blue
Saturation
75%
electric
Lightness
41%
dark
Brightness
72%
HSV value
Perceived
28%
weighted brightness
Luminance
0.0490
WCAG relative
Temperature
Cool
78/100 cool
Color family
Blue
Tone
Electric
Best ink
White
10.60:1
Closest name
Medium Blue
ΔE2000 3.4
Chroma
94.9
LCH, 0–130ish
OKLCH L
0.391
perceptual lightness
Tailwind
indigo
500 · ΔE 21.3
Web-safe
#3333CC
nearest of 216
Where it sits
Hue250° of 360°
Saturation75%
Lightness41%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #331ab8.

Temperature
Warm ← → Cool78% 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
Red14%
Green15%
Blue71%

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

Every format

HEX#331ab8
HEX (8-digit)#331ab8ff
RGBrgb(51, 26, 184)
RGBArgba(51, 26, 184, 1)
HSLhsl(250, 75%, 41%)
HSV / HSBhsv(249, 86%, 72%)
HWBhwb(250 10% 28%)
CMYKcmyk(72%, 86%, 0%, 28%)
LABlab(26.4 56.0 -76.6)
LCHlch(26.4 94.9 306.2)
OKLCHoklch(0.391 0.222 275.8)
XYZ (D65)xyz(10.38, 4.90, 45.74)
Decimal3349176
Display P3color(display-p3 0.200 0.102 0.722)
Web-safe#3333CC

Copy-ready code

every platformclick to select
/* CSS */
color: #331ab8;
background-color: #331ab8;
/* CSS custom property */
--brand: #331ab8;
/* Tailwind (arbitrary) */
class="text-[#331ab8] bg-[#331ab8]"
/* SCSS */
$brand: #331ab8;
/* SwiftUI */
Color(red: 0.200, green: 0.102, blue: 0.722)
/* UIKit */
UIColor(red: 0.200, green: 0.102, blue: 0.722, alpha: 1)
/* Android XML */
<color name="brand">#331AB8</color>
/* Android Compose */
Color(0xFF331AB8)
/* Flutter */
Color(0xFF331AB8)
/* Python / OpenCV (BGR) */
(184, 26, 51)
/* Python / PIL (RGB) */
(51, 26, 184)
/* Java AWT */
new Color(51, 26, 184)
/* .NET */
Color.FromArgb(255, 51, 26, 184)
/* OpenGL / Unity (0–1) */
(0.2000f, 0.1020f, 0.7216f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{51,26,184}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #331ab8 85%, white);
border-color: color-mix(in oklab, #331ab8 40%, transparent);
/* theme-aware in one line */
color: light-dark(#1F1070, #D7D3EE);
/* relative colour syntax */
--hover: hsl(from #331ab8 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: #F4F3FC;
  --brand-100: #EAE7F9;
  --brand-200: #CFC8F4;
  --brand-300: #AA9DF1;
  --brand-400: #806CEA;
  --brand-500: #553AE3;
  --brand-600: #3C1ED6;
  --brand-700: #331ab8;
  --brand-800: #28148F;
  --brand-900: #201368;
  --brand-950: #140C41;
  --brand: #331ab8;
  --brand-ink: #ffffff;
  --brand-surface: #F5F4FA;
  --brand-border: #C7C0ED;
  --brand-hover: #2A1699;
  --brand-pressed: #22117A;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #161424;
    --brand-ink: #D7D3EE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F4F3FC',
        100: '#EAE7F9',
        200: '#CFC8F4',
        300: '#AA9DF1',
        400: '#806CEA',
        500: '#553AE3',
        600: '#3C1ED6',
        700: '#331ab8',
        800: '#28148F',
        900: '#201368',
        950: '#140C41',
        DEFAULT: '#331ab8',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F4F3FC,
  '100': #EAE7F9,
  '200': #CFC8F4,
  '300': #AA9DF1,
  '400': #806CEA,
  '500': #553AE3,
  '600': #3C1ED6,
  '700': #331ab8,
  '800': #28148F,
  '900': #201368,
  '950': #140C41,
);
$brand-base: #331ab8;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F4F3FC", "$type": "color" },
      "100": { "$value": "#EAE7F9", "$type": "color" },
      "200": { "$value": "#CFC8F4", "$type": "color" },
      "300": { "$value": "#AA9DF1", "$type": "color" },
      "400": { "$value": "#806CEA", "$type": "color" },
      "500": { "$value": "#553AE3", "$type": "color" },
      "600": { "$value": "#3C1ED6", "$type": "color" },
      "700": { "$value": "#331ab8", "$type": "color" },
      "800": { "$value": "#28148F", "$type": "color" },
      "900": { "$value": "#201368", "$type": "color" },
      "950": { "$value": "#140C41", "$type": "color" }
    },
    "brandInk": { "$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 #331ab8 · 10.60:1
Use #ffffffAAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 10.60:1 · recommended
AA pass · AA large pass · AAA pass
Aa
Black text · 1.98:1
AA fail · AA large fail · AAA fail
Reading the other direction: #331ab8 as text scores 10.60:1 on white and 1.98:1 on black.
Best tinted ink on it, if plain black or white feels flat: #ECE9FC at 8.90:1.

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
#331ab8 · 10.60:1
AA on whitealready passes
#331ab8
The quick fox
#331ab8 · 10.60:1
AAA on whitealready passes
#331ab8
The quick fox
#755FE8 · 4.56:1
AA on black+23% L
#755FE8
The quick fox
#9887EE · 7.04:1
AAA on black+32% L
#9887EE

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #331AB8 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
#331ab8 on white: 10.60:1
AA ✓ pass · AA-large · AAA
Aa
#331ab8 on black: 1.98:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #331ab8 as text on that neutral, and that neutral as text on #331ab8.

NeutralRatioBoth directions
White10.60:1AaAa
Slate 5010.13:1AaAa
Slate 1009.68:1AaAa
Slate 2008.60:1AaAa
Slate 3007.14:1AaAa
Slate 4004.14:1AaAa
Slate 5002.23:1AaAa
Slate 6001.40:1AaAa
Slate 7001.02:1AaAa
Slate 8001.38:1AaAa
Slate 9001.68:1AaAa
Black1.98:1AaAa
Colour vision deficiency
true color
protanopia · #0045BC
deuteranopia · #0038B5
tritanopia · #004F6D

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. #331ab8 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.

#F4F3FC
#EAE7F9
#CFC8F4
#AA9DF1
#806CEA
#553AE3
#3C1ED6
#331ab8
#28148F
#201368
#140C41
Base = 700Lightest = 50 · #F4F3FCDarkest = 950 · #140C41Text 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 0.056 275.8);
  --brand-100: oklch(0.94 0.089 275.8);
  --brand-200: oklch(0.88 0.133 275.8);
  --brand-300: oklch(0.80 0.173 275.8);
  --brand-400: oklch(0.72 0.205 275.8);
  --brand-500: oklch(0.64 0.222 275.8);
  --brand-600: oklch(0.56 0.222 275.8);
  --brand-700: oklch(0.48 0.209 275.8);
  --brand-800: oklch(0.40 0.187 275.8);
  --brand-900: oklch(0.32 0.156 275.8);
  --brand-950: oklch(0.24 0.122 275.8);
}

Colors that work with #331ab8

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#F5F4FA
Tinted page background
Border#C7C0ED
Hairlines and dividers
Muted text#574B9B
Captions on the surface
Accent#B7A815
Second voice, not a rival
Dark variant#1F1070
Hover, pressed, headers
Light variant#ECE9FC
Selected rows, tints
Dark surface#161424
Dark-mode background
Hover#2A1699
One step down in lightness
Pressed#22117A
Two steps down
Disabled#938DB6
Chroma pulled out
Focus ring#3011D5
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 #331ab8

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.

At this chroma the association is amplified — it will dominate anything placed beside it, so give it space and use it sparingly. 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
  • EnergyHigh
  • Weight59/100
  • 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#9FB81A
Analogous left#1A50B8
Analogous right#821AB8
Split-complement 1#B8821A
Split-complement 2#50B81A
Triadic 1#B8331A
Triadic 2#1AB833
Tetradic#B81A50
On the wheel
Base+30°−30°+120°+240°+180°250°

#331ab8 sits at 250°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red20.0%
Green10.2%
Blue72.2%
R · 0–255
51
0x33
G · 0–255
26
0x1a
B · 0–255
184
0xb8

CMYK percentages

Cyan72.3%
Magenta85.9%
Yellow0.0%
Key (black)27.8%

Total ink coverage is 186%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#331ab8 text on a black background

contrast 1.98:1

Card sample

#331ab8 text on a white background

contrast 10.60:1

Card sample

#331ab8 on grey

9.68:1

#331ab8 on its own surface

9.70:1

#331ab8 on its dark surface

1.71:1

CSS3 live lab

Text font color

The quick brown fox

color: #331ab8;
Background color
Panel with #331ab8 background
background-color: #331ab8;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #331ab8;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(51, 26, 184, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(51, 26, 184, 0.45);
Border & gradient
Gradient panel
border: 3px solid #331ab8;
background: linear-gradient(135deg, #331ab8, #9C1AB8);
Gradient text

Gradient headline

background: linear-gradient(90deg, #331ab8, #B81AAC);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #331ab8;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #331ab8;
caret-color: #331ab8;
Left rule
Pull quote or callout
border-left: 4px solid #331ab8;
Ring + tint
Selected chip
background: #ECE9FC;
box-shadow: inset 0 0 0 2px #331ab8;
Conic badge
68%
background: conic-gradient(#331ab8 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #331ab8 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(51, 26, 184, 0.5)
rgb(51 26 184 / 50%)
#331ab880
hsl(250 75% 41% / 50%)
color-mix(in srgb, #331ab8 50%, transparent)
Alpha8-digit hexFlat on white
10%#331ab81a#EBE8F8
20%#331ab833#D6D1F1
40%#331ab866#ADA3E3
60%#331ab899#8576D4
80%#331ab8cc#5C48C6

Gradients from #331ab8

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, #4A2EE1, #331ab8 45%, #1F1070);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #331ab8, #91169D);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #331ab8, #9FB81A);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #6149E5 0%, #331ab8 45%, #1F1070 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F5F4FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #2575E0 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #A41ED3 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #1F1070 0%, transparent 65%), #331ab8;

Monochromatic scale

Palettes built from #331ab8

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.

#331ab8 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

Sits outside most CMYK gamuts — expect a duller press result, or specify a spot ink.

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 1.98:1 — lift it to #755FE8 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.

#331ab8, answered

What color is #331ab8?

#331ab8 is a dark electric blue, closest to Medium Blue (ΔE2000 3.4). It sits at 250° on the hue wheel with 75% saturation and 41% lightness, which reads as cool.

What is the RGB value of #331ab8?

rgb(51, 26, 184) — 51 red, 26 green and 184 blue out of 255, or 20% / 10.2% / 72.2% by channel.

What is #331ab8 in HSL and HSV?

hsl(250, 75%, 41%) and hsv(249, 86%, 72%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #331ab8 a light or a dark color?

It is a dark color. Relative luminance is 0.0490 and perceived brightness is 28%, so white text on it reaches 10.60:1.

Should I use black or white text on #331ab8?

White. It scores 10.60:1 against #331ab8, versus 1.98:1 for black — AAA at any size.

Is #331ab8 accessible on a white background?

#331ab8 on white scores 10.60:1, which clears AAA at every size.

What is the complementary color of #331ab8?

#9FB81A sits directly opposite on the wheel. Softer options are the split-complements #B8821A and #50B81A, which give the same contrast with far less vibration.

What colors go well with #331ab8?

For interface work: #F5F4FA as the surface, #C7C0ED for borders, #574B9B for secondary text, #B7A815 as an accent and #1F1070 for hover and pressed states. For a palette, the analogous pair #1A50B8 and #821AB8 stays calm, while #9FB81A is the loudest partner.

What is #331ab8 in CMYK for printing?

cmyk(72%, 86%, 0%, 28%). This is a screen-to-ink approximation — a color this saturated sits outside most CMYK gamuts and will print duller than it looks here.

Is #331ab8 warm or cool?

Cool — it scores 78 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #6D1AB8; nudged cooler, #1839BA.

Which Tailwind color is closest to #331ab8?

The indigo family — its 500 step is #6366f1, ΔE2000 21.3 away. That is a visible difference, so define #331ab8 as a custom token rather than reaching for the built-in.

How do I use #331ab8 in Tailwind CSS?

Inline it as an arbitrary value with bg-[#331ab8] or text-[#331ab8], 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 #331ab8 with 50% opacity?

rgba(51, 26, 184, 0.5), or #331ab880 in eight-digit hex. Over white that composites to #998DDC; over black, #1A0D5C.

Is #331ab8 a web-safe color?

No. The nearest web-safe colour is #3333CC, ΔE2000 5.7 away. The palette only matters for legacy displays and some email clients now.

What does the color #331ab8 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 #331ab8?

The safest is same-hue elevation: linear-gradient(135deg, #4A2EE1, #331ab8 45%, #1F1070). For more colour, a short hue run to #91169D keeps it rich without turning muddy.

Work with #331ab8 in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #331ab8 at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.