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blue · cool

#643fe7

a balanced, electric blue · cool · closest name: Blue Violet

Token name suggestion: Atlas Sapphire

RGB
100, 63, 231
HSL
253°, 78%, 58%
CMYK
57, 73, 0, 9
Luminance
0.1203

#643fe7 is a balanced electric blue, 253° on the wheel and 76/100 on the cool side. Put white text on it (6.16:1). As text it scores 6.16:1 on white — safe at any size. Nearest name is Blue Violet, nearest Tailwind family is violet.

hsl(253 78% 58%)rgb(100 63 231)Base step 500AA inkCool

At a glance

Every number on this page in one read: what #643fe7 is made of, how bright it looks, and which way it leans.

Hex
#643fe7
Hue
253°
blue
Saturation
78%
electric
Lightness
58%
balanced
Brightness
91%
HSV value
Perceived
42%
weighted brightness
Luminance
0.1203
WCAG relative
Temperature
Cool
76/100 cool
Color family
Blue
Tone
Electric
Best ink
White
6.16:1
Closest name
Blue Violet
ΔE2000 6.1
Chroma
98.0
LCH, 0–130ish
OKLCH L
0.519
perceptual lightness
Tailwind
violet
500 · ΔE 10.2
Web-safe
#6633FF
nearest of 216
Where it sits
Hue253° of 360°
Saturation78%
Lightness58%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #643fe7.

Temperature
Warm ← → Cool76% 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
Red23%
Green30%
Blue48%

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

Every format

HEX#643fe7
HEX (8-digit)#643fe7ff
RGBrgb(100, 63, 231)
RGBArgba(100, 63, 231, 1)
HSLhsl(253, 78%, 58%)
HSV / HSBhsv(253, 73%, 91%)
HWBhwb(253 25% 9%)
CMYKcmyk(57%, 73%, 0%, 9%)
LABlab(41.3 57.6 -79.3)
LCHlch(41.3 98.0 306.0)
OKLCHoklch(0.519 0.236 284.7)
XYZ (D65)xyz(21.45, 12.03, 76.78)
Decimal6569959
Display P3color(display-p3 0.392 0.247 0.906)
Web-safe#6633FF

Copy-ready code

every platformclick to select
/* CSS */
color: #643fe7;
background-color: #643fe7;
/* CSS custom property */
--brand: #643fe7;
/* Tailwind (arbitrary) */
class="text-[#643fe7] bg-[#643fe7]"
/* SCSS */
$brand: #643fe7;
/* SwiftUI */
Color(red: 0.392, green: 0.247, blue: 0.906)
/* UIKit */
UIColor(red: 0.392, green: 0.247, blue: 0.906, alpha: 1)
/* Android XML */
<color name="brand">#643FE7</color>
/* Android Compose */
Color(0xFF643FE7)
/* Flutter */
Color(0xFF643FE7)
/* Python / OpenCV (BGR) */
(231, 63, 100)
/* Python / PIL (RGB) */
(100, 63, 231)
/* Java AWT */
new Color(100, 63, 231)
/* .NET */
Color.FromArgb(255, 100, 63, 231)
/* OpenGL / Unity (0–1) */
(0.3922f, 0.2471f, 0.9059f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{100,63,231}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #643fe7 85%, white);
border-color: color-mix(in oklab, #643fe7 40%, transparent);
/* theme-aware in one line */
color: light-dark(#240E71, #D9D3EE);
/* relative colour syntax */
--hover: hsl(from #643fe7 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: #F5F3FC;
  --brand-100: #EBE6F9;
  --brand-200: #D1C7F5;
  --brand-300: #AE9BF3;
  --brand-400: #8669EC;
  --brand-500: #643fe7;
  --brand-600: #451BDA;
  --brand-700: #3A17B5;
  --brand-800: #2E1291;
  --brand-900: #251169;
  --brand-950: #170B42;
  --brand: #643fe7;
  --brand-ink: #ffffff;
  --brand-surface: #F6F4FA;
  --brand-border: #CAC0ED;
  --brand-hover: #4A1FE3;
  --brand-pressed: #3F19C6;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #171424;
    --brand-ink: #D9D3EE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F5F3FC',
        100: '#EBE6F9',
        200: '#D1C7F5',
        300: '#AE9BF3',
        400: '#8669EC',
        500: '#643fe7',
        600: '#451BDA',
        700: '#3A17B5',
        800: '#2E1291',
        900: '#251169',
        950: '#170B42',
        DEFAULT: '#643fe7',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F5F3FC,
  '100': #EBE6F9,
  '200': #D1C7F5,
  '300': #AE9BF3,
  '400': #8669EC,
  '500': #643fe7,
  '600': #451BDA,
  '700': #3A17B5,
  '800': #2E1291,
  '900': #251169,
  '950': #170B42,
);
$brand-base: #643fe7;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F5F3FC", "$type": "color" },
      "100": { "$value": "#EBE6F9", "$type": "color" },
      "200": { "$value": "#D1C7F5", "$type": "color" },
      "300": { "$value": "#AE9BF3", "$type": "color" },
      "400": { "$value": "#8669EC", "$type": "color" },
      "500": { "$value": "#643fe7", "$type": "color" },
      "600": { "$value": "#451BDA", "$type": "color" },
      "700": { "$value": "#3A17B5", "$type": "color" },
      "800": { "$value": "#2E1291", "$type": "color" },
      "900": { "$value": "#251169", "$type": "color" },
      "950": { "$value": "#170B42", "$type": "color" }
    },
    "brandInk": { "$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 #643fe7 · 6.16:1
Use #ffffffAA at every size, AAA for large text only.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 6.16:1 · recommended
AA pass · AA large pass · AAA fail
Aa
Black text · 3.41:1
AA fail · AA large pass · AAA fail
Reading the other direction: #643fe7 as text scores 6.16:1 on white and 3.41:1 on black.
Best tinted ink on it, if plain black or white feels flat: #EDE8FC at 5.15:1.

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
#643fe7 · 6.16:1
AA on whitealready passes
#643fe7
The quick fox
#5931E5 · 7.01:1
AAA on white−3% L
#5931E5
The quick fox
#7D5EEB · 4.67:1
AA on black+7% L
#7D5EEB
The quick fox
#9E87F0 · 7.18:1
AAA on black+16% L
#9E87F0

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #643FE7 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
#643fe7 on white: 6.16:1
AA ✓ pass · AA-large · AAA
Aa
#643fe7 on black: 3.41:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #643fe7 as text on that neutral, and that neutral as text on #643fe7.

NeutralRatioBoth directions
White6.16:1AaAa
Slate 505.89:1AaAa
Slate 1005.63:1AaAa
Slate 2005.00:1AaAa
Slate 3004.15:1AaAa
Slate 4002.40:1AaAa
Slate 5001.30:1AaAa
Slate 6001.23:1AaAa
Slate 7001.68:1AaAa
Slate 8002.37:1AaAa
Slate 9002.90:1AaAa
Black3.41:1AaAa
Colour vision deficiency
true color
protanopia · #0066EC
deuteranopia · #005CE4
tritanopia · #1E6D90

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. #643fe7 is pinned to step 500; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F5F3FC
#EBE6F9
#D1C7F5
#AE9BF3
#8669EC
#643fe7
#451BDA
#3A17B5
#2E1291
#251169
#170B42
Base = 500Lightest = 50 · #F5F3FCDarkest = 950 · #170B42Text 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 0.059 284.7);
  --brand-100: oklch(0.94 0.094 284.7);
  --brand-200: oklch(0.88 0.142 284.7);
  --brand-300: oklch(0.80 0.184 284.7);
  --brand-400: oklch(0.72 0.217 284.7);
  --brand-500: oklch(0.64 0.236 284.7);
  --brand-600: oklch(0.56 0.236 284.7);
  --brand-700: oklch(0.48 0.222 284.7);
  --brand-800: oklch(0.40 0.198 284.7);
  --brand-900: oklch(0.32 0.165 284.7);
  --brand-950: oklch(0.24 0.130 284.7);
}

Colors that work with #643fe7

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#F6F4FA
Tinted page background
Border#CAC0ED
Hairlines and dividers
Muted text#5C4B9B
Captions on the surface
Accent#B9B513
Second voice, not a rival
Dark variant#240E71
Hover, pressed, headers
Light variant#EDE8FC
Selected rows, tints
Dark surface#171424
Dark-mode background
Hover#4A1FE3
One step down in lightness
Pressed#3F19C6
Two steps down
Disabled#C5C0D6
Chroma pulled out
Focus ring#6D47F3
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 #643fe7

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
  • Brand accents, badges and data highlights
  • Chart series and data categories
Use with care
  • Full-page backgrounds — tiring over long sessions
  • 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 mid lightness keeps it versatile in both themes.

Worth knowing

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

Reads as
  • FormalityLow
  • EnergyHigh
  • Weight42/100
  • 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#C2E73F
Analogous left#3F6EE7
Analogous right#B83FE7
Split-complement 1#E7B83F
Split-complement 2#6EE73F
Triadic 1#E7643F
Triadic 2#3FE764
Tetradic#E73F6E
On the wheel
Base+30°−30°+120°+240°+180°253°

#643fe7 sits at 253°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red39.2%
Green24.7%
Blue90.6%
R · 0–255
100
0x64
G · 0–255
63
0x3f
B · 0–255
231
0xe7

CMYK percentages

Cyan56.7%
Magenta72.7%
Yellow0.0%
Key (black)9.4%

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

Color previews

#643fe7 text on a black background

contrast 3.41:1

Card sample

#643fe7 text on a white background

contrast 6.16:1

Card sample

#643fe7 on grey

5.63:1

#643fe7 on its own surface

5.65:1

#643fe7 on its dark surface

2.93:1

CSS3 live lab

Text font color

The quick brown fox

color: #643fe7;
Background color
Panel with #643fe7 background
background-color: #643fe7;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #643fe7;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(100, 63, 231, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(100, 63, 231, 0.45);
Border & gradient
Gradient panel
border: 3px solid #643fe7;
background: linear-gradient(135deg, #643fe7, #D43FE7);
Gradient text

Gradient headline

background: linear-gradient(90deg, #643fe7, #E73FD0);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #643fe7;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #643fe7;
caret-color: #643fe7;
Left rule
Pull quote or callout
border-left: 4px solid #643fe7;
Ring + tint
Selected chip
background: #EDE8FC;
box-shadow: inset 0 0 0 2px #643fe7;
Conic badge
68%
background: conic-gradient(#643fe7 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #643fe7 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(100, 63, 231, 0.5)
rgb(100 63 231 / 50%)
#643fe780
hsl(253 78% 58% / 50%)
color-mix(in srgb, #643fe7 50%, transparent)
Alpha8-digit hexFlat on white
10%#643fe71a#F0ECFD
20%#643fe733#E0D9FA
40%#643fe766#C1B2F5
60%#643fe799#A28CF1
80%#643fe7cc#8365EC

Gradients from #643fe7

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, #9075EE, #643fe7 45%, #240E71);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #643fe7, #DE24E4);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #643fe7, #C2E73F);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #A690F1 0%, #643fe7 45%, #240E71 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F6F4FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #6C9BED 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #CE5AEA 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #240E71 0%, transparent 65%), #643fe7;

Monochromatic scale

Palettes built from #643fe7

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.

#643fe7 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

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 3.41:1 — lift it to #7D5EEB 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.

#643fe7, answered

What color is #643fe7?

#643fe7 is a balanced electric blue, closest to Blue Violet (ΔE2000 6.1). It sits at 253° on the hue wheel with 78% saturation and 58% lightness, which reads as cool.

What is the RGB value of #643fe7?

rgb(100, 63, 231) — 100 red, 63 green and 231 blue out of 255, or 39.2% / 24.7% / 90.6% by channel.

What is #643fe7 in HSL and HSV?

hsl(253, 78%, 58%) and hsv(253, 73%, 91%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #643fe7 a light or a dark color?

It is a dark color. Relative luminance is 0.1203 and perceived brightness is 42%, so white text on it reaches 6.16:1.

Should I use black or white text on #643fe7?

White. It scores 6.16:1 against #643fe7, versus 3.41:1 for black — AA at any size.

Is #643fe7 accessible on a white background?

#643fe7 on white scores 6.16:1, which clears AA at every size but not AAA.

What is the complementary color of #643fe7?

#C2E73F sits directly opposite on the wheel. Softer options are the split-complements #E7B83F and #6EE73F, which give the same contrast with far less vibration.

What colors go well with #643fe7?

For interface work: #F6F4FA as the surface, #CAC0ED for borders, #5C4B9B for secondary text, #B9B513 as an accent and #240E71 for hover and pressed states. For a palette, the analogous pair #3F6EE7 and #B83FE7 stays calm, while #C2E73F is the loudest partner.

What is #643fe7 in CMYK for printing?

cmyk(57%, 73%, 0%, 9%). 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 #643fe7 warm or cool?

Cool — it scores 76 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #A13FE7; nudged cooler, #3D56E9.

Which Tailwind color is closest to #643fe7?

The violet family — its 500 step is #8b5cf6, ΔE2000 10.2 away. That is a visible difference, so define #643fe7 as a custom token rather than reaching for the built-in.

How do I use #643fe7 in Tailwind CSS?

Inline it as an arbitrary value with bg-[#643fe7] or text-[#643fe7], 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 #643fe7 with 50% opacity?

rgba(100, 63, 231, 0.5), or #643fe780 in eight-digit hex. Over white that composites to #B29FF3; over black, #322074.

Is #643fe7 a web-safe color?

No. The nearest web-safe colour is #6633FF, ΔE2000 3 away. The palette only matters for legacy displays and some email clients now.

What does the color #643fe7 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 #643fe7?

The safest is same-hue elevation: linear-gradient(135deg, #9075EE, #643fe7 45%, #240E71). For more colour, a short hue run to #DE24E4 keeps it rich without turning muddy.

Work with #643fe7 in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #643fe7 at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.