#665ccc
a balanced, vivid blue · cool · closest name: Slate Blue
Token name suggestion: True Harbour
#665ccc is a balanced vivid blue, 245° on the wheel and 80/100 on the cool side. Put white text on it (5.29:1). As text it scores 5.29:1 on white — safe at any size. Nearest name is Slate Blue, nearest Tailwind family is indigo.
At a glance
Every number on this page in one read: what #665ccc is made of, how bright it looks, and which way it leans.
Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #665ccc.
Reads cool. Warm and cool siblings keep the same lightness, so you can swap one in without redoing your contrast maths.
Green carries most of what the eye calls brightness — that is why WCAG weights it 0.7152.
Every format
| HEX | #665ccc |
| HEX (8-digit) | #665cccff |
| RGB | rgb(102, 92, 204) |
| RGBA | rgba(102, 92, 204, 1) |
| HSL | hsl(245, 52%, 58%) |
| HSV / HSB | hsv(245, 55%, 80%) |
| HWB | hwb(245 36% 20%) |
| CMYK | cmyk(50%, 55%, 0%, 20%) |
| LAB | lab(45.4 33.7 -57.1) |
| LCH | lch(45.4 66.3 300.5) |
| OKLCH | oklch(0.543 0.168 283.3) |
| XYZ (D65) | xyz(20.20, 14.84, 58.91) |
| Decimal | 6708428 |
| Display P3 | color(display-p3 0.400 0.361 0.800) |
| Web-safe | #6666CC |
Copy-ready code
/* CSS */
color: #665ccc;
background-color: #665ccc;
/* CSS custom property */
--brand: #665ccc;
/* Tailwind (arbitrary) */
class="text-[#665ccc] bg-[#665ccc]"
/* SCSS */
$brand: #665ccc;
/* SwiftUI */
Color(red: 0.400, green: 0.361, blue: 0.800)
/* UIKit */
UIColor(red: 0.400, green: 0.361, blue: 0.800, alpha: 1)
/* Android XML */
<color name="brand">#665CCC</color>
/* Android Compose */
Color(0xFF665CCC)
/* Flutter */
Color(0xFF665CCC)
/* Python / OpenCV (BGR) */
(204, 92, 102)
/* Python / PIL (RGB) */
(102, 92, 204)
/* Java AWT */
new Color(102, 92, 204)
/* .NET */
Color.FromArgb(255, 102, 92, 204)
/* OpenGL / Unity (0–1) */
(0.4000f, 0.3608f, 0.8000f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{102,92,204}/* mix without leaving CSS */ background: color-mix(in oklab, #665ccc 85%, white); border-color: color-mix(in oklab, #665ccc 40%, transparent); /* theme-aware in one line */ color: light-dark(#241E61, #D5D3EE); /* relative colour syntax */ --hover: hsl(from #665ccc h s calc(l - 7));
Design tokens
The same ramp in the four formats a team actually needs. Paste one and the whole palette lands with it.
:root {
--brand-50: #F5F4FA;
--brand-100: #EBE9F6;
--brand-200: #D1CFED;
--brand-300: #AFAAE4;
--brand-400: #877FD7;
--brand-500: #665ccc;
--brand-600: #463ABA;
--brand-700: #3A319B;
--brand-800: #2F277C;
--brand-900: #25205B;
--brand-950: #171439;
--brand: #665ccc;
--brand-ink: #ffffff;
--brand-surface: #F5F4FA;
--brand-border: #C5C1EC;
--brand-hover: #4C41C3;
--brand-pressed: #4036AB;
}
@media (prefers-color-scheme: dark) {
:root {
--brand-surface: #151424;
--brand-ink: #D5D3EE;
}
}theme: {
extend: {
colors: {
brand: {
50: '#F5F4FA',
100: '#EBE9F6',
200: '#D1CFED',
300: '#AFAAE4',
400: '#877FD7',
500: '#665ccc',
600: '#463ABA',
700: '#3A319B',
800: '#2F277C',
900: '#25205B',
950: '#171439',
DEFAULT: '#665ccc',
},
},
},
}$brand: (
'50': #F5F4FA,
'100': #EBE9F6,
'200': #D1CFED,
'300': #AFAAE4,
'400': #877FD7,
'500': #665ccc,
'600': #463ABA,
'700': #3A319B,
'800': #2F277C,
'900': #25205B,
'950': #171439,
);
$brand-base: #665ccc;
$brand-ink: #ffffff;
@function brand($step) { @return map-get($brand, $step); }{
"color": {
"brand": {
"50": { "$value": "#F5F4FA", "$type": "color" },
"100": { "$value": "#EBE9F6", "$type": "color" },
"200": { "$value": "#D1CFED", "$type": "color" },
"300": { "$value": "#AFAAE4", "$type": "color" },
"400": { "$value": "#877FD7", "$type": "color" },
"500": { "$value": "#665ccc", "$type": "color" },
"600": { "$value": "#463ABA", "$type": "color" },
"700": { "$value": "#3A319B", "$type": "color" },
"800": { "$value": "#2F277C", "$type": "color" },
"900": { "$value": "#25205B", "$type": "color" },
"950": { "$value": "#171439", "$type": "color" }
},
"brandInk": { "$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.
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.
Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #665CCC 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
Contrast is symmetric, so each row covers both directions: #665ccc as text on that neutral, and that neutral as text on #665ccc.
| Neutral | Ratio | Verdict | Both directions |
|---|---|---|---|
| White#ffffff | 5.29:1 | AAAA lgAAA | AaAa |
| Slate 50#f8fafc | 5.06:1 | AAAA lgAAA | AaAa |
| Slate 100#f1f5f9 | 4.83:1 | AAAA lgAAA | AaAa |
| Slate 200#e2e8f0 | 4.29:1 | AAAA lgAAA | AaAa |
| Slate 300#cbd5e1 | 3.56:1 | AAAA lgAAA | AaAa |
| Slate 400#94a3b8 | 2.06:1 | AAAA lgAAA | AaAa |
| Slate 500#64748b | 1.11:1 | AAAA lgAAA | AaAa |
| Slate 600#475569 | 1.43:1 | AAAA lgAAA | AaAa |
| Slate 700#334155 | 1.96:1 | AAAA lgAAA | AaAa |
| Slate 800#1e293b | 2.76:1 | AAAA lgAAA | AaAa |
| Slate 900#0f172a | 3.37:1 | AAAA lgAAA | AaAa |
| Black#000000 | 3.97:1 | AAAA lgAAA | AaAa |
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. #665ccc 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.
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.
:root {
--brand-50: oklch(0.97 0.042 283.3);
--brand-100: oklch(0.94 0.067 283.3);
--brand-200: oklch(0.88 0.101 283.3);
--brand-300: oklch(0.80 0.131 283.3);
--brand-400: oklch(0.72 0.154 283.3);
--brand-500: oklch(0.64 0.168 283.3);
--brand-600: oklch(0.56 0.168 283.3);
--brand-700: oklch(0.48 0.158 283.3);
--brand-800: oklch(0.40 0.141 283.3);
--brand-900: oklch(0.32 0.117 283.3);
--brand-950: oklch(0.24 0.092 283.3);
}Colors that work with #665ccc
Not a palette — a role sheet. Each swatch answers one question you will hit while building the component.
Surface, border, heading and body all derive from this one hue, so the screen stays coherent without a second palette.
Lightness flips, hue holds. The accent stays the anchor in both themes.
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.
Focus ring uses the light variant so the field still reads as one shape.
The file stays available for seven days. Download it before it expires.
How to use #665ccc
Derived from its contrast, chroma and lightness — not from taste.
- ✓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
- ⚠Full-page backgrounds — tiring over long sessions
- ⚠Pairing with a same-lightness hue — edges vibrate
Meaning and mood
What a colour in this family tends to signal, and how this particular chroma and lightness change the reading.
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 mid lightness keeps it versatile in both themes.
It is also the most crowded hue on the web. Distinctiveness has to come from your other choices.
- FormalityMedium
- EnergyMedium-high
- 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 | #C2CC5C | Directly opposite — maximum tension | |
| Analogous left | #5C8ACC | Neighbour, quieter | |
| Analogous right | #9E5CCC | Neighbour, quieter | |
| Split-complement 1 | #CC9E5C | Contrast without the clash | |
| Split-complement 2 | #8ACC5C | Contrast without the clash | |
| Triadic 1 | #CC665C | Even thirds — balanced and loud | |
| Triadic 2 | #5CCC66 | Even thirds — balanced and loud | |
| Tetradic | #CC5C8A | Fourth corner of the square scheme |
#665ccc sits at 245°. Every dot is a harmony position and links to its own page in the table alongside.
RGB percentages
CMYK percentages
Total ink coverage is 125%. Most commercial presses cap around 300% — above that, sheets stop drying properly.
Color previews
#665ccc text on a black background
contrast 3.97:1
#665ccc text on a white background
contrast 5.29:1
#665ccc on grey
4.83:1
#665ccc on its own surface
4.84:1
#665ccc on its dark surface
3.43:1
CSS3 live lab
The quick brown fox
color: #665ccc;
background-color: #665ccc;
Glowing headline
text-shadow: 2px 2px 8px #665ccc;
Soft neon halo
text-shadow: 0 0 14px rgba(102, 92, 204, 0.45);
box-shadow: 0 12px 32px -8px rgba(102, 92, 204, 0.45);
border: 3px solid #665ccc; background: linear-gradient(135deg, #665ccc, #B15CCC);
Gradient headline
background: linear-gradient(90deg, #665ccc, #CC5CCB); -webkit-background-clip: text; color: transparent;
outline: 2px solid #665ccc; outline-offset: 3px;
Marked up text
text-decoration-color: #665ccc; caret-color: #665ccc;
border-left: 4px solid #665ccc;
background: #EDECF9; box-shadow: inset 0 0 0 2px #665ccc;
background: conic-gradient(#665ccc 68%, #e2e8f0 0);
Transparency
What each alpha value actually composites to. The top row is #665ccc 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.
rgba(102, 92, 204, 0.5) rgb(102 92 204 / 50%) #665ccc80 hsl(245 52% 58% / 50%) color-mix(in srgb, #665ccc 50%, transparent)
| Alpha | 8-digit hex | Flat on white |
|---|---|---|
| 10% | #665ccc1a | #F0EFFA |
| 20% | #665ccc33 | #E0DEF5 |
| 40% | #665ccc66 | #C2BEEB |
| 60% | #665ccc99 | #A39DE0 |
| 80% | #665ccccc | #857DD6 |
Gradients from #665ccc
Six recipes, each built from this hex and shown with the exact CSS that produced it.
background: linear-gradient(135deg, #928ADB, #665ccc 45%, #241E61);
background: linear-gradient(120deg, #665ccc, #B045C5);
background: linear-gradient(90deg, #665ccc, #C2CC5C);
background: radial-gradient(120% 120% at 20% 0%, #A8A2E2 0%, #665ccc 45%, #241E61 100%);
background: linear-gradient(180deg, #F5F4FA, #ffffff);
background: radial-gradient(60% 60% at 15% 20%, #83ADD8 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #B473D3 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #241E61 0%, transparent 65%), #665ccc;
Monochromatic scale
Palettes built from #665ccc
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.
Closest color with a full write-up: Iris (#5a4fcf) — ΔE2000 4.2 away, with its history, psychology and brand usage.
#665ccc in the real world
Where a color in this family tends to land, and the interface roles it is usually asked to play.
Converts to four-color process without much drama. Proof it anyway.
Holds up across typical panel gamma. Still worth checking on an uncalibrated laptop, where mid-tones shift most.
Too dim on dark surfaces at 3.97:1 — lift it to #7168D0 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.
#665ccc, answered
What color is #665ccc?
#665ccc is a balanced vivid blue, closest to Slate Blue (ΔE2000 1.1). It sits at 245° on the hue wheel with 52% saturation and 58% lightness, which reads as cool.
What is the RGB value of #665ccc?
rgb(102, 92, 204) — 102 red, 92 green and 204 blue out of 255, or 40% / 36.1% / 80% by channel.
What is #665ccc in HSL and HSV?
hsl(245, 52%, 58%) and hsv(245, 55%, 80%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.
Is #665ccc a light or a dark color?
It is a dark color. Relative luminance is 0.1484 and perceived brightness is 44%, so white text on it reaches 5.29:1.
Should I use black or white text on #665ccc?
White. It scores 5.29:1 against #665ccc, versus 3.97:1 for black — AA at any size.
Is #665ccc accessible on a white background?
#665ccc on white scores 5.29:1, which clears AA at every size but not AAA.
What is the complementary color of #665ccc?
#C2CC5C sits directly opposite on the wheel. Softer options are the split-complements #CC9E5C and #8ACC5C, which give the same contrast with far less vibration.
What colors go well with #665ccc?
For interface work: #F5F4FA as the surface, #C5C1EC for borders, #524B9B for secondary text, #9F8D2D as an accent and #241E61 for hover and pressed states. For a palette, the analogous pair #5C8ACC and #9E5CCC stays calm, while #C2CC5C is the loudest partner.
What is #665ccc in CMYK for printing?
cmyk(50%, 55%, 0%, 20%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.
Is #665ccc warm or cool?
Cool — it scores 80 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #8F5CCC; nudged cooler, #5A7ACE.
Which Tailwind color is closest to #665ccc?
The indigo family — its 500 step is #6366f1, ΔE2000 6.2 away. That is a visible difference, so define #665ccc as a custom token rather than reaching for the built-in.
How do I use #665ccc in Tailwind CSS?
Inline it as an arbitrary value with bg-[#665ccc] or text-[#665ccc], 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 #665ccc with 50% opacity?
rgba(102, 92, 204, 0.5), or #665ccc80 in eight-digit hex. Over white that composites to #B3AEE6; over black, #332E66.
Is #665ccc a web-safe color?
No. The nearest web-safe colour is #6666CC, ΔE2000 3.3 away. The palette only matters for legacy displays and some email clients now.
What does the color #665ccc 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 #665ccc?
The safest is same-hue elevation: linear-gradient(135deg, #928ADB, #665ccc 45%, #241E61). For more colour, a short hue run to #B045C5 keeps it rich without turning muddy.
Work with #665ccc in the Color Lab
Every tool opens with this colour already loaded.
Every value on this page is computed from #665ccc at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.