What color is #666FCC?

#666FCC is a medium blue-violet. In RGB it is rgb(102, 111, 204), and in HSL hsl(235, 50%, 60%).

Is #666FCC accessible as text?

On white, #666FCC has a contrast ratio of 4.46:1 (fails WCAG AA for body text); on black it is 4.71:1 (passes). For text placed on #666FCC, use black for the best readability.

What is the closest Tailwind color to #666FCC?

The nearest Tailwind CSS token is sky-600 (#0084D1).

What colors go well with #666FCC?

#666FCC pairs cleanly with neutrals — cream, taupe, charcoal and cool grays — and with its complementary #CCC466. In UI, a softer accent is often easier to use than the exact complement. Explore the harmonies, shades, tints and ready-made palettes for #666FCC below.

Is #666FCC good for buttons?

#666FCC works well for buttons and highlights, but use black text on #666FCC — white text only reaches 4.46:1, below the 4.5:1 needed for normal-size labels.

Is #666FCC the same as CSS slateblue?

No — #666FCC is not the CSS named color slateblue, but slateblue (#6A5ACD) is the closest CSS named color.

#666FCC Color — HEX, RGB, HSL, Palette & Shades

Palettes built on #666FCC

Not just a swatch — here's how #666FCC works with other colors. Named schemes with #666FCC in its natural role, and a note on why the supporting colors balance it.

Coastal Morning Lead · 5 colors

Lead #666FCC Accent #A5C4C2 Surface #EAD5BF Secondary #9AA0A1 Anchor #22344A

Slate Blue opens this coastal palette with sea-glass and warm sand alongside it, grounded by driftwood grey and a deep-navy anchor.

Vintage Leather Lead · 5 colors

Lead #666FCC Secondary #7F4534 Surface #EED7C2 Accent #365247 Anchor #582239

Slate Blue plays the worn-leather lead, deepened by saddle brown and an oxblood anchor, softened by aged cream and cooled by a muted forest green.

Modern Café Dominant · 5 colors

Dominant #666FCC Anchor #3B2923 Surface #F3E1D2 Accent #769F7B Secondary #3C3734

Slate Blue anchors this café scheme as the warm mid-tone, lifted by latte cream and a muted sage accent and grounded by espresso brown and a warm charcoal.

Berry & Cream Lead · 5 colors

Lead #666FCC Surface #F6E5D8 Anchor #5B2142 Accent #E5C2C9 Secondary #322B2F

Slate Blue sits between cream and a deep berry here, softened by a blush accent and grounded by charcoal.

Minimal Editorial Surface · 5 colors

Surface #F8F4EF Accent #666FCC Secondary #9CA2C4 Support #9D9088 Ink #18140F

Slate Blue is the single accent in this high-contrast editorial system — set on near-white paper against near-black ink, with a warm grey and a desaturated tint of Slate Blue carrying the quiet middle.

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Color Lab

How #666FCC actually behaves in design work — read from its OKLCH lightness, chroma and hue, not just its raw numbers. Ten signals to help you decide where this color earns its place.

Warmth 21/100

Cool

Reads cool and recessive — calming, technical, good for trust-led UI.

Softness 44/100

Moderate

Middle-weight — neither delicate nor heavy.

Depth 43/100

Moderate

Mid depth — usable as an accent or a muted ground.

Naturalness 0/100

Very low

Reads engineered rather than organic — synthetic, digital.

Vintage feel 45/100

Moderate

A faint retro warmth without tipping into sepia.

Luxury 48/100

Moderate

Understated — leans refined without going austere.

Brand distinctiveness 38/100

Low

Recognisable but shares space with nearby hues.

UI accent fit 96/100

Very high

Strong interactive accent — visible and can carry a legible label.

Surface fit 17/100

Very low

Too saturated or mid-toned for big areas — keep it to accents.

Print safety 78/100

High

Reproduces faithfully in CMYK — safe for packaging and print.

Pairs with #666FCC

For UI

For branding

For interior

For fashion

People also use #666FCC with

Maya Blue Amethyst Dark Khaki Gainsboro Prussian Blue

UI roles & guardrails

Primary action Too mid-tone for a filled button — darken for the fill. AA Large

Body text Do not use for body copy on light surfaces. Avoid

Large display Fine for headings 24px+ on white. Pass

Background Pair with white text at 4.5:1. Use

Subtle surface Use #E3E4F2 for cards and hover fills. Tint 80

Avoid beside #8066CC — the hue gap is too small to read as intentional. Clash

In real applications

Not a swatch to memorise — a color to build with. Here is #666FCC at work across the surfaces designers actually ship.

Website / UI

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Dashboard

Revenue

$48.2k ▲ 12%

Brand

AVELINE

Studio

Poster

Nov 14 · 8PM

NIGHT
MARKET

Packaging

BLOOM

Botanical Wash

250 ml

Interior

Every model

Export

:root {
  --color-base: #666FCC;
  --color-base-rgb: 102 111 204;
  --color-base-oklch: oklch(57.9% 0.142 276.9);
  --color-50: #F3F4FC;
  --color-100: #E0E2F5;
  --color-200: #C2C5EB;
  --color-300: #979DD8;
  --color-400: #7077C2;
  --color-500: #4E56A6;
  --color-600: #424780;
  --color-700: #33375C;
  --color-800: #24263C;
  --color-900: #181925;
  --color-on-base: #141310;
}

// tailwind.config.js
colors: {
  slate-blue: {
    50: '#F3F4FC',
    100: '#E0E2F5',
    200: '#C2C5EB',
    300: '#979DD8',
    400: '#7077C2',
    500: '#4E56A6',
    600: '#424780',
    700: '#33375C',
    800: '#24263C',
    900: '#181925',
  },
}

$base: #666FCC;
$base-ink: #141310;
$base-50: #F3F4FC;
$base-100: #E0E2F5;
$base-200: #C2C5EB;
$base-300: #979DD8;
$base-400: #7077C2;
$base-500: #4E56A6;
$base-600: #424780;
$base-700: #33375C;
$base-800: #24263C;
$base-900: #181925;
$base-hover: #3D47B8;
$base-subtle: #D5D7EC;

{
    "color": {
        "base": {
            "value": "#666FCC",
            "type": "color"
        },
        "onBase": {
            "value": "#141310",
            "type": "color"
        },
        "scale": {
            "50": {
                "value": "#F3F4FC",
                "type": "color"
            },
            "100": {
                "value": "#E0E2F5",
                "type": "color"
            },
            "200": {
                "value": "#C2C5EB",
                "type": "color"
            },
            "300": {
                "value": "#979DD8",
                "type": "color"
            },
            "400": {
                "value": "#7077C2",
                "type": "color"
            },
            "500": {
                "value": "#4E56A6",
                "type": "color"
            },
            "600": {
                "value": "#424780",
                "type": "color"
            },
            "700": {
                "value": "#33375C",
                "type": "color"
            },
            "800": {
                "value": "#24263C",
                "type": "color"
            },
            "900": {
                "value": "#181925",
                "type": "color"
            }
        }
    }
}

Palettes built on #666FCC

Color Lab

Pairs with #666FCC

UI roles & guardrails

In real applications

Scales

Every model

Export