What color is #666AEA?

#666AEA is a light, vivid blue-violet. In RGB it is rgb(102, 106, 234), and in HSL hsl(238, 76%, 66%).

Is #666AEA accessible as text?

On white, #666AEA has a contrast ratio of 4.36:1 (fails WCAG AA for body text); on black it is 4.81:1 (passes). For text placed on #666AEA, use black for the best readability.

What is the closest Tailwind color to #666AEA?

The nearest Tailwind CSS token is indigo-500 (#615FFF).

What colors go well with #666AEA?

#666AEA pairs cleanly with neutrals — cream, taupe, charcoal and cool grays — and with its complementary #EAE666. In UI, a softer accent is often easier to use than the exact complement. Explore the harmonies, shades, tints and ready-made palettes for #666AEA below.

Is #666AEA good for buttons?

#666AEA works well for buttons and highlights, but use black text on #666AEA — white text only reaches 4.36:1, below the 4.5:1 needed for normal-size labels.

Is #666AEA the same as CSS mediumslateblue?

No — #666AEA is not the CSS named color mediumslateblue, but mediumslateblue (#7B68EE) is the closest CSS named color.

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

Palettes built on #666AEA

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

Tech Product Signal · 5 colors

Signal #666AEA Surface #14161A Highlight #F4F6F8 Secondary #5B6672 Accent #8993FF

Medium Slate Blue is the vivid signal in this product UI — on a near-black surface with cool white, a slate grey and a lighter tint of Medium Slate Blue.

Berry & Cream Lead · 5 colors

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

Medium 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 #666AEA Secondary #9DA4D1 Support #9D9088 Ink #18140F

Medium 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 Medium Slate Blue carrying the quiet middle.

Coastal Morning Lead · 5 colors

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

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

Sunset Warmth Glow · 5 colors

Glow #666AEA Secondary #E86A71 Accent #F6934E Anchor #583B57 Surface #F7E7D7

Medium Slate Blue glows at the center of this sunset palette, joined by coral and gold, deepened by a plum anchor and cooled with cream.

Build a working theme in the generator →

Color Lab

How #666AEA 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 16/100

Cool

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

Softness 38/100

Low

Middle-weight — neither delicate nor heavy.

Depth 44/100

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 29/100

Low

A faint retro warmth without tipping into sepia.

Luxury 44/100

Moderate

Understated — leans refined without going austere.

Brand distinctiveness 73/100

High

Bold and ownable — memorable as a primary brand color.

UI accent fit 85/100

Very high

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

Surface fit 16/100

Very low

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

Print safety 70/100

High

Reproduces faithfully in CMYK — safe for packaging and print.

Pairs with #666AEA

For UI

For branding

For interior

For fashion

People also use #666AEA with

Light Sky Blue Medium Orchid Naples Yellow 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 4.4:1. Use

Subtle surface Use #E4E5F7 for cards and hover fills. Tint 80

Avoid beside #8E66EA — 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 #666AEA 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: #666AEA;
  --color-base-rgb: 102 106 234;
  --color-base-oklch: oklch(58.9% 0.189 277.5);
  --color-50: #F1F1FE;
  --color-100: #DADBFB;
  --color-200: #B7B9F5;
  --color-300: #878AE9;
  --color-400: #5A5ED8;
  --color-500: #373CBD;
  --color-600: #323590;
  --color-700: #292B66;
  --color-800: #1E1F43;
  --color-900: #141529;
  --color-on-base: #141310;
}

// tailwind.config.js
colors: {
  medium-slate-blue: {
    50: '#F1F1FE',
    100: '#DADBFB',
    200: '#B7B9F5',
    300: '#878AE9',
    400: '#5A5ED8',
    500: '#373CBD',
    600: '#323590',
    700: '#292B66',
    800: '#1E1F43',
    900: '#141529',
  },
}

$base: #666AEA;
$base-ink: #141310;
$base-50: #F1F1FE;
$base-100: #DADBFB;
$base-200: #B7B9F5;
$base-300: #878AE9;
$base-400: #5A5ED8;
$base-500: #373CBD;
$base-600: #323590;
$base-700: #292B66;
$base-800: #1E1F43;
$base-900: #141529;
$base-hover: #2B31E2;
$base-subtle: #D6D7F4;

{
    "color": {
        "base": {
            "value": "#666AEA",
            "type": "color"
        },
        "onBase": {
            "value": "#141310",
            "type": "color"
        },
        "scale": {
            "50": {
                "value": "#F1F1FE",
                "type": "color"
            },
            "100": {
                "value": "#DADBFB",
                "type": "color"
            },
            "200": {
                "value": "#B7B9F5",
                "type": "color"
            },
            "300": {
                "value": "#878AE9",
                "type": "color"
            },
            "400": {
                "value": "#5A5ED8",
                "type": "color"
            },
            "500": {
                "value": "#373CBD",
                "type": "color"
            },
            "600": {
                "value": "#323590",
                "type": "color"
            },
            "700": {
                "value": "#292B66",
                "type": "color"
            },
            "800": {
                "value": "#1E1F43",
                "type": "color"
            },
            "900": {
                "value": "#141529",
                "type": "color"
            }
        }
    }
}