What color is #663ECC?

#663ECC is a medium indigo. In RGB it is rgb(102, 62, 204), and in HSL hsl(257, 58%, 52%).

Is #663ECC accessible as text?

On white, #663ECC has a contrast ratio of 6.72:1 (passes WCAG AA for body text); on black it is 3.13:1 (fails). For text placed on #663ECC, use white for the best readability.

What is the closest Tailwind color to #663ECC?

The nearest Tailwind CSS token is violet-700 (#7008E7).

What colors go well with #663ECC?

#663ECC pairs cleanly with neutrals — cream, taupe, charcoal and cool grays — and with its complementary #A3CC3E. In UI, a softer accent is often easier to use than the exact complement. Explore the harmonies, shades, tints and ready-made palettes for #663ECC below.

Is #663ECC good for buttons?

#663ECC works well for buttons and highlights, but use white text on #663ECC — black text only reaches 3.13:1, below the 4.5:1 needed for normal-size labels.

Is #663ECC the same as CSS slateblue?

No — #663ECC is not the CSS named color slateblue, but slateblue (#6A5ACD) is the closest CSS named color by perceptual color distance — it sits in a different color family, so treat it as a rough reference, not a match.

#663ECC Color — HEX, RGB, HSL, Palette & Shades

Palettes built on #663ECC

Not just a swatch — here's how #663ECC works with other colors. Named schemes with #663ECC in its natural role, and a note on why the supporting colors balance it.

Tech Product Signal · 5 colors

Signal #663ECC Surface #14161A Highlight #F4F6F8 Secondary #5B6672 Accent #866BEB

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 Slate Blue.

Berry & Cream Lead · 5 colors

Lead #663ECC Surface #F5E5D7 Anchor #5C2141 Accent #E5C2C8 Secondary #332B2F

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 #663ECC Secondary #8A84B4 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.

Coastal Morning Lead · 5 colors

Lead #663ECC Accent #A5C4C3 Surface #E9D6BF Secondary #9AA0A1 Anchor #22334A

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 #663ECC Secondary #E86B6E Accent #F5934B Anchor #583B57 Surface #F7E7D7

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 #663ECC 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 25/100

Cool

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

Softness 31/100

Low

Firm and assertive — carries weight and contrast.

Depth 54/100

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 24/100

Low

Clean and current — no dusty, aged cast.

Luxury 51/100

Moderate

Understated — leans refined without going austere.

Brand distinctiveness 80/100

High

Bold and ownable — memorable as a primary brand color.

UI accent fit 82/100

Very high

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

Surface fit 8/100

Very low

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

Print safety 72/100

High

Reproduces faithfully in CMYK — safe for packaging and print.

Pairs with #663ECC

For UI

For branding

For interior

For fashion

People also use #663ECC with

Glaucous Medium Orchid Yellow Green Gainsboro Russian Violet

UI roles & guardrails

Primary action Safe as a filled button with white label. AA

Body text Passes on white at 16px and above. Pass

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

Background Pair with white text at 6.7:1. Use

Subtle surface Use #E2DCF1 for cards and hover fills. Tint 80

Avoid beside #953ECC — 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 #663ECC 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: #663ECC;
  --color-base-rgb: 102 62 204;
  --color-base-oklch: oklch(49.6% 0.206 289.6);
  --color-50: #F5F2FC;
  --color-100: #E5DEF7;
  --color-200: #CCBFEE;
  --color-300: #A792DD;
  --color-400: #8469C9;
  --color-500: #6447AD;
  --color-600: #513D85;
  --color-700: #3D305F;
  --color-800: #2A233E;
  --color-900: #1B1726;
  --color-on-base: #FFFFFF;
}

// tailwind.config.js
colors: {
  slate-blue: {
    50: '#F5F2FC',
    100: '#E5DEF7',
    200: '#CCBFEE',
    300: '#A792DD',
    400: '#8469C9',
    500: '#6447AD',
    600: '#513D85',
    700: '#3D305F',
    800: '#2A233E',
    900: '#1B1726',
  },
}

$base: #663ECC;
$base-ink: #FFFFFF;
$base-50: #F5F2FC;
$base-100: #E5DEF7;
$base-200: #CCBFEE;
$base-300: #A792DD;
$base-400: #8469C9;
$base-500: #6447AD;
$base-600: #513D85;
$base-700: #3D305F;
$base-800: #2A233E;
$base-900: #1B1726;
$base-hover: #4F2DA8;
$base-subtle: #D3CAEA;

{
    "color": {
        "base": {
            "value": "#663ECC",
            "type": "color"
        },
        "onBase": {
            "value": "#FFFFFF",
            "type": "color"
        },
        "scale": {
            "50": {
                "value": "#F5F2FC",
                "type": "color"
            },
            "100": {
                "value": "#E5DEF7",
                "type": "color"
            },
            "200": {
                "value": "#CCBFEE",
                "type": "color"
            },
            "300": {
                "value": "#A792DD",
                "type": "color"
            },
            "400": {
                "value": "#8469C9",
                "type": "color"
            },
            "500": {
                "value": "#6447AD",
                "type": "color"
            },
            "600": {
                "value": "#513D85",
                "type": "color"
            },
            "700": {
                "value": "#3D305F",
                "type": "color"
            },
            "800": {
                "value": "#2A233E",
                "type": "color"
            },
            "900": {
                "value": "#1B1726",
                "type": "color"
            }
        }
    }
}