What color is #042FA5?

#042FA5 is a dark, vivid blue. In RGB it is rgb(4, 47, 165), and in HSL hsl(224, 95%, 33%).

Is #042FA5 accessible as text?

On white, #042FA5 has a contrast ratio of 10.74:1 (passes WCAG AA for body text); on black it is 1.96:1 (fails). For text placed on #042FA5, use white for the best readability.

What is the closest Tailwind color to #042FA5?

The nearest Tailwind CSS token is blue-900 (#1C398E).

What colors go well with #042FA5?

#042FA5 pairs cleanly with neutrals — cream, taupe, charcoal and cool grays — and with its complementary #A47904. In UI, a softer accent is often easier to use than the exact complement. Explore the harmonies, shades, tints and ready-made palettes for #042FA5 below.

Is #042FA5 good for buttons?

#042FA5 works well for buttons and highlights, but use white text on #042FA5 — black text only reaches 1.96:1, below the 4.5:1 needed for normal-size labels.

Is #042FA5 the same as CSS mediumblue?

No — #042FA5 is not the CSS named color mediumblue, but mediumblue (#0000CD) is the closest CSS named color.

#042FA5 Color — HEX, RGB, HSL, Palette & Shades

Palettes built on #042FA5

Not just a swatch — here's how #042FA5 works with other colors. Named schemes with #042FA5 in its natural role, and a note on why the supporting colors balance it.

Luxury Packaging Feature · 5 colors

Feature #042FA5 Anchor #141210 Accent #ACAE53 Secondary #242933 Surface #F0EEE3

Klein Blue carries the depth in this luxury scheme, offset by a brass accent and near-black and held together by a deep neutral and an off-white surface.

Tech Product Signal · 5 colors

Signal #042FA5 Surface #14161A Highlight #F4F6F8 Secondary #5A6672 Accent #2C59C3

Klein 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 Klein Blue.

Moody Editorial Color · 5 colors

Color #042FA5 Anchor #2A2A2E Secondary #6E6E74 Surface #E9E7DA Accent #1F0C60

Klein Blue adds the colour to this moody editorial scheme — charcoal and a mid-grey around it, a bone highlight, and a muted jewel accent drawn from Klein Blue.

Coastal Morning Lead · 5 colors

Lead #042FA5 Accent #A5C4C1 Surface #DDDBBF Secondary #9AA0A1 Anchor #21344A

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

Minimal Editorial Surface · 5 colors

Surface #F8F4EF Accent #042FA5 Secondary #54688F Support #9D8F88 Ink #18140F

Klein 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 Klein Blue carrying the quiet middle.

Build a working theme in the generator →

Color Lab

How #042FA5 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 8/100

Cool

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

Softness 25/100

Low

Firm and assertive — carries weight and contrast.

Depth 66/100

High

Deep and grounding — anchors a layout, strong dark-mode base.

Naturalness 0/100

Very low

Reads engineered rather than organic — synthetic, digital.

Vintage feel 21/100

Low

Clean and current — no dusty, aged cast.

Luxury 62/100

High

Restrained and premium — deep, quiet, high-end packaging and fashion.

Brand distinctiveness 74/100

High

Bold and ownable — memorable as a primary brand color.

UI accent fit 60/100

Moderate

Workable accent with care around contrast.

Surface fit 15/100

Very low

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

Print safety 64/100

High

Prints close, with a slight loss of vibrancy.

Pairs with #042FA5

For UI

For branding

For interior

For fashion

People also use #042FA5 with

Carolina Blue Zaffre Olive Brown Gainsboro Charcoal

UI roles & guardrails

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

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 10.7:1. Use

Subtle surface Use #C5D2F4 for cards and hover fills. Tint 80

Avoid beside #0F04A4 — 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 #042FA5 at work across the surfaces designers actually ship.

Website / UI

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Build faster.

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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: #042FA5;
  --color-base-rgb: 4 47 165;
  --color-base-oklch: oklch(37.7% 0.192 263.7);
  --color-50: #F0F4FE;
  --color-100: #D8E2FD;
  --color-200: #B1C5FC;
  --color-300: #7A9BF5;
  --color-400: #4A74E8;
  --color-500: #2753CE;
  --color-600: #26459C;
  --color-700: #21366E;
  --color-800: #1A2647;
  --color-900: #12192B;
  --color-on-base: #FFFFFF;
}

// tailwind.config.js
colors: {
  klein-blue: {
    50: '#F0F4FE',
    100: '#D8E2FD',
    200: '#B1C5FC',
    300: '#7A9BF5',
    400: '#4A74E8',
    500: '#2753CE',
    600: '#26459C',
    700: '#21366E',
    800: '#1A2647',
    900: '#12192B',
  },
}

$base: #042FA5;
$base-ink: #FFFFFF;
$base-50: #F0F4FE;
$base-100: #D8E2FD;
$base-200: #B1C5FC;
$base-300: #7A9BF5;
$base-400: #4A74E8;
$base-500: #2753CE;
$base-600: #26459C;
$base-700: #21366E;
$base-800: #1A2647;
$base-900: #12192B;
$base-hover: #032583;
$base-subtle: #A7BAF1;

{
    "color": {
        "base": {
            "value": "#042FA5",
            "type": "color"
        },
        "onBase": {
            "value": "#FFFFFF",
            "type": "color"
        },
        "scale": {
            "50": {
                "value": "#F0F4FE",
                "type": "color"
            },
            "100": {
                "value": "#D8E2FD",
                "type": "color"
            },
            "200": {
                "value": "#B1C5FC",
                "type": "color"
            },
            "300": {
                "value": "#7A9BF5",
                "type": "color"
            },
            "400": {
                "value": "#4A74E8",
                "type": "color"
            },
            "500": {
                "value": "#2753CE",
                "type": "color"
            },
            "600": {
                "value": "#26459C",
                "type": "color"
            },
            "700": {
                "value": "#21366E",
                "type": "color"
            },
            "800": {
                "value": "#1A2647",
                "type": "color"
            },
            "900": {
                "value": "#12192B",
                "type": "color"
            }
        }
    }
}

Palettes built on #042FA5

Color Lab

Pairs with #042FA5

UI roles & guardrails

In real applications

Scales

Every model

Export