What color is #183FBF?

#183FBF is a medium, vivid blue. In RGB it is rgb(24, 63, 191), and in HSL hsl(226, 78%, 42%).

Is #183FBF accessible as text?

On white, #183FBF has a contrast ratio of 8.39:1 (passes WCAG AA for body text); on black it is 2.50:1 (fails). For text placed on #183FBF, use white for the best readability.

What is the closest Tailwind color to #183FBF?

The nearest Tailwind CSS token is blue-800 (#193CB8).

What colors go well with #183FBF?

#183FBF pairs cleanly with neutrals — cream, taupe, charcoal and cool grays — and with its complementary #BF9818. In UI, a softer accent is often easier to use than the exact complement. Explore the harmonies, shades, tints and ready-made palettes for #183FBF below.

Is #183FBF good for buttons?

#183FBF works well for buttons and highlights, but use white text on #183FBF — black text only reaches 2.50:1, below the 4.5:1 needed for normal-size labels.

Is #183FBF the same as CSS mediumblue?

No — #183FBF is not the CSS named color mediumblue, but mediumblue (#0000CD) is the closest CSS named color.

#183FBF Color — HEX, RGB, HSL, Palette & Shades

Palettes built on #183FBF

Not just a swatch — here's how #183FBF works with other colors. Named schemes with #183FBF in its natural role, and a note on why the supporting colors balance it.

Tech Product Signal · 5 colors

Signal #183FBF Surface #14161A Highlight #F4F6F8 Secondary #5A6672 Accent #3D6ADD

Cobalt 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 Cobalt Blue.

Coastal Morning Lead · 5 colors

Lead #183FBF Accent #A5C4C2 Surface #DDDBBF Secondary #9AA0A1 Anchor #21344A

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

Berry & Cream Lead · 5 colors

Lead #183FBF Surface #F6E5D8 Anchor #5B2144 Accent #E5C2CA Secondary #322B2F

Cobalt 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 #183FBF Secondary #6579A4 Support #9D8F88 Ink #18140F

Cobalt 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 Cobalt Blue carrying the quiet middle.

Sunset Warmth Glow · 5 colors

Glow #183FBF Secondary #E76A75 Accent #F79251 Anchor #573B58 Surface #F7E7D7

Cobalt 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 #183FBF 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 9/100

Cool

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

Softness 28/100

Low

Firm and assertive — carries weight and contrast.

Depth 61/100

High

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

Naturalness 0/100

Very low

Reads engineered rather than organic — synthetic, digital.

Vintage feel 20/100

Very low

Clean and current — no dusty, aged cast.

Luxury 56/100

Moderate

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

Brand distinctiveness 79/100

High

Bold and ownable — memorable as a primary brand color.

UI accent fit 73/100

High

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

Surface fit 12/100

Very low

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

Print safety 63/100

High

Prints close, with a slight loss of vibrancy.

Pairs with #183FBF

For UI

For branding

For interior

For fashion

People also use #183FBF with

Picton Blue Grape Dijon 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 8.4:1. Use

Subtle surface Use #D1D9F2 for cards and hover fills. Tint 80

Avoid beside #2818BF — 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 #183FBF 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: #183FBF;
  --color-base-rgb: 24 63 191;
  --color-base-oklch: oklch(43.6% 0.204 265.1);
  --color-50: #F1F4FE;
  --color-100: #DAE2FB;
  --color-200: #B6C5F6;
  --color-300: #859DEA;
  --color-400: #5877DA;
  --color-500: #3656BF;
  --color-600: #304791;
  --color-700: #283767;
  --color-800: #1E2643;
  --color-900: #141929;
  --color-on-base: #FFFFFF;
}

// tailwind.config.js
colors: {
  cobalt-blue: {
    50: '#F1F4FE',
    100: '#DAE2FB',
    200: '#B6C5F6',
    300: '#859DEA',
    400: '#5877DA',
    500: '#3656BF',
    600: '#304791',
    700: '#283767',
    800: '#1E2643',
    900: '#141929',
  },
}

$base: #183FBF;
$base-ink: #FFFFFF;
$base-50: #F1F4FE;
$base-100: #DAE2FB;
$base-200: #B6C5F6;
$base-300: #859DEA;
$base-400: #5877DA;
$base-500: #3656BF;
$base-600: #304791;
$base-700: #283767;
$base-800: #1E2643;
$base-900: #141929;
$base-hover: #133299;
$base-subtle: #B8C5ED;

{
    "color": {
        "base": {
            "value": "#183FBF",
            "type": "color"
        },
        "onBase": {
            "value": "#FFFFFF",
            "type": "color"
        },
        "scale": {
            "50": {
                "value": "#F1F4FE",
                "type": "color"
            },
            "100": {
                "value": "#DAE2FB",
                "type": "color"
            },
            "200": {
                "value": "#B6C5F6",
                "type": "color"
            },
            "300": {
                "value": "#859DEA",
                "type": "color"
            },
            "400": {
                "value": "#5877DA",
                "type": "color"
            },
            "500": {
                "value": "#3656BF",
                "type": "color"
            },
            "600": {
                "value": "#304791",
                "type": "color"
            },
            "700": {
                "value": "#283767",
                "type": "color"
            },
            "800": {
                "value": "#1E2643",
                "type": "color"
            },
            "900": {
                "value": "#141929",
                "type": "color"
            }
        }
    }
}

Palettes built on #183FBF

Color Lab

Pairs with #183FBF

UI roles & guardrails

In real applications

Scales

Every model

Export