What color is #1B40BB?

#1B40BB is a medium, vivid blue. In RGB it is rgb(27, 64, 187), and in HSL hsl(226, 75%, 42%).

Is #1B40BB accessible as text?

On white, #1B40BB has a contrast ratio of 8.41:1 (passes WCAG AA for body text); on black it is 2.50:1 (fails). For text placed on #1B40BB, use white for the best readability.

What is the closest Tailwind color to #1B40BB?

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

What colors go well with #1B40BB?

#1B40BB pairs cleanly with neutrals — cream, taupe, charcoal and cool grays — and with its complementary #BB961B. In UI, a softer accent is often easier to use than the exact complement. Explore the harmonies, shades, tints and ready-made palettes for #1B40BB below.

Is #1B40BB good for buttons?

#1B40BB works well for buttons and highlights, but use white text on #1B40BB — black text only reaches 2.50:1, below the 4.5:1 needed for normal-size labels.

Is #1B40BB the same as CSS mediumblue?

No — #1B40BB is not the CSS named color mediumblue, but mediumblue (#0000CD) is the closest CSS named color.

#1B40BB Color — HEX, RGB, HSL, Palette & Shades

Palettes built on #1B40BB

Not just a swatch — here's how #1B40BB works with other colors. Named schemes with #1B40BB in its natural role, and a note on why the supporting colors balance it.

Tech Product Signal · 5 colors

Signal #1B40BB Surface #14161A Highlight #F4F6F8 Secondary #5A6672 Accent #3F6AD9

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 #1B40BB 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 #1B40BB 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 #1B40BB Secondary #6578A2 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 #1B40BB Secondary #E86A75 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 #1B40BB 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 60/100

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 22/100

Low

Clean and current — no dusty, aged cast.

Luxury 57/100

Moderate

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

Brand distinctiveness 76/100

High

Bold and ownable — memorable as a primary brand color.

UI accent fit 75/100

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 64/100

High

Prints close, with a slight loss of vibrancy.

Pairs with #1B40BB

For UI

For branding

For interior

For fashion

People also use #1B40BB 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 #D1D9F1 for cards and hover fills. Tint 80

Avoid beside #2B1BBB — 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 #1B40BB 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: #1B40BB;
  --color-base-rgb: 27 64 187;
  --color-base-oklch: oklch(43.5% 0.197 265.3);
  --color-50: #F1F4FE;
  --color-100: #DAE2FB;
  --color-200: #B8C6F5;
  --color-300: #879EE8;
  --color-400: #5B78D7;
  --color-500: #3857BC;
  --color-600: #324890;
  --color-700: #293766;
  --color-800: #1E2742;
  --color-900: #141929;
  --color-on-base: #FFFFFF;
}

// tailwind.config.js
colors: {
  cobalt-blue: {
    50: '#F1F4FE',
    100: '#DAE2FB',
    200: '#B8C6F5',
    300: '#879EE8',
    400: '#5B78D7',
    500: '#3857BC',
    600: '#324890',
    700: '#293766',
    800: '#1E2742',
    900: '#141929',
  },
}

$base: #1B40BB;
$base-ink: #FFFFFF;
$base-50: #F1F4FE;
$base-100: #DAE2FB;
$base-200: #B8C6F5;
$base-300: #879EE8;
$base-400: #5B78D7;
$base-500: #3857BC;
$base-600: #324890;
$base-700: #293766;
$base-800: #1E2742;
$base-900: #141929;
$base-hover: #153396;
$base-subtle: #B9C5EC;

{
    "color": {
        "base": {
            "value": "#1B40BB",
            "type": "color"
        },
        "onBase": {
            "value": "#FFFFFF",
            "type": "color"
        },
        "scale": {
            "50": {
                "value": "#F1F4FE",
                "type": "color"
            },
            "100": {
                "value": "#DAE2FB",
                "type": "color"
            },
            "200": {
                "value": "#B8C6F5",
                "type": "color"
            },
            "300": {
                "value": "#879EE8",
                "type": "color"
            },
            "400": {
                "value": "#5B78D7",
                "type": "color"
            },
            "500": {
                "value": "#3857BC",
                "type": "color"
            },
            "600": {
                "value": "#324890",
                "type": "color"
            },
            "700": {
                "value": "#293766",
                "type": "color"
            },
            "800": {
                "value": "#1E2742",
                "type": "color"
            },
            "900": {
                "value": "#141929",
                "type": "color"
            }
        }
    }
}

Palettes built on #1B40BB

Color Lab

Pairs with #1B40BB

UI roles & guardrails

In real applications

Scales

Every model

Export