What color is #183D40?

#183D40 is a very dark cyan. In RGB it is rgb(24, 61, 64), and in HSL hsl(185, 45%, 17%).

Is #183D40 accessible as text?

On white, #183D40 has a contrast ratio of 11.80:1 (passes WCAG AA for body text); on black it is 1.78:1 (fails). For text placed on #183D40, use white for the best readability.

What is the closest Tailwind color to #183D40?

The nearest Tailwind CSS token is cyan-950 (#053345).

What colors go well with #183D40?

#183D40 pairs cleanly with neutrals — cream, taupe, charcoal and cool grays — and with its complementary #3F1B18. In UI, a softer accent is often easier to use than the exact complement. Explore the harmonies, shades, tints and ready-made palettes for #183D40 below.

Is #183D40 good for buttons?

#183D40 works well for buttons and highlights, but use white text on #183D40 — black text only reaches 1.78:1, below the 4.5:1 needed for normal-size labels.

Is #183D40 the same as CSS darkslategray?

No — #183D40 is not the CSS named color darkslategray, but darkslategray (#2F4F4F) is the closest CSS named color.

#183D40 Color — HEX, RGB, HSL, Palette & Shades

Palettes built on #183D40

Not just a swatch — here's how #183D40 works with other colors. Named schemes with #183D40 in its natural role, and a note on why the supporting colors balance it.

Coastal Morning Lead · 5 colors

Lead #183D40 Accent #A6C4BE Surface #DFDABE Secondary #9AA0A0 Anchor #1D3549

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

Nordic Calm Accent · 5 colors

Accent #183D40 Secondary #AEB4B8 Surface #F1F2F0 Support #7A94A5 Anchor #2E3236

Gunmetal Gray keeps this Nordic scheme quiet — cool greys and a soft white around it, a muted-blue support and a charcoal anchor.

Tech Product Signal · 5 colors

Signal #183D40 Surface #14161A Highlight #F4F6F8 Secondary #596771 Accent #3D5D60

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

Vintage Leather Lead · 5 colors

Lead #183D40 Secondary #715017 Surface #E3DCC0 Accent #395143 Anchor #552340

Gunmetal Gray plays the worn-leather lead, deepened by saddle brown and an oxblood anchor, softened by aged cream and cooled by a muted forest green.

Minimal Editorial Surface · 5 colors

Surface #F6F4EF Accent #183D40 Secondary #535F60 Support #979286 Ink #16140F

Gunmetal Gray 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 Gunmetal Gray carrying the quiet middle.

Build a working theme in the generator →

Color Lab

How #183D40 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 39/100

Neutral

Balanced temperature — flexible, sits between warm and cool schemes.

Softness 34/100

Low

Middle-weight — neither delicate nor heavy.

Depth 63/100

High

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

Naturalness 5/100

Very low

Reads engineered rather than organic — synthetic, digital.

Vintage feel 32/100

Low

A faint retro warmth without tipping into sepia.

Luxury 66/100

High

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

Brand distinctiveness 16/100

Very low

Quiet and neutral — a supporting tone, not a signature.

UI accent fit 35/100

Low

Workable accent with care around contrast.

Surface fit 50/100

Moderate

Usable as a tinted surface in measured doses.

Print safety 89/100

Very high

Reproduces faithfully in CMYK — safe for packaging and print.

Pairs with #183D40

For UI

For branding

For interior

For fashion

People also use #183D40 with

Hunter Green Prussian Blue Oxblood Platinum Dark Slate Gray

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 11.8:1. Use

Subtle surface Use #C7E0E2 for cards and hover fills. Tint 80

Avoid beside #182F3F — 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 #183D40 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: #183D40;
  --color-base-rgb: 24 61 64;
  --color-base-oklch: oklch(33.5% 0.042 202.5);
  --color-50: #F4FAFB;
  --color-100: #E1F3F4;
  --color-200: #C4E5E8;
  --color-300: #9BD0D5;
  --color-400: #74B8BE;
  --color-500: #539BA2;
  --color-600: #45787D;
  --color-700: #35575A;
  --color-800: #26393B;
  --color-900: #192425;
  --color-on-base: #FFFFFF;
}

// tailwind.config.js
colors: {
  gunmetal-gray: {
    50: '#F4FAFB',
    100: '#E1F3F4',
    200: '#C4E5E8',
    300: '#9BD0D5',
    400: '#74B8BE',
    500: '#539BA2',
    600: '#45787D',
    700: '#35575A',
    800: '#26393B',
    900: '#192425',
  },
}

$base: #183D40;
$base-ink: #FFFFFF;
$base-50: #F4FAFB;
$base-100: #E1F3F4;
$base-200: #C4E5E8;
$base-300: #9BD0D5;
$base-400: #74B8BE;
$base-500: #539BA2;
$base-600: #45787D;
$base-700: #35575A;
$base-800: #26393B;
$base-900: #192425;
$base-hover: #133032;
$base-subtle: #AAD2D5;

{
    "color": {
        "base": {
            "value": "#183D40",
            "type": "color"
        },
        "onBase": {
            "value": "#FFFFFF",
            "type": "color"
        },
        "scale": {
            "50": {
                "value": "#F4FAFB",
                "type": "color"
            },
            "100": {
                "value": "#E1F3F4",
                "type": "color"
            },
            "200": {
                "value": "#C4E5E8",
                "type": "color"
            },
            "300": {
                "value": "#9BD0D5",
                "type": "color"
            },
            "400": {
                "value": "#74B8BE",
                "type": "color"
            },
            "500": {
                "value": "#539BA2",
                "type": "color"
            },
            "600": {
                "value": "#45787D",
                "type": "color"
            },
            "700": {
                "value": "#35575A",
                "type": "color"
            },
            "800": {
                "value": "#26393B",
                "type": "color"
            },
            "900": {
                "value": "#192425",
                "type": "color"
            }
        }
    }
}