Is #636975 accessible for body text on white?

#636975 has a contrast ratio of 5.51:1 against white, which is sufficient for WCAG AA body text (4.5:1).

What is the complementary color of #636975?

The complement of #636975 is #756F63.

#636975 Slate

rgb(99, 105, 117)

Color conversions

HEX: #636975
RGB: rgb(99, 105, 117)
RGBA: rgba(99, 105, 117, 1)
HSL: hsl(220, 8%, 42%)
HSV / HSB: hsv(220, 15%, 46%)
CMYK: cmyk(15%, 10%, 0%, 54%)

Wide-gamut spaces

XYZ: xyz(13.407, 14.04, 18.83)
LAB: lab(44.29 0.41 -7.48)
LCH: lch(44.29 7.49 273.11)
OKLAB: oklab(51.98% -0.002 -0.0202)
OKLCH: oklch(51.98% 0.0203 264.38)
Nearest name: Slate

Shades, tints and tones

Shades

Tints

Tones

Color harmonies

Complementary

The hue directly opposite on the color wheel. Maximum contrast, ideal for a single accent against a dominant brand color.

Analogous

Neighbouring hues that share a temperature. The safest harmony for calm, cohesive interfaces.

Triadic

Three hues evenly spaced 120 degrees apart. Vibrant and balanced — use one as dominant and the other two sparingly.

Split Complementary

The complement split into two adjacent hues. Nearly the contrast of complementary with noticeably less tension.

Square (Tetradic)

Four hues at 90-degree intervals. A rich set for illustration, data visualisation, and category coding.

Rectangle (Tetradic)

Two complementary pairs offset by 60 degrees. Gives two warm and two cool options in one system.

Monochromatic

A single hue across five lightness levels. The foundation of most UI scales and the most accessible starting point.

Similar colors

Closest matches

Opacity variations

#6369751a

#63697533

#6369754d

#63697566

#63697580

#63697599

#636975b3

#636975cc

#636975e6

#636975ff

On white

5.51:1

Body text AA · Large text AA

On black

3.81:1

Body text AA Large · Large text AA

White-on-color contrast is 5.51:1.

Color blindness preview

Protanopia

No red cones — ~1% of men

Protanomaly

Reduced red sensitivity — ~1% of men

Deuteranopia

No green cones — ~1% of men

Deuteranomaly

Reduced green sensitivity — ~5% of men

Tritanopia

No blue cones — very rare

Tritanomaly

Reduced blue sensitivity — very rare

Achromatopsia

No color perception — ~1 in 30,000

Achromatomaly

Partial color perception — rare

Meaning, psychology and brand usage

The structural colour every interface actually runs on

Neutral grays carry no emotional charge, which is precisely their value: they let content and brand colour do the signalling. Their temperature matters more than designers expect — a cool gray beside a warm brand colour reads as a mistake.

Neutrality, professionalism, and precision. Overuse reads as noncommittal or unfinished.

Payne's gray, mixed rather than mined, became the painter's shortcut for atmospheric shadow. Swiss modernism turned systematic gray scales into a design methodology.

Build a full gray ramp before choosing a brand colour. Match the gray's temperature to the brand hue and reserve the darkest steps for type rather than large fills.

Common industries: Enterprise, Architecture, Automotive, Consulting, Hardware. Pairs well with a single saturated accent, warm white for text surfaces, near-black for hierarchy.

Code exports

CSS

:root {
  --color-slate: #636975;
  --color-slate-rgb: 99 105 117;
  --color-slate-hsl: 220 8% 42%;
  --color-slate-oklch: 51.98% 0.0203 264.38;
}

.element {
  color: #636975;
  background-color: hsl(220, 8%, 42%);
  border: 1px solid rgb(99 105 117 / 40%);
}

SCSS

$slate: #636975;
$slate-light: #b1b4ba;
$slate-dark: #32353b;

.element {
  color: $slate;
  background: rgba($slate, 0.12);

  &:hover {
    color: darken($slate, 8%);
  }
}

LESS

@slate: #636975;
@slate-light: lighten(@slate, 12%);
@slate-dark: darken(@slate, 12%);

.element {
  color: @slate;
  background: fade(@slate, 12%);
}

Tailwind CSS

/* Tailwind v4 — src/styles.css */
@theme {
  --color-slate-50: #e0e1e3;
  --color-slate-100: #d0d2d6;
  --color-slate-200: #c1c3c8;
  --color-slate-300: #a1a5ac;
  --color-slate-400: #828791;
  --color-slate-500: #636975;
  --color-slate-600: #595f69;
  --color-slate-700: #454a52;
  --color-slate-800: #32353b;
  --color-slate-900: #1e2023;
}

/* Usage */
<div class="bg-slate-500 text-slate-50 ring-slate-600" />

/* Arbitrary value, no config needed */
<div class="bg-[#636975]" />

Bootstrap

// Bootstrap 5 — _variables.scss (before importing bootstrap)
$slate: #636975;
$primary: $slate;

$theme-colors: map-merge($theme-colors, (
  "slate": $slate
));

// Generates .text-slate, .bg-slate, .btn-slate
@import "bootstrap/scss/bootstrap";

Flutter

import 'package:flutter/material.dart';

const Color slate = Color(0xFF636975);

// As a MaterialColor swatch
const MaterialColor slateSwatch = MaterialColor(0xFF636975, <int, Color>{
  50: Color(0xFFE0E1E3),
  100: Color(0xFFD0D2D6),
  200: Color(0xFFC1C3C8),
  300: Color(0xFFA1A5AC),
  400: Color(0xFF828791),
  500: Color(0xFF636975),
  600: Color(0xFF595F69),
  700: Color(0xFF454A52),
  800: Color(0xFF32353B),
  900: Color(0xFF1E2023),
});

Swift / SwiftUI

import SwiftUI

extension Color {
    /// #636975 — Slate
    static let slate = Color(
        red: 0.3882,
        green: 0.4118,
        blue: 0.4588
    )
}

// UIKit
extension UIColor {
    static let slate = UIColor(
        red: 0.3882,
        green: 0.4118,
        blue: 0.4588,
        alpha: 1.0
    )
}

Android

<!-- res/values/colors.xml -->
<resources>
    <color name="slate">#636975</color>
    <color name="slate_translucent">#80636975</color>
</resources>

<!-- Jetpack Compose -->
val Slate = Color(0xFF636975)

JavaScript

export const SLATE = {
  hex: "#636975",
  rgb: [99, 105, 117],
  hsl: [220, 8, 42],
  oklch: "oklch(51.98% 0.0203 264.38)",
};

JSON tokens

{
  "$schema": "https://design-tokens.org/schema.json",
  "slate": {
    "$type": "color",
    "$value": "#636975",
    "$description": "Slate — generated by ColorVerse AI"
  }
}