Color reference

#42C5F7 color reference

Clear Light Cyan-blue

This is a clear, light cyan-blue under the deterministic OKLCH hue, lightness, and chroma ranges. Its closest standardized CSS named color is Deep Sky Blue (#00BFFF), measured with straight-line OKLab distance.

Descriptive label
Clear Light Cyan-blue
Recommended text
Black · 10.56:1
Relative luminance
0.478062
Build a palette from #42C5F7 in Palette Generator Convert #42C5F7 in Color Converter
Formats UI preview Contrast 50–900 scale Harmonies Matches Related colors Color vision Exports

Copyable values

#42C5F7 in common color formats

Values are calculated from the same opaque sRGB color. Display rounding does not alter the internal calculations.

Color conversions for #42C5F7
Format Value Action
HEX #42C5F7
RGB rgb(66 197 247)
HSL hsl(197 91.88% 61.37%)
HSV hsv(197 73.28% 96.86%)
HWB hwb(197 25.88% 3.14%)
XYZ D65 color(xyz-d65 0.389988 0.478039 0.951705)
LAB lab(74.1111% -24.4659 -35.6804)
LCH lch(74.1111% 43.2628 235.5618)
OKLAB oklab(77.3662% -0.087834 -0.097758)
OKLCH oklch(77.3662% 0.131421 228.0607)

Real-world test

Try #42C5F7 on interface components

Preview the source as a primary action, subtle status, form treatment, and card surface. Persistent state controls help touch and keyboard users inspect the same normal, hover, and active colors.

Normal state uses #42C5F7 with black text at 10.56:1.

Action

Primary button

Use the controls above or point to and press the button to inspect its visual states.

Status

Subtle alert badge

A 12% source tint over white provides the background; readable text is selected separately.

Ready for review

Form

Border and focus ring

Source ring on white: 1.99:1 · does not meet the 3:1 non-text threshold where applicable.

Surface

Card component

The selected state becomes the card surface with its strongest black-or-white text pairing.

Design system Color decision ready Review states and surrounding surfaces before shipping.

Accessibility diagnostics

WCAG contrast for exact color pairs

Each result applies only to the named foreground, background, text size, and requirement. It is not a complete accessibility or component-conformance claim.

Source #42C5F7 Exact pair assessment Results for source text on white appear below.

On white

1.99:1

  • Fail AA normal text · 4.5:1
  • Fail AAA normal text · 7:1
  • Fail AA large text · 3:1
  • Fail UI/non-text where applicable · 3:1
Source #42C5F7 Exact pair assessment Results for source text on black appear below.

On black

10.56:1

  • Pass AA normal text · 4.5:1
  • Pass AAA normal text · 7:1
  • Pass AA large text · 3:1
  • Pass UI/non-text where applicable · 3:1

Use guidance

What this color may be suitable for

Not recommended

Normal-sized text

#42C5F7 does not reach 4.5:1 on white or Hue Codex paper, so it should not be used there for normal-sized text.

Needs a boundary

Controls and interface graphics

Against Hue Codex paper, the color reaches only 1.9:1. Use a contrasting border or another non-color boundary for meaningful controls and graphics.

Readable pairing available

Colored surface or button fill

Black text provides the stronger black/white pairing on #42C5F7 at 10.56:1. This validates only that text pair, not hover, focus, disabled, or adjacent-color states.

Distinctive accent

Palette role

Its OKLCH chroma of 0.1314 gives it enough visual presence for an accent or primary role when the tested foreground and neighboring colors pass.

Pair available

Color used as foreground

The stronger black/white background is black at 10.56:1. Always retest against the actual rendered background and text size.

Tested backgrounds

Foreground pairing comparison

#42C5F7 foreground contrast on tested backgrounds
Pair Background Contrast ratio
Black#000000 10.56:1
Hue Codex ink#10212B 8.29:1
White#FFFFFF 1.99:1
Hue Codex paper#FBFAF5 1.9:1
Soft neutral#F2EFE6 1.73:1
Check #42C5F7 on another background in Contrast Checker

Design-system starting point

A perceptual 50–900 reference scale

The source color is preserved at the nearest lightness step. Other swatches keep its OKLCH hue, moderate chroma toward the extremes, and reduce chroma only when needed to remain in sRGB.

50
100
200
300 #42C5F7 Source
400
500
600
700
800
900

This is a Hue Codex reference scale, not a claim that the values match Tailwind, Material, or another framework’s named palette.

Adjust the #42C5F7 scale in Tints, Shades & Tones

Color relationships

Complementary, analogous, and triadic colors

Hue rotations use OKLCH while preserving lightness and requested chroma. When a rotated result falls outside sRGB, chroma is reduced deterministically and disclosed.

Complementary

Source #42C5F7
Complement

Analogous

Source #42C5F7
Analogous −30°
Analogous +30° Chroma fitted to sRGB

Triadic

Source #42C5F7
Triad +120°
Triad +240°

Applied pairing

A small interface check

The source anchors the main action while the complement marks a secondary status. Contrast is selected separately for each fill.

Project color Clear Light Cyan-blue
Complement
Explore #42C5F7 in Color Harmonies

Distance matching

Closest standardized and framework colors

Matches use straight-line OKLab distance ×100. A smaller value means the coordinates are closer in this model; it is not a claim that two tokens are interchangeable in a design system.

CSS named color

Deep Sky Blue

#00BFFF

OKLab distance ×100: 3

Tailwind v4 default

sky-400

oklch(74.6% 0.16 232.661)

OKLab distance ×100: 4.14 · sRGB preview #00BCFF

Print boundary

Pantone match not estimated

Reliable print matching needs licensed reference data plus a defined ink, paper, profile, and viewing condition.

Read the print methodology

Color-vision screening

Approximate color-vision-deficiency views

These encoded-sRGB matrix previews are screening approximations. They help reveal possible color-only distinctions but do not reproduce every person’s vision or establish accessibility conformance.

Original#42C5F7
Approx.

Protanopia

Red-vision deficiency approximation

Original#42C5F7
Approx.

Deuteranopia

Green-vision deficiency approximation

Original#42C5F7
Approx.

Tritanopia

Blue-yellow deficiency approximation

Original#42C5F7
Approx.

Achromatopsia

Monochromatic-vision approximation

Test #42C5F7 with a complete palette in the CVD Simulator

Ready to use

Copy framework-ready color tokens

Exports preserve the source, readable foreground, and generated 50–900 scale. Tailwind v4 CSS-first and Tailwind v3 JavaScript-config formats are labeled separately.

CSS custom properties

Semantic aliases and the complete 50–900 scale.

:root {
  --color-primary: #42C5F7;
  --color-on-primary: #000000;
  --color-primary-oklch: oklch(77.3662% 0.131421 228.0607);
  --color-primary-50: #E9F8FF;
  --color-primary-100: #B3E7FF;
  --color-primary-200: #69D3FF;
  --color-primary-300: #42C5F7;
  --color-primary-400: #12A0CE;
  --color-primary-500: #0086AF;
  --color-primary-600: #006D8F;
  --color-primary-700: #005570;
  --color-primary-800: #003E53;
  --color-primary-900: #002837;
}

Tailwind v4 CSS-first theme

Current @theme syntax for bg-brand, text-brand, and scale utilities.

@import "tailwindcss";

@theme {
  --color-brand: #42C5F7;
  --color-brand-foreground: #000000;
  --color-brand-50: #E9F8FF;
  --color-brand-100: #B3E7FF;
  --color-brand-200: #69D3FF;
  --color-brand-300: #42C5F7;
  --color-brand-400: #12A0CE;
  --color-brand-500: #0086AF;
  --color-brand-600: #006D8F;
  --color-brand-700: #005570;
  --color-brand-800: #003E53;
  --color-brand-900: #002837;
}

Tailwind v3 / legacy config

CommonJS theme.extend.colors for JavaScript-config projects.

module.exports = {
  theme: {
    extend: {
      colors: {
        brand: {
          '50': '#E9F8FF',
          '100': '#B3E7FF',
          '200': '#69D3FF',
          '300': '#42C5F7',
          '400': '#12A0CE',
          '500': '#0086AF',
          '600': '#006D8F',
          '700': '#005570',
          '800': '#003E53',
          '900': '#002837',
          DEFAULT: '#42C5F7',
          foreground: '#000000',
        },
      },
    },
  },
};

Sass variables

Semantic source, foreground, OKLCH, and scale variables.

$color-primary: #42C5F7;
$color-on-primary: #000000;
$color-primary-oklch: oklch(77.3662% 0.131421 228.0607);
$color-primary-50: #E9F8FF;
$color-primary-100: #B3E7FF;
$color-primary-200: #69D3FF;
$color-primary-300: #42C5F7;
$color-primary-400: #12A0CE;
$color-primary-500: #0086AF;
$color-primary-600: #006D8F;
$color-primary-700: #005570;
$color-primary-800: #003E53;
$color-primary-900: #002837;

Modern color-mix()

Static fallbacks followed by OKLab tint and shade declarations.

:root {
  --color-primary: #42C5F7;
  --color-primary-tint: #69D3FF;
  --color-primary-tint: color-mix(in oklab, var(--color-primary) 72%, white);
  --color-primary-shade: #005570;
  --color-primary-shade: color-mix(in oklab, var(--color-primary) 82%, black);
}

JSON design data

Source formats, readable text, and the generated scale.

{
    "name": "Clear Light Cyan-blue",
    "hex": "#42C5F7",
    "rgb": "rgb(66 197 247)",
    "oklch": "oklch(77.3662% 0.131421 228.0607)",
    "recommendedText": "#000000",
    "scale": {
        "50": "#E9F8FF",
        "100": "#B3E7FF",
        "200": "#69D3FF",
        "300": "#42C5F7",
        "400": "#12A0CE",
        "500": "#0086AF",
        "600": "#006D8F",
        "700": "#005570",
        "800": "#003E53",
        "900": "#002837"
    }
}

Continue the decision

Use #42C5F7 in a complete workflow

Reference values are a starting point. Test the color in its real role, background, states, typography, and surrounding palette before shipping.

Adjust #42C5F7 in Color PickerStart with this exact color and white as the working background for role and accessibility decisions. Build a palette from #42C5F7 in Palette GeneratorUse this exact HEX as the seed for a deterministic, role-based palette. Check #42C5F7 on white in Contrast CheckerStart with this color as the foreground and white as the background, then test the real pair.