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cyan · cool

#42abda

a balanced, vivid cyan · cool · closest name: Deep Sky Blue

Token name suggestion: Signal Teal

RGB
66, 171, 218
HSL
199°, 67%, 56%
CMYK
70, 22, 0, 15
Luminance
0.3535

#42abda is a balanced vivid cyan, 199° on the wheel and 95/100 on the cool side. Put black text on it (8.07:1). As text it scores 2.60:1 on white — use #207CA5 instead. Nearest name is Deep Sky Blue, nearest Tailwind family is sky.

hsl(199 67% 56%)rgb(66 171 218)Base step 500AAA inkCool

At a glance

Every number on this page in one read: what #42abda is made of, how bright it looks, and which way it leans.

Hex
#42abda
Hue
199°
cyan
Saturation
67%
vivid
Lightness
56%
balanced
Brightness
85%
HSV value
Perceived
61%
weighted brightness
Luminance
0.3535
WCAG relative
Temperature
Cool
95/100 cool
Color family
Cyan
Tone
Vivid
Best ink
Black
8.07:1
Closest name
Deep Sky Blue
ΔE2000 6.2
Chroma
35.9
LCH, 0–130ish
OKLCH L
0.701
perceptual lightness
Tailwind
sky
500 · ΔE 4.5
Web-safe
#3399CC
nearest of 216
Where it sits
Hue199° of 360°
Saturation67%
Lightness56%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #42abda.

Temperature
Warm ← → Cool95% cool

Reads cool. Warm and cool siblings keep the same lightness, so you can swap one in without redoing your contrast maths.

Luminance by channel
Red3%
Green82%
Blue14%

Green carries most of what the eye calls brightness — that is why WCAG weights it 0.7152.

Every format

HEX#42abda
HEX (8-digit)#42abdaff
RGBrgb(66, 171, 218)
RGBArgba(66, 171, 218, 1)
HSLhsl(199, 67%, 56%)
HSV / HSBhsv(199, 70%, 85%)
HWBhwb(199 26% 15%)
CMYKcmyk(70%, 22%, 0%, 15%)
LABlab(66.0 -15.1 -32.5)
LCHlch(66.0 35.9 245.0)
OKLCHoklch(0.701 0.117 231.3)
XYZ (D65)xyz(29.46, 35.34, 71.59)
Decimal4369370
Display P3color(display-p3 0.259 0.671 0.855)
Web-safe#3399CC

Copy-ready code

every platformclick to select
/* CSS */
color: #42abda;
background-color: #42abda;
/* CSS custom property */
--brand: #42abda;
/* Tailwind (arbitrary) */
class="text-[#42abda] bg-[#42abda]"
/* SCSS */
$brand: #42abda;
/* SwiftUI */
Color(red: 0.259, green: 0.671, blue: 0.855)
/* UIKit */
UIColor(red: 0.259, green: 0.671, blue: 0.855, alpha: 1)
/* Android XML */
<color name="brand">#42ABDA</color>
/* Android Compose */
Color(0xFF42ABDA)
/* Flutter */
Color(0xFF42ABDA)
/* Python / OpenCV (BGR) */
(218, 171, 66)
/* Python / PIL (RGB) */
(66, 171, 218)
/* Java AWT */
new Color(66, 171, 218)
/* .NET */
Color.FromArgb(255, 66, 171, 218)
/* OpenGL / Unity (0–1) */
(0.2588f, 0.6706f, 0.8549f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{66,171,218}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #42abda 85%, white);
border-color: color-mix(in oklab, #42abda 40%, transparent);
/* theme-aware in one line */
color: light-dark(#15506B, #D3E6EE);
/* relative colour syntax */
--hover: hsl(from #42abda h s calc(l - 7));

Design tokens

The same ramp in the four formats a team actually needs. Paste one and the whole palette lands with it.

css custom propertiesclick to select
:root {
  --brand-50: #F3F9FB;
  --brand-100: #E8F3F8;
  --brand-200: #CAE5F1;
  --brand-300: #A1D5ED;
  --brand-400: #72C0E3;
  --brand-500: #42abda;
  --brand-600: #289ACD;
  --brand-700: #2180AB;
  --brand-800: #1B6689;
  --brand-900: #174C63;
  --brand-950: #0F2F3E;
  --brand: #42abda;
  --brand-ink: #000000;
  --brand-surface: #F4F9FA;
  --brand-border: #C0DFED;
  --brand-hover: #299CD0;
  --brand-pressed: #2386B2;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141F24;
    --brand-ink: #D3E6EE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F3F9FB',
        100: '#E8F3F8',
        200: '#CAE5F1',
        300: '#A1D5ED',
        400: '#72C0E3',
        500: '#42abda',
        600: '#289ACD',
        700: '#2180AB',
        800: '#1B6689',
        900: '#174C63',
        950: '#0F2F3E',
        DEFAULT: '#42abda',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F3F9FB,
  '100': #E8F3F8,
  '200': #CAE5F1,
  '300': #A1D5ED,
  '400': #72C0E3,
  '500': #42abda,
  '600': #289ACD,
  '700': #2180AB,
  '800': #1B6689,
  '900': #174C63,
  '950': #0F2F3E,
);
$brand-base: #42abda;
$brand-ink: #000000;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F3F9FB", "$type": "color" },
      "100": { "$value": "#E8F3F8", "$type": "color" },
      "200": { "$value": "#CAE5F1", "$type": "color" },
      "300": { "$value": "#A1D5ED", "$type": "color" },
      "400": { "$value": "#72C0E3", "$type": "color" },
      "500": { "$value": "#42abda", "$type": "color" },
      "600": { "$value": "#289ACD", "$type": "color" },
      "700": { "$value": "#2180AB", "$type": "color" },
      "800": { "$value": "#1B6689", "$type": "color" },
      "900": { "$value": "#174C63", "$type": "color" },
      "950": { "$value": "#0F2F3E", "$type": "color" }
    },
    "brandInk": { "$value": "#000000", "$type": "color" }
  }
}

Best text color

Only one of black and white can be right. This is the one, with the number that proves it.

Readable at a glance#000000 on #42abda · 8.07:1
Use #000000AAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 2.60:1
AA fail · AA large fail · AAA fail
Aa
Black text · 8.07:1 · recommended
AA pass · AA large pass · AAA pass
Reading the other direction: #42abda as text scores 2.60:1 on white and 8.07:1 on black.
Best tinted ink on it, if plain black or white feels flat: #15506B at 3.37:1.

Make it accessible

A contrast checker tells you that you failed. This tells you what to ship instead — same hue, same saturation, lightness moved only as far as WCAG demands.

The quick fox
#207CA5 · 4.68:1
AA on white−17% L
#207CA5
The quick fox
#195F7F · 7.04:1
AAA on white−26% L
#195F7F
The quick fox
#42abda · 8.07:1
AA on blackalready passes
#42abda
The quick fox
#42abda · 8.07:1
AAA on blackalready passes
#42abda

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #299FD4 is enough for headings on white. Non-text elements such as icons, chart strokes and focus rings also sit at 3:1 under WCAG 2.2 (1.4.11).

Accessibility — WCAG contrast

Aa
#42abda on white: 2.60:1
AA ✗ fail · AA-large · AAA
Aa
#42abda on black: 8.07:1
AA ✓ pass · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #42abda as text on that neutral, and that neutral as text on #42abda.

NeutralRatioBoth directions
White2.60:1AaAa
Slate 502.49:1AaAa
Slate 1002.38:1AaAa
Slate 2002.11:1AaAa
Slate 3001.75:1AaAa
Slate 4001.01:1AaAa
Slate 5001.83:1AaAa
Slate 6002.91:1AaAa
Slate 7003.98:1AaAa
Slate 8005.62:1AaAa
Slate 9006.86:1AaAa
Black8.07:1AaAa
Colour vision deficiency
true color
protanopia · #93A9DC
deuteranopia · #7F9AD9
tritanopia · #00B8BB

Roughly one man in twelve has some form of colour vision deficiency. If any of the three panels above is hard to tell apart from a neighbouring colour in your palette, add a shape, an icon or a label so the meaning does not rest on hue alone.

Color scale — 50 to 950

A Tailwind-shaped ramp built around this exact hex. #42abda is pinned to step 500; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F3F9FB
#E8F3F8
#CAE5F1
#A1D5ED
#72C0E3
#42abda
#289ACD
#2180AB
#1B6689
#174C63
#0F2F3E
Base = 500Lightest = 50 · #F3F9FBDarkest = 950 · #0F2F3EText step on white = 800
Perceptual ramp — OKLCH

The same eleven steps expressed in OKLCH, where equal lightness numbers actually look equally spaced. HSL ramps go muddy in the yellows and washed out in the blues; this one does not. Modern browsers render it natively — the hex ramp above is the fallback.

50100200300400500600700800900950
oklch tokensclick to select
:root {
  --brand-50: oklch(0.97 0.029 231.3);
  --brand-100: oklch(0.94 0.047 231.3);
  --brand-200: oklch(0.88 0.070 231.3);
  --brand-300: oklch(0.80 0.091 231.3);
  --brand-400: oklch(0.72 0.108 231.3);
  --brand-500: oklch(0.64 0.117 231.3);
  --brand-600: oklch(0.56 0.117 231.3);
  --brand-700: oklch(0.48 0.110 231.3);
  --brand-800: oklch(0.40 0.098 231.3);
  --brand-900: oklch(0.32 0.082 231.3);
  --brand-950: oklch(0.24 0.064 231.3);
}

Colors that work with #42abda

Not a palette — a role sheet. Each swatch answers one question you will hit while building the component.

Text on it#000000
Black wins here
Surface#F4F9FA
Tinted page background
Border#C0DFED
Hairlines and dividers
Muted text#4B829B
Captions on the surface
Accent#DF473D
Second voice, not a rival
Dark variant#15506B
Hover, pressed, headers
Light variant#EAF6FB
Selected rows, tints
Dark surface#141F24
Dark-mode background
Hover#299CD0
One step down in lightness
Pressed#2386B2
Two steps down
Disabled#BACBD3
Chroma pulled out
Focus ring#49B6E8
Offset from the fill so it reads
Light mode
Everything in its place

Surface, border, heading and body all derive from this one hue, so the screen stays coherent without a second palette.

Primary actionSecondaryBadge
Dark mode
Same hue, inverted

Lightness flips, hue holds. The accent stays the anchor in both themes.

Primary actionSecondaryAccent

In real components

The same eight roles, wired into the interface patterns you will actually build with them. Every state below is a computed value, not a mock-up.

Buttons and states
Save changesHoverPressedDisabled
OutlineSubtleLinkFocused
Form field
you@company.com

Focus ring uses the light variant so the field still reads as one shape.

Send me product updates
Notice
Your export is ready

The file stays available for seven days. Download it before it expires.

NewBetaDraft
Data
Storage used68%
Acme LtdActive
NorthwindTrial
GlobexActive

How to use #42abda

Derived from its contrast, chroma and lightness — not from taste.

Works well for
  • Text and icons on dark surfaces
  • Primary buttons and calls to action
  • Focus rings, active and selected states
  • Brand accents, badges and data highlights
  • Chart series and data categories
Use with care
  • Text of any size on white — fails WCAG AA
  • Full-page backgrounds — tiring over long sessions
  • Thin strokes and 1px borders — they disappear on light UI
  • Pairing with a same-lightness hue — edges vibrate
Minimum size as text on white
Not as text
Safe as a fill behind white type
No — use #15506B
Safe as a 1px border on white
No — use #299FD4

Meaning and mood

What a colour in this family tends to signal, and how this particular chroma and lightness change the reading.

cleantechnicalfreshclinical

Cyan reads as water, air and infrastructure: cool, hygienic, engineered.

This is a confident chroma: strong enough to lead a brand, restrained enough to live in an interface all day. The mid lightness keeps it versatile in both themes.

Worth knowing

At high lightness it disappears into white surfaces and thin strokes vanish entirely.

Reads as
  • FormalityMedium
  • EnergyMedium-high
  • Weight44/100
  • TemperatureCool
  • ApproachabilityReserved

Colour associations are cultural and vary by market. Treat these as a starting point for a conversation with your audience, not a finding about them.

Similar colors

One move away from this hex in each direction. Every swatch is its own page.

Color relationships

The wheel positions with their names attached, so you can grab the one you actually need.

Complementary#DA7142
Analogous left#42DABD
Analogous right#425FDA
Split-complement 1#DA425F
Split-complement 2#DABD42
Triadic 1#DA42AB
Triadic 2#ABDA42
Tetradic#BD42DA
On the wheel
Base+30°−30°+120°+240°+180°199°

#42abda sits at 199°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red25.9%
Green67.1%
Blue85.5%
R · 0–255
66
0x42
G · 0–255
171
0xab
B · 0–255
218
0xda

CMYK percentages

Cyan69.7%
Magenta21.6%
Yellow0.0%
Key (black)14.5%

Total ink coverage is 106%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#42abda text on a black background

contrast 8.07:1

Card sample

#42abda text on a white background

contrast 2.60:1

Card sample

#42abda on grey

2.38:1

#42abda on its own surface

2.45:1

#42abda on its dark surface

6.45:1

CSS3 live lab

Text font color

The quick brown fox

color: #42abda;
Background color
Panel with #42abda background
background-color: #42abda;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #42abda;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(66, 171, 218, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(66, 171, 218, 0.45);
Border & gradient
Gradient panel
border: 3px solid #42abda;
background: linear-gradient(135deg, #42abda, #4246DA);
Gradient text

Gradient headline

background: linear-gradient(90deg, #42abda, #6442DA);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #42abda;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #42abda;
caret-color: #42abda;
Left rule
Pull quote or callout
border-left: 4px solid #42abda;
Ring + tint
Selected chip
background: #EAF6FB;
box-shadow: inset 0 0 0 2px #42abda;
Conic badge
68%
background: conic-gradient(#42abda 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #42abda over white; the bottom row is the same alpha over a checkerboard, so you can see what survives on a photo or a video.

Bottom row of hexes is the flattened result over white — use those when a design tool refuses transparency, or when you need a solid fallback.

alpha in every syntaxclick to select
rgba(66, 171, 218, 0.5)
rgb(66 171 218 / 50%)
#42abda80
hsl(199 67% 56% / 50%)
color-mix(in srgb, #42abda 50%, transparent)
Alpha8-digit hexFlat on white
10%#42abda1a#ECF7FB
20%#42abda33#D9EEF8
40%#42abda66#B3DDF0
60%#42abda99#8ECDE9
80%#42abdacc#68BCE1

Gradients from #42abda

Six recipes, each built from this hex and shown with the exact CSS that produced it.

Elevation
Same hue, three lightnesses — safe anywhere
background: linear-gradient(135deg, #75C2E4, #42abda 45%, #15506B);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #42abda, #3429D4);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #42abda, #DA7142);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #8FCDE9 0%, #42abda 45%, #15506B 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F4F9FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #6DE2C2 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #5C6ADF 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #15506B 0%, transparent 65%), #42abda;

Monochromatic scale

Palettes built from #42abda

Shades — darker

Tints — lighter

Tones — desaturated

Color harmonies

Nearest named colors

Ranked with CIEDE2000 across all 139 CSS keywords. Under ΔE 2 the eye stops telling them apart; over ΔE 10 they are plainly different colors.

#42abda in the real world

Where a color in this family tends to land, and the interface roles it is usually asked to play.

Industries
TechnologyTravelHealthcareMedia
Common UI roles
ButtonsLinksFocus statesCharts
Print note

Converts to four-color process without much drama. Proof it anyway.

On screens

Holds up across typical panel gamma. Still worth checking on an uncalibrated laptop, where mid-tones shift most.

In dark mode

Usable as-is on a dark surface at 8.07:1.

Explore nearby colors

Small, deliberate steps away from this hex — useful when you are hunting for the version of a colour that finally feels right.

#42abda, answered

What color is #42abda?

#42abda is a balanced vivid cyan, closest to Deep Sky Blue (ΔE2000 6.2). It sits at 199° on the hue wheel with 67% saturation and 56% lightness, which reads as cool.

What is the RGB value of #42abda?

rgb(66, 171, 218) — 66 red, 171 green and 218 blue out of 255, or 25.9% / 67.1% / 85.5% by channel.

What is #42abda in HSL and HSV?

hsl(199, 67%, 56%) and hsv(199, 70%, 85%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #42abda a light or a dark color?

It is a mid-tone. Relative luminance is 0.3535 and perceived brightness is 61%, so black text on it reaches 8.07:1.

Should I use black or white text on #42abda?

Black. It scores 8.07:1 against #42abda, versus 2.60:1 for white — AAA at any size.

Is #42abda accessible on a white background?

#42abda on white scores 2.60:1, which fails WCAG AA at every size. Darken it to #207CA5 to reach 4.5:1, or #195F7F for 7:1.

What is the complementary color of #42abda?

#DA7142 sits directly opposite on the wheel. Softer options are the split-complements #DA425F and #DABD42, which give the same contrast with far less vibration.

What colors go well with #42abda?

For interface work: #F4F9FA as the surface, #C0DFED for borders, #4B829B for secondary text, #DF473D as an accent and #15506B for hover and pressed states. For a palette, the analogous pair #42DABD and #425FDA stays calm, while #DA7142 is the loudest partner.

What is #42abda in CMYK for printing?

cmyk(70%, 22%, 0%, 15%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #42abda warm or cool?

Cool — it scores 95 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #42DAD1; nudged cooler, #4099DC.

Which Tailwind color is closest to #42abda?

The sky family — its 500 step is #0ea5e9, ΔE2000 4.5 away. That is a visible difference, so define #42abda as a custom token rather than reaching for the built-in.

How do I use #42abda in Tailwind CSS?

Inline it as an arbitrary value with bg-[#42abda] or text-[#42abda], or register the whole ramp under theme.extend.colors.brand so you get bg-brand-500 and friends. The generated 50–950 scale on this page is ready to paste into your config.

What is #42abda with 50% opacity?

rgba(66, 171, 218, 0.5), or #42abda80 in eight-digit hex. Over white that composites to #A1D5ED; over black, #21566D.

Is #42abda a web-safe color?

No. The nearest web-safe colour is #3399CC, ΔE2000 5.7 away. The palette only matters for legacy displays and some email clients now.

What does the color #42abda mean?

As a cyan, it reads clean, technical, fresh. Cyan reads as water, air and infrastructure: cool, hygienic, engineered. At this chroma the effect is amplified — it will dominate whatever sits beside it.

What gradient works with #42abda?

The safest is same-hue elevation: linear-gradient(135deg, #75C2E4, #42abda 45%, #15506B). For more colour, a short hue run to #3429D4 keeps it rich without turning muddy.

Work with #42abda in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #42abda at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.