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blue · cool

#39acf0

a balanced, electric blue · cool · closest name: Deep Sky Blue

Token name suggestion: True Harbour

RGB
57, 172, 240
HSL
202°, 86%, 58%
CMYK
76, 28, 0, 6
Luminance
0.3667

#39acf0 is a balanced electric blue, 202° on the wheel and 97/100 on the cool side. Put black text on it (8.33:1). As text it scores 2.52:1 on white — use #0E7ABA instead. Nearest name is Deep Sky Blue, nearest Tailwind family is sky.

hsl(202 86% 58%)rgb(57 172 240)Base step 500AAA inkCool

At a glance

Every number on this page in one read: what #39acf0 is made of, how bright it looks, and which way it leans.

Hex
#39acf0
Hue
202°
blue
Saturation
86%
electric
Lightness
58%
balanced
Brightness
94%
HSV value
Perceived
62%
weighted brightness
Luminance
0.3667
WCAG relative
Temperature
Cool
97/100 cool
Color family
Blue
Tone
Electric
Best ink
Black
8.33:1
Closest name
Deep Sky Blue
ΔE2000 6.3
Chroma
44.0
LCH, 0–130ish
OKLCH L
0.711
perceptual lightness
Tailwind
sky
500 · ΔE 2.6
Web-safe
#3399FF
nearest of 216
Where it sits
Hue202° of 360°
Saturation86%
Lightness58%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #39acf0.

Temperature
Warm ← → Cool97% 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
Red2%
Green80%
Blue17%

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

Every format

HEX#39acf0
HEX (8-digit)#39acf0ff
RGBrgb(57, 172, 240)
RGBArgba(57, 172, 240, 1)
HSLhsl(202, 86%, 58%)
HSV / HSBhsv(202, 76%, 94%)
HWBhwb(202 22% 6%)
CMYKcmyk(76%, 28%, 0%, 6%)
LABlab(67.0 -9.4 -43.0)
LCHlch(67.0 44.0 257.6)
OKLCHoklch(0.711 0.141 239.7)
XYZ (D65)xyz(32.16, 36.66, 87.80)
Decimal3779824
Display P3color(display-p3 0.224 0.675 0.941)
Web-safe#3399FF

Copy-ready code

every platformclick to select
/* CSS */
color: #39acf0;
background-color: #39acf0;
/* CSS custom property */
--brand: #39acf0;
/* Tailwind (arbitrary) */
class="text-[#39acf0] bg-[#39acf0]"
/* SCSS */
$brand: #39acf0;
/* SwiftUI */
Color(red: 0.224, green: 0.675, blue: 0.941)
/* UIKit */
UIColor(red: 0.224, green: 0.675, blue: 0.941, alpha: 1)
/* Android XML */
<color name="brand">#39ACF0</color>
/* Android Compose */
Color(0xFF39ACF0)
/* Flutter */
Color(0xFF39ACF0)
/* Python / OpenCV (BGR) */
(240, 172, 57)
/* Python / PIL (RGB) */
(57, 172, 240)
/* Java AWT */
new Color(57, 172, 240)
/* .NET */
Color.FromArgb(255, 57, 172, 240)
/* OpenGL / Unity (0–1) */
(0.2235f, 0.6745f, 0.9412f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{57,172,240}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #39acf0 85%, white);
border-color: color-mix(in oklab, #39acf0 40%, transparent);
/* theme-aware in one line */
color: light-dark(#094E77, #D3E4EE);
/* relative colour syntax */
--hover: hsl(from #39acf0 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: #F2F9FD;
  --brand-100: #E5F2FA;
  --brand-200: #C5E4F7;
  --brand-300: #97D3F7;
  --brand-400: #63BDF3;
  --brand-500: #39acf0;
  --brand-600: #1195E4;
  --brand-700: #0E7CBE;
  --brand-800: #0C6498;
  --brand-900: #0D4A6E;
  --brand-950: #082E44;
  --brand: #39acf0;
  --brand-ink: #000000;
  --brand-surface: #F4F8FA;
  --brand-border: #C0DCED;
  --brand-hover: #189EED;
  --brand-pressed: #108AD2;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141E24;
    --brand-ink: #D3E4EE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F2F9FD',
        100: '#E5F2FA',
        200: '#C5E4F7',
        300: '#97D3F7',
        400: '#63BDF3',
        500: '#39acf0',
        600: '#1195E4',
        700: '#0E7CBE',
        800: '#0C6498',
        900: '#0D4A6E',
        950: '#082E44',
        DEFAULT: '#39acf0',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F2F9FD,
  '100': #E5F2FA,
  '200': #C5E4F7,
  '300': #97D3F7,
  '400': #63BDF3,
  '500': #39acf0,
  '600': #1195E4,
  '700': #0E7CBE,
  '800': #0C6498,
  '900': #0D4A6E,
  '950': #082E44,
);
$brand-base: #39acf0;
$brand-ink: #000000;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F2F9FD", "$type": "color" },
      "100": { "$value": "#E5F2FA", "$type": "color" },
      "200": { "$value": "#C5E4F7", "$type": "color" },
      "300": { "$value": "#97D3F7", "$type": "color" },
      "400": { "$value": "#63BDF3", "$type": "color" },
      "500": { "$value": "#39acf0", "$type": "color" },
      "600": { "$value": "#1195E4", "$type": "color" },
      "700": { "$value": "#0E7CBE", "$type": "color" },
      "800": { "$value": "#0C6498", "$type": "color" },
      "900": { "$value": "#0D4A6E", "$type": "color" },
      "950": { "$value": "#082E44", "$type": "color" }
    },
    "brandInk": { "$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 #39acf0 · 8.33:1
Use #000000AAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 2.52:1
AA fail · AA large fail · AAA fail
Aa
Black text · 8.33:1 · recommended
AA pass · AA large pass · AAA pass
Reading the other direction: #39acf0 as text scores 2.52:1 on white and 8.33:1 on black.
Best tinted ink on it, if plain black or white feels flat: #094E77 at 3.52:1.

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
#0E7ABA · 4.65:1
AA on white−19% L
#0E7ABA
The quick fox
#0A5B8A · 7.30:1
AAA on white−29% L
#0A5B8A
The quick fox
#39acf0 · 8.33:1
AA on blackalready passes
#39acf0
The quick fox
#39acf0 · 8.33:1
AAA on blackalready passes
#39acf0

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #139CED 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
#39acf0 on white: 2.52:1
AA ✗ fail · AA-large · AAA
Aa
#39acf0 on black: 8.33:1
AA ✓ pass · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #39acf0 as text on that neutral, and that neutral as text on #39acf0.

NeutralRatioBoth directions
White2.52:1AaAa
Slate 502.41:1AaAa
Slate 1002.30:1AaAa
Slate 2002.04:1AaAa
Slate 3001.70:1AaAa
Slate 4001.02:1AaAa
Slate 5001.89:1AaAa
Slate 6003.01:1AaAa
Slate 7004.11:1AaAa
Slate 8005.80:1AaAa
Slate 9007.08:1AaAa
Black8.33:1AaAa
Colour vision deficiency
true color
protanopia · #8CADF3
deuteranopia · #739CEF
tritanopia · #00BDC4

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. #39acf0 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.

#F2F9FD
#E5F2FA
#C5E4F7
#97D3F7
#63BDF3
#39acf0
#1195E4
#0E7CBE
#0C6498
#0D4A6E
#082E44
Base = 500Lightest = 50 · #F2F9FDDarkest = 950 · #082E44Text step on white = 700
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 0.035 239.7);
  --brand-100: oklch(0.94 0.056 239.7);
  --brand-200: oklch(0.88 0.085 239.7);
  --brand-300: oklch(0.80 0.110 239.7);
  --brand-400: oklch(0.72 0.130 239.7);
  --brand-500: oklch(0.64 0.141 239.7);
  --brand-600: oklch(0.56 0.141 239.7);
  --brand-700: oklch(0.48 0.133 239.7);
  --brand-800: oklch(0.40 0.118 239.7);
  --brand-900: oklch(0.32 0.099 239.7);
  --brand-950: oklch(0.24 0.078 239.7);
}

Colors that work with #39acf0

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#F4F8FA
Tinted page background
Border#C0DCED
Hairlines and dividers
Muted text#4B7D9B
Captions on the surface
Accent#F44C35
Second voice, not a rival
Dark variant#094E77
Hover, pressed, headers
Light variant#E7F5FD
Selected rows, tints
Dark surface#141E24
Dark-mode background
Hover#189EED
One step down in lightness
Pressed#108AD2
Two steps down
Disabled#C1CFD8
Chroma pulled out
Focus ring#42B6FB
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 #39acf0

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
  • 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 #094E77
Safe as a 1px border on white
No — use #139CED

Meaning and mood

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

trustedcalmcompetentcorporate

The default of institutions for a reason: blue is read as stable and safe across nearly every culture that has been surveyed.

At this chroma the association is amplified — it will dominate anything placed beside it, so give it space and use it sparingly. The mid lightness keeps it versatile in both themes.

Worth knowing

It is also the most crowded hue on the web. Distinctiveness has to come from your other choices.

Reads as
  • FormalityLow
  • EnergyHigh
  • Weight42/100
  • 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#F07D39
Analogous left#39F0D8
Analogous right#3950F0
Split-complement 1#F03950
Split-complement 2#F0D839
Triadic 1#F039AC
Triadic 2#ACF039
Tetradic#D839F0
On the wheel
Base+30°−30°+120°+240°+180°202°

#39acf0 sits at 202°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red22.4%
Green67.5%
Blue94.1%
R · 0–255
57
0x39
G · 0–255
172
0xac
B · 0–255
240
0xf0

CMYK percentages

Cyan76.3%
Magenta28.3%
Yellow0.0%
Key (black)5.9%

Total ink coverage is 111%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#39acf0 text on a black background

contrast 8.33:1

Card sample

#39acf0 text on a white background

contrast 2.52:1

Card sample

#39acf0 on grey

2.30:1

#39acf0 on its own surface

2.36:1

#39acf0 on its dark surface

6.72:1

CSS3 live lab

Text font color

The quick brown fox

color: #39acf0;
Background color
Panel with #39acf0 background
background-color: #39acf0;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #39acf0;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(57, 172, 240, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(57, 172, 240, 0.45);
Border & gradient
Gradient panel
border: 3px solid #39acf0;
background: linear-gradient(135deg, #39acf0, #4039F0);
Gradient text

Gradient headline

background: linear-gradient(90deg, #39acf0, #6E39F0);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #39acf0;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #39acf0;
caret-color: #39acf0;
Left rule
Pull quote or callout
border-left: 4px solid #39acf0;
Ring + tint
Selected chip
background: #E7F5FD;
box-shadow: inset 0 0 0 2px #39acf0;
Conic badge
68%
background: conic-gradient(#39acf0 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #39acf0 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(57, 172, 240, 0.5)
rgb(57 172 240 / 50%)
#39acf080
hsl(202 86% 58% / 50%)
color-mix(in srgb, #39acf0 50%, transparent)
Alpha8-digit hexFlat on white
10%#39acf01a#EBF7FE
20%#39acf033#D7EEFC
40%#39acf066#B0DEF9
60%#39acf099#88CDF6
80%#39acf0cc#61BDF3

Gradients from #39acf0

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, #72C4F4, #39acf0 45%, #094E77);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #39acf0, #361CEE);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #39acf0, #F07D39);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #8ED0F6 0%, #39acf0 45%, #094E77 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F4F8FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #68F4D6 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #555CF2 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #094E77 0%, transparent 65%), #39acf0;

Monochromatic scale

Palettes built from #39acf0

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.

#39acf0 in the real world

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

Industries
TechnologyFinanceHealthcareEnterprise SaaS
Common UI roles
ButtonsLinksFocus statesCharts
Print note

Sits outside most CMYK gamuts — expect a duller press result, or specify a spot ink.

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 8.33:1.

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.

#39acf0, answered

What color is #39acf0?

#39acf0 is a balanced electric blue, closest to Deep Sky Blue (ΔE2000 6.3). It sits at 202° on the hue wheel with 86% saturation and 58% lightness, which reads as cool.

What is the RGB value of #39acf0?

rgb(57, 172, 240) — 57 red, 172 green and 240 blue out of 255, or 22.4% / 67.5% / 94.1% by channel.

What is #39acf0 in HSL and HSV?

hsl(202, 86%, 58%) and hsv(202, 76%, 94%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #39acf0 a light or a dark color?

It is a mid-tone. Relative luminance is 0.3667 and perceived brightness is 62%, so black text on it reaches 8.33:1.

Should I use black or white text on #39acf0?

Black. It scores 8.33:1 against #39acf0, versus 2.52:1 for white — AAA at any size.

Is #39acf0 accessible on a white background?

#39acf0 on white scores 2.52:1, which fails WCAG AA at every size. Darken it to #0E7ABA to reach 4.5:1, or #0A5B8A for 7:1.

What is the complementary color of #39acf0?

#F07D39 sits directly opposite on the wheel. Softer options are the split-complements #F03950 and #F0D839, which give the same contrast with far less vibration.

What colors go well with #39acf0?

For interface work: #F4F8FA as the surface, #C0DCED for borders, #4B7D9B for secondary text, #F44C35 as an accent and #094E77 for hover and pressed states. For a palette, the analogous pair #39F0D8 and #3950F0 stays calm, while #F07D39 is the loudest partner.

What is #39acf0 in CMYK for printing?

cmyk(76%, 28%, 0%, 6%). This is a screen-to-ink approximation — a color this saturated sits outside most CMYK gamuts and will print duller than it looks here.

Is #39acf0 warm or cool?

Cool — it scores 97 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #39EFF0; nudged cooler, #1F92F1.

Which Tailwind color is closest to #39acf0?

The sky family — its 500 step is #0ea5e9, ΔE2000 2.6 away. That is close enough to swap in without anyone noticing.

How do I use #39acf0 in Tailwind CSS?

Inline it as an arbitrary value with bg-[#39acf0] or text-[#39acf0], 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 #39acf0 with 50% opacity?

rgba(57, 172, 240, 0.5), or #39acf080 in eight-digit hex. Over white that composites to #9CD6F8; over black, #1D5678.

Is #39acf0 a web-safe color?

No. The nearest web-safe colour is #3399FF, ΔE2000 7.9 away. The palette only matters for legacy displays and some email clients now.

What does the color #39acf0 mean?

As a blue, it reads trusted, calm, competent. The default of institutions for a reason: blue is read as stable and safe across nearly every culture that has been surveyed. At this chroma the effect is amplified — it will dominate whatever sits beside it.

What gradient works with #39acf0?

The safest is same-hue elevation: linear-gradient(135deg, #72C4F4, #39acf0 45%, #094E77). For more colour, a short hue run to #361CEE keeps it rich without turning muddy.

Work with #39acf0 in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #39acf0 at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.