Skip to content
blue · cool

#2579af

a dark, vivid blue · cool · closest name: Steel Blue

Token name suggestion: Slate Cobalt

RGB
37, 121, 175
HSL
204°, 65%, 42%
CMYK
79, 31, 0, 31
Luminance
0.1716

#2579af is a dark vivid blue, 204° on the wheel and 97/100 on the cool side. Put white text on it (4.74:1). As text it scores 4.74:1 on white — safe at any size. Nearest name is Steel Blue, nearest Tailwind family is blue.

hsl(204 65% 42%)rgb(37 121 175)Base step 700AA inkCool

At a glance

Every number on this page in one read: what #2579af is made of, how bright it looks, and which way it leans.

Hex
#2579af
Hue
204°
blue
Saturation
65%
vivid
Lightness
42%
dark
Brightness
69%
HSV value
Perceived
44%
weighted brightness
Luminance
0.1716
WCAG relative
Temperature
Cool
97/100 cool
Color family
Blue
Tone
Vivid
Best ink
White
4.74:1
Closest name
Steel Blue
ΔE2000 4.5
Chroma
36.1
LCH, 0–130ish
OKLCH L
0.553
perceptual lightness
Tailwind
blue
500 · ΔE 10.4
Web-safe
#336699
nearest of 216
Where it sits
Hue204° of 360°
Saturation65%
Lightness42%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #2579af.

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%
Blue18%

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

Every format

HEX#2579af
HEX (8-digit)#2579afff
RGBrgb(37, 121, 175)
RGBArgba(37, 121, 175, 1)
HSLhsl(204, 65%, 42%)
HSV / HSBhsv(203, 79%, 69%)
HWBhwb(204 15% 31%)
CMYKcmyk(79%, 31%, 0%, 31%)
LABlab(48.5 -5.7 -35.6)
LCHlch(48.5 36.1 261.0)
OKLCHoklch(0.553 0.115 242.0)
XYZ (D65)xyz(15.34, 17.16, 43.05)
Decimal2455983
Display P3color(display-p3 0.145 0.475 0.686)
Web-safe#336699

Copy-ready code

every platformclick to select
/* CSS */
color: #2579af;
background-color: #2579af;
/* CSS custom property */
--brand: #2579af;
/* Tailwind (arbitrary) */
class="text-[#2579af] bg-[#2579af]"
/* SCSS */
$brand: #2579af;
/* SwiftUI */
Color(red: 0.145, green: 0.475, blue: 0.686)
/* UIKit */
UIColor(red: 0.145, green: 0.475, blue: 0.686, alpha: 1)
/* Android XML */
<color name="brand">#2579AF</color>
/* Android Compose */
Color(0xFF2579AF)
/* Flutter */
Color(0xFF2579AF)
/* Python / OpenCV (BGR) */
(175, 121, 37)
/* Python / PIL (RGB) */
(37, 121, 175)
/* Java AWT */
new Color(37, 121, 175)
/* .NET */
Color.FromArgb(255, 37, 121, 175)
/* OpenGL / Unity (0–1) */
(0.1451f, 0.4745f, 0.6863f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{37,121,175}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #2579af 85%, white);
border-color: color-mix(in oklab, #2579af 40%, transparent);
/* theme-aware in one line */
color: light-dark(#164969, #D3E3EE);
/* relative colour syntax */
--hover: hsl(from #2579af 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: #F3F8FB;
  --brand-100: #E8F1F7;
  --brand-200: #CBE2F1;
  --brand-300: #A2CFEB;
  --brand-400: #74B7E2;
  --brand-500: #469FD8;
  --brand-600: #2B8CCA;
  --brand-700: #2579af;
  --brand-800: #1C5D87;
  --brand-900: #194562;
  --brand-950: #0F2B3D;
  --brand: #2579af;
  --brand-ink: #ffffff;
  --brand-surface: #F4F8FA;
  --brand-border: #C0DBED;
  --brand-hover: #1F6592;
  --brand-pressed: #195074;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141E24;
    --brand-ink: #D3E3EE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F3F8FB',
        100: '#E8F1F7',
        200: '#CBE2F1',
        300: '#A2CFEB',
        400: '#74B7E2',
        500: '#469FD8',
        600: '#2B8CCA',
        700: '#2579af',
        800: '#1C5D87',
        900: '#194562',
        950: '#0F2B3D',
        DEFAULT: '#2579af',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F3F8FB,
  '100': #E8F1F7,
  '200': #CBE2F1,
  '300': #A2CFEB,
  '400': #74B7E2,
  '500': #469FD8,
  '600': #2B8CCA,
  '700': #2579af,
  '800': #1C5D87,
  '900': #194562,
  '950': #0F2B3D,
);
$brand-base: #2579af;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F3F8FB", "$type": "color" },
      "100": { "$value": "#E8F1F7", "$type": "color" },
      "200": { "$value": "#CBE2F1", "$type": "color" },
      "300": { "$value": "#A2CFEB", "$type": "color" },
      "400": { "$value": "#74B7E2", "$type": "color" },
      "500": { "$value": "#469FD8", "$type": "color" },
      "600": { "$value": "#2B8CCA", "$type": "color" },
      "700": { "$value": "#2579af", "$type": "color" },
      "800": { "$value": "#1C5D87", "$type": "color" },
      "900": { "$value": "#194562", "$type": "color" },
      "950": { "$value": "#0F2B3D", "$type": "color" }
    },
    "brandInk": { "$value": "#ffffff", "$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#ffffff on #2579af · 4.74:1
Use #ffffffAA at every size, AAA for large text only.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 4.74:1 · recommended
AA pass · AA large pass · AAA fail
Aa
Black text · 4.43:1
AA fail · AA large pass · AAA fail
Reading the other direction: #2579af as text scores 4.74:1 on white and 4.43:1 on black.
Best tinted ink on it, if plain black or white feels flat: #EAF4FB at 4.25:1.

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
#2579af · 4.74:1
AA on whitealready passes
#2579af
The quick fox
#1C5C85 · 7.19:1
AAA on white−10% L
#1C5C85
The quick fox
#267CB3 · 4.62:1
AA on black+1% L
#267CB3
The quick fox
#449ED7 · 7.12:1
AAA on black+14% L
#449ED7

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #2579AF 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
#2579af on white: 4.74:1
AA ✓ pass · AA-large · AAA
Aa
#2579af on black: 4.43:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #2579af as text on that neutral, and that neutral as text on #2579af.

NeutralRatioBoth directions
White4.74:1AaAa
Slate 504.53:1AaAa
Slate 1004.32:1AaAa
Slate 2003.84:1AaAa
Slate 3003.19:1AaAa
Slate 4001.85:1AaAa
Slate 5001.00:1AaAa
Slate 6001.60:1AaAa
Slate 7002.19:1AaAa
Slate 8003.09:1AaAa
Slate 9003.77:1AaAa
Black4.43:1AaAa
Colour vision deficiency
true color
protanopia · #607AB1
deuteranopia · #4D6DAE
tritanopia · #00868C

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. #2579af is pinned to step 700; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F3F8FB
#E8F1F7
#CBE2F1
#A2CFEB
#74B7E2
#469FD8
#2B8CCA
#2579af
#1C5D87
#194562
#0F2B3D
Base = 700Lightest = 50 · #F3F8FBDarkest = 950 · #0F2B3DText 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 0.029 242.0);
  --brand-100: oklch(0.94 0.046 242.0);
  --brand-200: oklch(0.88 0.069 242.0);
  --brand-300: oklch(0.80 0.089 242.0);
  --brand-400: oklch(0.72 0.105 242.0);
  --brand-500: oklch(0.64 0.115 242.0);
  --brand-600: oklch(0.56 0.115 242.0);
  --brand-700: oklch(0.48 0.108 242.0);
  --brand-800: oklch(0.40 0.096 242.0);
  --brand-900: oklch(0.32 0.080 242.0);
  --brand-950: oklch(0.24 0.063 242.0);
}

Colors that work with #2579af

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

Text on it#ffffff
White wins here
Surface#F4F8FA
Tinted page background
Border#C0DBED
Hairlines and dividers
Muted text#4B7B9B
Captions on the surface
Accent#B33621
Second voice, not a rival
Dark variant#164969
Hover, pressed, headers
Light variant#EAF4FB
Selected rows, tints
Dark surface#141E24
Dark-mode background
Hover#1F6592
One step down in lightness
Pressed#195074
Two steps down
Disabled#8EA7B7
Chroma pulled out
Focus ring#1D87CC
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 #2579af

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

Works well for
  • Body text and links on white
  • Primary buttons and calls to action
  • Focus rings, active and selected states
  • Headers, footers and dark-mode surfaces
  • Brand accents, badges and data highlights
Use with care
  • Full-page backgrounds — tiring over long sessions
  • Black text placed on it
  • Pairing with a same-lightness hue — edges vibrate
Minimum size as text on white
Any size
Safe as a fill behind white type
Yes
Safe as a 1px border on white
Yes

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.

This is a confident chroma: strong enough to lead a brand, restrained enough to live in an interface all day. The low lightness adds weight and formality.

Worth knowing

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

Reads as
  • FormalityHigh
  • EnergyMedium-high
  • Weight58/100
  • 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#AF5B25
Analogous left#25AFA0
Analogous right#2534AF
Split-complement 1#AF2534
Split-complement 2#AFA025
Triadic 1#AF2579
Triadic 2#79AF25
Tetradic#A025AF
On the wheel
Base+30°−30°+120°+240°+180°204°

#2579af sits at 204°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red14.5%
Green47.5%
Blue68.6%
R · 0–255
37
0x25
G · 0–255
121
0x79
B · 0–255
175
0xaf

CMYK percentages

Cyan78.9%
Magenta30.9%
Yellow0.0%
Key (black)31.4%

Total ink coverage is 141%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#2579af text on a black background

contrast 4.43:1

Card sample

#2579af text on a white background

contrast 4.74:1

Card sample

#2579af on grey

4.32:1

#2579af on its own surface

4.43:1

#2579af on its dark surface

3.57:1

CSS3 live lab

Text font color

The quick brown fox

color: #2579af;
Background color
Panel with #2579af background
background-color: #2579af;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #2579af;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(37, 121, 175, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(37, 121, 175, 0.45);
Border & gradient
Gradient panel
border: 3px solid #2579af;
background: linear-gradient(135deg, #2579af, #2D25AF);
Gradient text

Gradient headline

background: linear-gradient(90deg, #2579af, #5025AF);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #2579af;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #2579af;
caret-color: #2579af;
Left rule
Pull quote or callout
border-left: 4px solid #2579af;
Ring + tint
Selected chip
background: #EAF4FB;
box-shadow: inset 0 0 0 2px #2579af;
Conic badge
68%
background: conic-gradient(#2579af 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #2579af 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(37, 121, 175, 0.5)
rgb(37 121 175 / 50%)
#2579af80
hsl(204 65% 42% / 50%)
color-mix(in srgb, #2579af 50%, transparent)
Alpha8-digit hexFlat on white
10%#2579af1a#E9F2F7
20%#2579af33#D3E4EF
40%#2579af66#A8C9DF
60%#2579af99#7CAFCF
80%#2579afcc#5194BF

Gradients from #2579af

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, #3C99D6, #2579af 45%, #164969);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #2579af, #302096);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #2579af, #AF5B25);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #55A7DB 0%, #2579af 45%, #164969 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%, #33D4B5 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #2A2EC8 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #164969 0%, transparent 65%), #2579af;

Monochromatic scale

Palettes built from #2579af

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.

#2579af 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

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

Too dim on dark surfaces at 4.43:1 — lift it to #267CB3 for body text, or reserve it for fills.

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.

#2579af, answered

What color is #2579af?

#2579af is a dark vivid blue, closest to Steel Blue (ΔE2000 4.5). It sits at 204° on the hue wheel with 65% saturation and 42% lightness, which reads as cool.

What is the RGB value of #2579af?

rgb(37, 121, 175) — 37 red, 121 green and 175 blue out of 255, or 14.5% / 47.5% / 68.6% by channel.

What is #2579af in HSL and HSV?

hsl(204, 65%, 42%) and hsv(203, 79%, 69%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #2579af a light or a dark color?

It is a dark color. Relative luminance is 0.1716 and perceived brightness is 44%, so white text on it reaches 4.74:1.

Should I use black or white text on #2579af?

White. It scores 4.74:1 against #2579af, versus 4.43:1 for black — AA at any size.

Is #2579af accessible on a white background?

#2579af on white scores 4.74:1, which clears AA at every size but not AAA.

What is the complementary color of #2579af?

#AF5B25 sits directly opposite on the wheel. Softer options are the split-complements #AF2534 and #AFA025, which give the same contrast with far less vibration.

What colors go well with #2579af?

For interface work: #F4F8FA as the surface, #C0DBED for borders, #4B7B9B for secondary text, #B33621 as an accent and #164969 for hover and pressed states. For a palette, the analogous pair #25AFA0 and #2534AF stays calm, while #AF5B25 is the loudest partner.

What is #2579af in CMYK for printing?

cmyk(79%, 31%, 0%, 31%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #2579af 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 #25ACAF; nudged cooler, #1F619C.

Which Tailwind color is closest to #2579af?

The blue family — its 500 step is #3b82f6, ΔE2000 10.4 away. That is a visible difference, so define #2579af as a custom token rather than reaching for the built-in.

How do I use #2579af in Tailwind CSS?

Inline it as an arbitrary value with bg-[#2579af] or text-[#2579af], 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 #2579af with 50% opacity?

rgba(37, 121, 175, 0.5), or #2579af80 in eight-digit hex. Over white that composites to #92BCD7; over black, #133D58.

Is #2579af a web-safe color?

No. The nearest web-safe colour is #336699, ΔE2000 7.7 away. The palette only matters for legacy displays and some email clients now.

What does the color #2579af 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 #2579af?

The safest is same-hue elevation: linear-gradient(135deg, #3C99D6, #2579af 45%, #164969). For more colour, a short hue run to #302096 keeps it rich without turning muddy.

Work with #2579af in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #2579af at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.