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blue · cool

#283f4b

a deep, soft blue · cool · closest name: Dark Slate Gray

Token name suggestion: Ink Sapphire

RGB
40, 63, 75
HSL
201°, 30%, 23%
CMYK
47, 16, 0, 71
Luminance
0.0451

#283f4b is a deep soft blue, 201° on the wheel and 90/100 on the cool side. Put white text on it (11.04:1). As text it scores 11.04:1 on white — safe at any size. Nearest name is Dark Slate Gray, nearest Tailwind family is gray.

hsl(201 30% 23%)rgb(40 63 75)Base step 900AAA inkCool

At a glance

Every number on this page in one read: what #283f4b is made of, how bright it looks, and which way it leans.

Hex
#283f4b
Hue
201°
blue
Saturation
30%
soft
Lightness
23%
deep
Brightness
29%
HSV value
Perceived
23%
weighted brightness
Luminance
0.0451
WCAG relative
Temperature
Cool
90/100 cool
Color family
Blue
Tone
Soft
Best ink
White
11.04:1
Closest name
Dark Slate Gray
ΔE2000 9.7
Chroma
11.4
LCH, 0–130ish
OKLCH L
0.354
perceptual lightness
Tailwind
gray
500 · ΔE 20.2
Web-safe
#333333
nearest of 216
Where it sits
Hue201° of 360°
Saturation30%
Lightness23%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #283f4b.

Temperature
Warm ← → Cool90% 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
Red10%
Green79%
Blue11%

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

Every format

HEX#283f4b
HEX (8-digit)#283f4bff
RGBrgb(40, 63, 75)
RGBArgba(40, 63, 75, 1)
HSLhsl(201, 30%, 23%)
HSV / HSBhsv(201, 47%, 29%)
HWBhwb(201 16% 71%)
CMYKcmyk(47%, 16%, 0%, 71%)
LABlab(25.3 -5.3 -10.1)
LCHlch(25.3 11.4 242.6)
OKLCHoklch(0.354 0.035 231.8)
XYZ (D65)xyz(3.92, 4.51, 7.32)
Decimal2637643
Display P3color(display-p3 0.157 0.247 0.294)
Web-safe#333333

Copy-ready code

every platformclick to select
/* CSS */
color: #283f4b;
background-color: #283f4b;
/* CSS custom property */
--brand: #283f4b;
/* Tailwind (arbitrary) */
class="text-[#283f4b] bg-[#283f4b]"
/* SCSS */
$brand: #283f4b;
/* SwiftUI */
Color(red: 0.157, green: 0.247, blue: 0.294)
/* UIKit */
UIColor(red: 0.157, green: 0.247, blue: 0.294, alpha: 1)
/* Android XML */
<color name="brand">#283F4B</color>
/* Android Compose */
Color(0xFF283F4B)
/* Flutter */
Color(0xFF283F4B)
/* Python / OpenCV (BGR) */
(75, 63, 40)
/* Python / PIL (RGB) */
(40, 63, 75)
/* Java AWT */
new Color(40, 63, 75)
/* .NET */
Color.FromArgb(255, 40, 63, 75)
/* OpenGL / Unity (0–1) */
(0.1569f, 0.2471f, 0.2941f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{40,63,75}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #283f4b 85%, white);
border-color: color-mix(in oklab, #283f4b 40%, transparent);
/* theme-aware in one line */
color: light-dark(#2C4653, #D7E3EA);
/* relative colour syntax */
--hover: hsl(from #283f4b 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: #F6F8F9;
  --brand-100: #ECF1F3;
  --brand-200: #D5E1E7;
  --brand-300: #B6CCD8;
  --brand-400: #91B3C4;
  --brand-500: #6D99B1;
  --brand-600: #5586A0;
  --brand-700: #477085;
  --brand-800: #39596A;
  --brand-900: #283f4b;
  --brand-950: #1C2A31;
  --brand: #283f4b;
  --brand-ink: #ffffff;
  --brand-surface: #F5F8FA;
  --brand-border: #CADAE3;
  --brand-hover: #1C2B34;
  --brand-pressed: #0F181C;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141F24;
    --brand-ink: #D7E3EA;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F6F8F9',
        100: '#ECF1F3',
        200: '#D5E1E7',
        300: '#B6CCD8',
        400: '#91B3C4',
        500: '#6D99B1',
        600: '#5586A0',
        700: '#477085',
        800: '#39596A',
        900: '#283f4b',
        950: '#1C2A31',
        DEFAULT: '#283f4b',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F6F8F9,
  '100': #ECF1F3,
  '200': #D5E1E7,
  '300': #B6CCD8,
  '400': #91B3C4,
  '500': #6D99B1,
  '600': #5586A0,
  '700': #477085,
  '800': #39596A,
  '900': #283f4b,
  '950': #1C2A31,
);
$brand-base: #283f4b;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F6F8F9", "$type": "color" },
      "100": { "$value": "#ECF1F3", "$type": "color" },
      "200": { "$value": "#D5E1E7", "$type": "color" },
      "300": { "$value": "#B6CCD8", "$type": "color" },
      "400": { "$value": "#91B3C4", "$type": "color" },
      "500": { "$value": "#6D99B1", "$type": "color" },
      "600": { "$value": "#5586A0", "$type": "color" },
      "700": { "$value": "#477085", "$type": "color" },
      "800": { "$value": "#39596A", "$type": "color" },
      "900": { "$value": "#283f4b", "$type": "color" },
      "950": { "$value": "#1C2A31", "$type": "color" }
    },
    "brandInk": { "$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 #283f4b · 11.04:1
Use #ffffffAAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 11.04:1 · recommended
AA pass · AA large pass · AAA pass
Aa
Black text · 1.90:1
AA fail · AA large fail · AAA fail
Reading the other direction: #283f4b as text scores 11.04:1 on white and 1.90:1 on black.
Best tinted ink on it, if plain black or white feels flat: #EEF3F6 at 9.87:1.

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
#283f4b · 11.04:1
AA on whitealready passes
#283f4b
The quick fox
#283f4b · 11.04:1
AAA on whitealready passes
#283f4b
The quick fox
#4F7C94 · 4.64:1
AA on black+22% L
#4F7C94
The quick fox
#729DB4 · 7.20:1
AAA on black+35% L
#729DB4

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #283F4B 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
#283f4b on white: 11.04:1
AA ✓ pass · AA-large · AAA
Aa
#283f4b on black: 1.90:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #283f4b as text on that neutral, and that neutral as text on #283f4b.

NeutralRatioBoth directions
White11.04:1AaAa
Slate 5010.55:1AaAa
Slate 10010.07:1AaAa
Slate 2008.95:1AaAa
Slate 3007.43:1AaAa
Slate 4004.30:1AaAa
Slate 5002.32:1AaAa
Slate 6001.46:1AaAa
Slate 7001.07:1AaAa
Slate 8001.33:1AaAa
Slate 9001.62:1AaAa
Black1.90:1AaAa
Colour vision deficiency
true color
protanopia · #393E4C
deuteranopia · #343A4B
tritanopia · #1A4243

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. #283f4b is pinned to step 900; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F6F8F9
#ECF1F3
#D5E1E7
#B6CCD8
#91B3C4
#6D99B1
#5586A0
#477085
#39596A
#283f4b
#1C2A31
Base = 900Lightest = 50 · #F6F8F9Darkest = 950 · #1C2A31Text 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 0.009 231.8);
  --brand-100: oklch(0.94 0.014 231.8);
  --brand-200: oklch(0.88 0.021 231.8);
  --brand-300: oklch(0.80 0.028 231.8);
  --brand-400: oklch(0.72 0.033 231.8);
  --brand-500: oklch(0.64 0.035 231.8);
  --brand-600: oklch(0.56 0.035 231.8);
  --brand-700: oklch(0.48 0.033 231.8);
  --brand-800: oklch(0.40 0.030 231.8);
  --brand-900: oklch(0.32 0.025 231.8);
  --brand-950: oklch(0.24 0.020 231.8);
}

Colors that work with #283f4b

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#F5F8FA
Tinted page background
Border#CADAE3
Hairlines and dividers
Muted text#507E96
Captions on the surface
Accent#4D2926
Second voice, not a rival
Dark variant#2C4653
Hover, pressed, headers
Light variant#EEF3F6
Selected rows, tints
Dark surface#141F24
Dark-mode background
Hover#1C2B34
One step down in lightness
Pressed#0F181C
Two steps down
Disabled#59798A
Chroma pulled out
Focus ring#284C5F
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 #283f4b

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

Works well for
  • Body text and links on white
  • Charts, tags and secondary surfaces
  • Headers, footers and dark-mode surfaces
  • Brand accents, badges and data highlights
Use with care
  • Text on black or near-black surfaces
  • 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.

The muted chroma softens the association — it reads considered rather than loud, which suits long-form and data-heavy screens. 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
  • Weight78/100
  • 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#4B3428
Analogous left#284B45
Analogous right#282D4B
Split-complement 1#4B282D
Split-complement 2#4B4528
Triadic 1#4B283F
Triadic 2#3F4B28
Tetradic#45284B
On the wheel
Base+30°−30°+120°+240°+180°201°

#283f4b sits at 201°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red15.7%
Green24.7%
Blue29.4%
R · 0–255
40
0x28
G · 0–255
63
0x3f
B · 0–255
75
0x4b

CMYK percentages

Cyan46.7%
Magenta16.0%
Yellow0.0%
Key (black)70.6%

Total ink coverage is 133%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#283f4b text on a black background

contrast 1.90:1

Card sample

#283f4b text on a white background

contrast 11.04:1

Card sample

#283f4b on grey

10.07:1

#283f4b on its own surface

10.35:1

#283f4b on its dark surface

1.52:1

CSS3 live lab

Text font color

The quick brown fox

color: #283f4b;
Background color
Panel with #283f4b background
background-color: #283f4b;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #283f4b;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(40, 63, 75, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(40, 63, 75, 0.45);
Border & gradient
Gradient panel
border: 3px solid #283f4b;
background: linear-gradient(135deg, #283f4b, #28284B);
Gradient text

Gradient headline

background: linear-gradient(90deg, #283f4b, #31284B);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #283f4b;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #283f4b;
caret-color: #283f4b;
Left rule
Pull quote or callout
border-left: 4px solid #283f4b;
Ring + tint
Selected chip
background: #EEF3F6;
box-shadow: inset 0 0 0 2px #283f4b;
Conic badge
68%
background: conic-gradient(#283f4b 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #283f4b 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(40, 63, 75, 0.5)
rgb(40 63 75 / 50%)
#283f4b80
hsl(201 30% 23% / 50%)
color-mix(in srgb, #283f4b 50%, transparent)
Alpha8-digit hexFlat on white
10%#283f4b1a#EAECED
20%#283f4b33#D4D9DB
40%#283f4b66#A9B2B7
60%#283f4b99#7E8C93
80%#283f4bcc#53656F

Gradients from #283f4b

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, #3D6073, #283f4b 45%, #2C4653);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #283f4b, #201D37);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #283f4b, #4B3428);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #487187 0%, #283f4b 45%, #2C4653 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F5F8FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #3A6C60 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #33365F 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #2C4653 0%, transparent 65%), #283f4b;

Monochromatic scale

Palettes built from #283f4b

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.

#283f4b 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

Very dark values collapse into each other on cheap panels — leave more lightness between your darkest steps than the numbers suggest.

In dark mode

Too dim on dark surfaces at 1.90:1 — lift it to #4F7C94 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.

#283f4b, answered

What color is #283f4b?

#283f4b is a deep soft blue, closest to Dark Slate Gray (ΔE2000 9.7). It sits at 201° on the hue wheel with 30% saturation and 23% lightness, which reads as cool.

What is the RGB value of #283f4b?

rgb(40, 63, 75) — 40 red, 63 green and 75 blue out of 255, or 15.7% / 24.7% / 29.4% by channel.

What is #283f4b in HSL and HSV?

hsl(201, 30%, 23%) and hsv(201, 47%, 29%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #283f4b a light or a dark color?

It is a dark color. Relative luminance is 0.0451 and perceived brightness is 23%, so white text on it reaches 11.04:1.

Should I use black or white text on #283f4b?

White. It scores 11.04:1 against #283f4b, versus 1.90:1 for black — AAA at any size.

Is #283f4b accessible on a white background?

#283f4b on white scores 11.04:1, which clears AAA at every size.

What is the complementary color of #283f4b?

#4B3428 sits directly opposite on the wheel. Softer options are the split-complements #4B282D and #4B4528, which give the same contrast with far less vibration.

What colors go well with #283f4b?

For interface work: #F5F8FA as the surface, #CADAE3 for borders, #507E96 for secondary text, #4D2926 as an accent and #2C4653 for hover and pressed states. For a palette, the analogous pair #284B45 and #282D4B stays calm, while #4B3428 is the loudest partner.

What is #283f4b in CMYK for printing?

cmyk(47%, 16%, 0%, 71%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #283f4b warm or cool?

Cool — it scores 90 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #284B4A; nudged cooler, #27394C.

Which Tailwind color is closest to #283f4b?

The gray family — its 500 step is #6b7280, ΔE2000 20.2 away. That is a visible difference, so define #283f4b as a custom token rather than reaching for the built-in.

How do I use #283f4b in Tailwind CSS?

Inline it as an arbitrary value with bg-[#283f4b] or text-[#283f4b], 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 #283f4b with 50% opacity?

rgba(40, 63, 75, 0.5), or #283f4b80 in eight-digit hex. Over white that composites to #949FA5; over black, #142026.

Is #283f4b a web-safe color?

No. The nearest web-safe colour is #333333, ΔE2000 10.4 away. The palette only matters for legacy displays and some email clients now.

What does the color #283f4b 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 moderate chroma the association is present but not shouted.

What gradient works with #283f4b?

The safest is same-hue elevation: linear-gradient(135deg, #3D6073, #283f4b 45%, #2C4653). For more colour, a short hue run to #201D37 keeps it rich without turning muddy.

Work with #283f4b in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #283f4b at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.