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red · warm

#a63721

a dark, vivid red · warm · closest name: Firebrick

Token name suggestion: Shadow Cherry

RGB
166, 55, 33
HSL
10°, 67%, 39%
CMYK
0, 67, 80, 35
Luminance
0.1095

#a63721 is a dark vivid red, 10° on the wheel and 11/100 on the cool side. Put white text on it (6.58:1). As text it scores 6.58:1 on white — safe at any size. Nearest name is Firebrick, nearest Tailwind family is red.

hsl(10 67% 39%)rgb(166 55 33)Base step 700AA inkWarm

At a glance

Every number on this page in one read: what #a63721 is made of, how bright it looks, and which way it leans.

Hex
#a63721
Hue
10°
red
Saturation
67%
vivid
Lightness
39%
dark
Brightness
65%
HSV value
Perceived
39%
weighted brightness
Luminance
0.1095
WCAG relative
Temperature
Warm
11/100 cool
Color family
Red
Tone
Vivid
Best ink
White
6.58:1
Closest name
Firebrick
ΔE2000 4.8
Chroma
58.4
LCH, 0–130ish
OKLCH L
0.495
perceptual lightness
Tailwind
red
500 · ΔE 16.9
Web-safe
#993333
nearest of 216
Where it sits
Hue10° of 360°
Saturation67%
Lightness39%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #a63721.

Temperature
Warm ← → Cool11% cool

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

Luminance by channel
Red74%
Green25%
Blue1%

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

Every format

HEX#a63721
HEX (8-digit)#a63721ff
RGBrgb(166, 55, 33)
RGBArgba(166, 55, 33, 1)
HSLhsl(10, 67%, 39%)
HSV / HSBhsv(10, 80%, 65%)
HWBhwb(10 13% 35%)
CMYKcmyk(0%, 67%, 80%, 35%)
LABlab(39.5 44.5 37.8)
LCHlch(39.5 58.4 40.4)
OKLCHoklch(0.495 0.150 33.1)
XYZ (D65)xyz(17.37, 10.95, 2.64)
Decimal10893089
Display P3color(display-p3 0.651 0.216 0.129)
Web-safe#993333

Copy-ready code

every platformclick to select
/* CSS */
color: #a63721;
background-color: #a63721;
/* CSS custom property */
--brand: #a63721;
/* Tailwind (arbitrary) */
class="text-[#a63721] bg-[#a63721]"
/* SCSS */
$brand: #a63721;
/* SwiftUI */
Color(red: 0.651, green: 0.216, blue: 0.129)
/* UIKit */
UIColor(red: 0.651, green: 0.216, blue: 0.129, alpha: 1)
/* Android XML */
<color name="brand">#A63721</color>
/* Android Compose */
Color(0xFFA63721)
/* Flutter */
Color(0xFFA63721)
/* Python / OpenCV (BGR) */
(33, 55, 166)
/* Python / PIL (RGB) */
(166, 55, 33)
/* Java AWT */
new Color(166, 55, 33)
/* .NET */
Color.FromArgb(255, 166, 55, 33)
/* OpenGL / Unity (0–1) */
(0.6510f, 0.2157f, 0.1294f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{166,55,33}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #a63721 85%, white);
border-color: color-mix(in oklab, #a63721 40%, transparent);
/* theme-aware in one line */
color: light-dark(#6A2315, #EED7D3);
/* relative colour syntax */
--hover: hsl(from #a63721 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: #FBF5F3;
  --brand-100: #F8EAE8;
  --brand-200: #F1D1CA;
  --brand-300: #ECAEA1;
  --brand-400: #E38573;
  --brand-500: #DA5D44;
  --brand-600: #CC4429;
  --brand-700: #a63721;
  --brand-800: #882D1B;
  --brand-900: #632418;
  --brand-950: #3E170F;
  --brand: #a63721;
  --brand-ink: #ffffff;
  --brand-surface: #FAF5F4;
  --brand-border: #EDC7C0;
  --brand-hover: #882D1B;
  --brand-pressed: #6A2315;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #241614;
    --brand-ink: #EED7D3;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#FBF5F3',
        100: '#F8EAE8',
        200: '#F1D1CA',
        300: '#ECAEA1',
        400: '#E38573',
        500: '#DA5D44',
        600: '#CC4429',
        700: '#a63721',
        800: '#882D1B',
        900: '#632418',
        950: '#3E170F',
        DEFAULT: '#a63721',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #FBF5F3,
  '100': #F8EAE8,
  '200': #F1D1CA,
  '300': #ECAEA1,
  '400': #E38573,
  '500': #DA5D44,
  '600': #CC4429,
  '700': #a63721,
  '800': #882D1B,
  '900': #632418,
  '950': #3E170F,
);
$brand-base: #a63721;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#FBF5F3", "$type": "color" },
      "100": { "$value": "#F8EAE8", "$type": "color" },
      "200": { "$value": "#F1D1CA", "$type": "color" },
      "300": { "$value": "#ECAEA1", "$type": "color" },
      "400": { "$value": "#E38573", "$type": "color" },
      "500": { "$value": "#DA5D44", "$type": "color" },
      "600": { "$value": "#CC4429", "$type": "color" },
      "700": { "$value": "#a63721", "$type": "color" },
      "800": { "$value": "#882D1B", "$type": "color" },
      "900": { "$value": "#632418", "$type": "color" },
      "950": { "$value": "#3E170F", "$type": "color" }
    },
    "brandInk": { "$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 #a63721 · 6.58:1
Use #ffffffAA at every size, AAA for large text only.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 6.58:1 · recommended
AA pass · AA large pass · AAA fail
Aa
Black text · 3.19:1
AA fail · AA large pass · AAA fail
Reading the other direction: #a63721 as text scores 6.58:1 on white and 3.19:1 on black.
Best tinted ink on it, if plain black or white feels flat: #FBEDEA at 5.77:1.

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
#a63721 · 6.58:1
AA on whitealready passes
#a63721
The quick fox
#9D341F · 7.13:1
AAA on white−2% L
#9D341F
The quick fox
#D04529 · 4.57:1
AA on black+10% L
#D04529
The quick fox
#E17A66 · 7.18:1
AAA on black+25% L
#E17A66

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #A63721 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
#a63721 on white: 6.58:1
AA ✓ pass · AA-large · AAA
Aa
#a63721 on black: 3.19:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #a63721 as text on that neutral, and that neutral as text on #a63721.

NeutralRatioBoth directions
White6.58:1AaAa
Slate 506.29:1AaAa
Slate 1006.01:1AaAa
Slate 2005.34:1AaAa
Slate 3004.43:1AaAa
Slate 4002.57:1AaAa
Slate 5001.38:1AaAa
Slate 6001.15:1AaAa
Slate 7001.57:1AaAa
Slate 8002.22:1AaAa
Slate 9002.71:1AaAa
Black3.19:1AaAa
Colour vision deficiency
true color
protanopia · #574E1E
deuteranopia · #72661C
tritanopia · #B71633

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. #a63721 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.

#FBF5F3
#F8EAE8
#F1D1CA
#ECAEA1
#E38573
#DA5D44
#CC4429
#a63721
#882D1B
#632418
#3E170F
Base = 700Lightest = 50 · #FBF5F3Darkest = 950 · #3E170FText step on white = 600
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 0.038 33.1);
  --brand-100: oklch(0.94 0.060 33.1);
  --brand-200: oklch(0.88 0.090 33.1);
  --brand-300: oklch(0.80 0.117 33.1);
  --brand-400: oklch(0.72 0.138 33.1);
  --brand-500: oklch(0.64 0.150 33.1);
  --brand-600: oklch(0.56 0.150 33.1);
  --brand-700: oklch(0.48 0.141 33.1);
  --brand-800: oklch(0.40 0.126 33.1);
  --brand-900: oklch(0.32 0.105 33.1);
  --brand-950: oklch(0.24 0.083 33.1);
}

Colors that work with #a63721

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#FAF5F4
Tinted page background
Border#EDC7C0
Hairlines and dividers
Muted text#9B584B
Captions on the surface
Accent#1EAEA2
Second voice, not a rival
Dark variant#6A2315
Hover, pressed, headers
Light variant#FBEDEA
Selected rows, tints
Dark surface#241614
Dark-mode background
Hover#882D1B
One step down in lightness
Pressed#6A2315
Two steps down
Disabled#B18D86
Chroma pulled out
Focus ring#C23519
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 #a63721

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
  • Status meaning — pair it with an icon or label, never colour alone
  • 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.

urgentappetisingboldphysical

Red arrives before the rest of the page does. It raises attention and appetite, which is why it runs food, sport and clearance pricing.

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 universal error colour. Use it as a brand accent and users may read a warning that is not there.

Reads as
  • FormalityHigh
  • EnergyMedium-high
  • Weight61/100
  • TemperatureWarm
  • ApproachabilityHigh

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#2190A6
Analogous left#A6214E
Analogous right#A67921
Split-complement 1#21A679
Split-complement 2#214EA6
Triadic 1#21A637
Triadic 2#3721A6
Tetradic#4EA621
On the wheel
Base+30°−30°+120°+240°+180°10°

#a63721 sits at 10°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red65.1%
Green21.6%
Blue12.9%
R · 0–255
166
0xa6
G · 0–255
55
0x37
B · 0–255
33
0x21

CMYK percentages

Cyan0.0%
Magenta66.9%
Yellow80.1%
Key (black)34.9%

Total ink coverage is 182%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#a63721 text on a black background

contrast 3.19:1

Card sample

#a63721 text on a white background

contrast 6.58:1

Card sample

#a63721 on grey

6.01:1

#a63721 on its own surface

6.09:1

#a63721 on its dark surface

2.66:1

CSS3 live lab

Text font color

The quick brown fox

color: #a63721;
Background color
Panel with #a63721 background
background-color: #a63721;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #a63721;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(166, 55, 33, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(166, 55, 33, 0.45);
Border & gradient
Gradient panel
border: 3px solid #a63721;
background: linear-gradient(135deg, #a63721, #A69021);
Gradient text

Gradient headline

background: linear-gradient(90deg, #a63721, #9BA621);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #a63721;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #a63721;
caret-color: #a63721;
Left rule
Pull quote or callout
border-left: 4px solid #a63721;
Ring + tint
Selected chip
background: #FBEDEA;
box-shadow: inset 0 0 0 2px #a63721;
Conic badge
68%
background: conic-gradient(#a63721 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #a63721 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(166, 55, 33, 0.5)
rgb(166 55 33 / 50%)
#a6372180
hsl(10 67% 39% / 50%)
color-mix(in srgb, #a63721 50%, transparent)
Alpha8-digit hexFlat on white
10%#a637211a#F6EBE9
20%#a6372133#EDD7D3
40%#a6372166#DBAFA6
60%#a6372199#CA877A
80%#a63721cc#B85F4D

Gradients from #a63721

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, #D64A2F, #a63721 45%, #6A2315);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #a63721, #8C831C);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #a63721, #2190A6);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #DB6048 0%, #a63721 45%, #6A2315 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #FAF5F4, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #D0296F 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #BF9926 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #6A2315 0%, transparent 65%), #a63721;

Monochromatic scale

Palettes built from #a63721

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.

#a63721 in the real world

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

Industries
Food and drinkEntertainmentRetailSport
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 3.19:1 — lift it to #D04529 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.

#a63721, answered

What color is #a63721?

#a63721 is a dark vivid red, closest to Firebrick (ΔE2000 4.8). It sits at 10° on the hue wheel with 67% saturation and 39% lightness, which reads as warm.

What is the RGB value of #a63721?

rgb(166, 55, 33) — 166 red, 55 green and 33 blue out of 255, or 65.1% / 21.6% / 12.9% by channel.

What is #a63721 in HSL and HSV?

hsl(10, 67%, 39%) and hsv(10, 80%, 65%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #a63721 a light or a dark color?

It is a dark color. Relative luminance is 0.1095 and perceived brightness is 39%, so white text on it reaches 6.58:1.

Should I use black or white text on #a63721?

White. It scores 6.58:1 against #a63721, versus 3.19:1 for black — AA at any size.

Is #a63721 accessible on a white background?

#a63721 on white scores 6.58:1, which clears AA at every size but not AAA.

What is the complementary color of #a63721?

#2190A6 sits directly opposite on the wheel. Softer options are the split-complements #21A679 and #214EA6, which give the same contrast with far less vibration.

What colors go well with #a63721?

For interface work: #FAF5F4 as the surface, #EDC7C0 for borders, #9B584B for secondary text, #1EAEA2 as an accent and #6A2315 for hover and pressed states. For a palette, the analogous pair #A6214E and #A67921 stays calm, while #2190A6 is the loudest partner.

What is #a63721 in CMYK for printing?

cmyk(0%, 67%, 80%, 35%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #a63721 warm or cool?

Warm — it scores 11 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #A64D21; nudged cooler, #A81F3B.

Which Tailwind color is closest to #a63721?

The red family — its 500 step is #ef4444, ΔE2000 16.9 away. That is a visible difference, so define #a63721 as a custom token rather than reaching for the built-in.

How do I use #a63721 in Tailwind CSS?

Inline it as an arbitrary value with bg-[#a63721] or text-[#a63721], 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 #a63721 with 50% opacity?

rgba(166, 55, 33, 0.5), or #a6372180 in eight-digit hex. Over white that composites to #D39B90; over black, #531C11.

Is #a63721 a web-safe color?

No. The nearest web-safe colour is #993333, ΔE2000 7.6 away. The palette only matters for legacy displays and some email clients now.

What does the color #a63721 mean?

As a red, it reads urgent, appetising, bold. Red arrives before the rest of the page does. It raises attention and appetite, which is why it runs food, sport and clearance pricing. At this chroma the effect is amplified — it will dominate whatever sits beside it.

What gradient works with #a63721?

The safest is same-hue elevation: linear-gradient(135deg, #D64A2F, #a63721 45%, #6A2315). For more colour, a short hue run to #8C831C keeps it rich without turning muddy.

Work with #a63721 in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #a63721 at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.