Tailwind CSS v3 color

Tailwind slate-500 #64748B

Tailwind CSS v3's slate-500 is #64748B. It is a grayish blue in the blue family. In OKLCH it sits at lightness 0.554, chroma 0.041 and hue 257.4°. The nearest CSS named color is slategray (#708090), ΔE2000 5.6 away.

Relative luminance
0.1706
OKLCH L · C · h
0.554 · 0.041 · 257.4
Best text
White 4.75:1
Hue family
Blue
Inspect this color Check contrast

#64748B color codes

HEX
#64748B
RGB
rgb(100, 116, 139)
HSL
hsl(215, 16%, 47%)
OKLCH
oklch(0.554 0.041 257.4)
OKLab
oklab(0.554 -0.009 -0.040)
CIELAB (D65)
L* 48.34, a* -0.33, b* -14.51
XYZ (D65)
X 16.16, Y 17.06, Z 26.86
CMYK (naive)
cmyk(28%, 17%, 0%, 45%)

CIELAB and XYZ use the D65 white point; CSS lab() uses D50, so paste the OKLCH or HEX value into stylesheets. CMYK here is a plain formula with no press profile.

Legibility

Contrast: is #64748B accessible?

White text on it reaches 4.75:1, passing AA. Black text manages only 4.41:1, enough for large text only.

WCAG 2 gives the same ratio whichever color is the text; APCA does not, so its Lc changes sign and size with polarity.

Open the Contrast System

  • Black text on it

    4.41:1

    • AA fails
    • AA large passes
    • AAA fails
    • APCA Lc +31

  • White text on it

    4.75:1

    • AA passes
    • AA large passes
    • AAA fails
    • APCA Lc −78

  • As text on black

    4.41:1

    • AA fails
    • AA large passes
    • AAA fails
    • APCA Lc −28

  • As text on white

    4.75:1

    • AA passes
    • AA large passes
    • AAA fails
    • APCA Lc +73

Nearest versions that pass 4.5:1

  • For text on white

    #64748B 4.75:1

    It already reaches 4.75:1 on white, so no change is needed.

  • For text on black

    #67778E 4.60:1

    Lightening its OKLCH lightness from 0.55 to 0.56 reaches 4.60:1 on black, keeping the hue.

    Compare both in the Contrast System

Checking another pair? Use the Contrast Checker.

Studio

Adjust #64748B live

Move lightness, chroma and hue in OKLCH, or drag on the map. The map is every lightness and chroma at the current hue: sRGB inside the solid area, Display P3 out to the dashed line.

The studio needs JavaScript.

Scale

Shades and tints of #64748B

Eleven OKLCH lightness steps at this hue, each with its contrast against white and black. #64748B sits at step 600.

  1. 50#EFF6FF
    White
    1.08
    Black
    19.29
  2. 100#DFECFF
    White
    1.19
    Black
    17.57
  3. 200#C9D9F0
    White
    1.43
    Black
    14.66
  4. 300#AFBFD7
    White
    1.86
    Black
    11.25
  5. 400#92A3BB
    White
    2.56
    Black
    8.17
  6. 500#77879F
    White
    3.65
    Black
    5.75
  7. 600This color#64748B
    White
    4.75
    Black
    4.41
  8. 700#4A596E
    White
    7.13
    Black
    2.94
  9. 800#334154
    White
    10.37
    Black
    2.02
  10. 900#1E293A
    White
    14.64
    Black
    1.43
  11. 950#0D1624
    White
    18.14
    Black
    1.15

Under each step, white and black text on it; a bold figure passes 4.5:1.

Tailwind CSS v3 slate scale

The real Tailwind palette, for comparison with the computed ramp above.

  1. 50#F8FAFC
    White
    1.04
    Black
    20.07
  2. 100#F1F5F9
    White
    1.09
    Black
    19.16
  3. 200#E2E8F0
    White
    1.23
    Black
    17.03
  4. 300#CBD5E1
    White
    1.48
    Black
    14.14
  5. 400#94A3B8
    White
    2.56
    Black
    8.19
  6. 500This color#64748B
    White
    4.75
    Black
    4.41
  7. 600#475569
    White
    7.57
    Black
    2.77
  8. 700#334155
    White
    10.35
    Black
    2.02
  9. 800#1E293B
    White
    14.62
    Black
    1.43
  10. 900#0F172A
    White
    17.85
    Black
    1.17
  11. 950#020617
    White
    20.17
    Black
    1.04

Gamut

How vivid #64748B can get

At its lightness and hue, sRGB reaches OKLCH chroma 0.200; #64748B uses 20% of it. Display P3, which many recent phones and laptops show, reaches 0.255 there: 27% more.

0.00.20.40.60.80.20.40.60.8 460480500520540560580600620
  • sRGB
  • Display P3
  • Rec. 2020
  • Dominant wavelength
OKLCH chroma
0.041
sRGB edge
0.200
Display P3 edge
0.255
Rec. 2020 edge
0.269
Dominant wavelength
478 nm
Excitation purity
21%
Chromaticity
x 0.2689, y 0.2840
  • This color#64748B
  • Most vivid in sRGB#006CE4
  • Most vivid in Display P3oklch(0.554 0.255 257.4)

On a screen without Display P3 the last tile shows the sRGB edge instead.

Use the wider color where screens show it
.accent {
  color: #64748b;
}
@media (color-gamut: p3) {
  .accent { color: color(display-p3 0 0.3839 0.976); }
}

Mixing

Mixing #64748B

Each row is the same mix worked out in a different space, with the halfway color at its end. sRGB, which older CSS gradients use, can sag gray or dark in the middle; OKLab keeps the lightness steps even; OKLCH holds chroma and hue as it goes.

White #FFFFFF

  • sRGB50%#B2BAC5
  • OKLab50%#AFB7C4
  • OKLCH50%#AFB7C4

Black #000000

  • sRGB50%#323A46
  • OKLab50%#222932
  • OKLCH50%#222932

Its complement #807058

  • sRGB50%#727272
  • OKLab50%#727373
  • OKLCH50%#5C7B6E
In CSS
/* A gradient and a mix, worked out in OKLCH */
background: linear-gradient(in oklch, #64748b, white);
color: color-mix(in oklch, #64748b 50%, white);

In use

#64748B in an interface

A button, a link, a heading, a focused field, an icon and a chart line in this color, on a light page and a dark one. Each check is a WCAG 2 contrast minimum: 1.4.3 for text, 1.4.11 for the rest.

Light page

  • Button labelText, 4.5:14.75:1 Passes
  • Link and body-size textText, 4.5:14.75:1 Passes
  • Large headingLarge text, 3:14.75:1 Passes
  • Icons, borders and focus ringsNon-text, 3:14.75:1 Passes

Dark page

  • Button labelText, 4.5:14.75:1 Passes
  • Link and body-size textText, 4.5:13.93:1 Fails
  • Large headingLarge text, 3:13.93:1 Passes
  • Icons, borders and focus ringsNon-text, 3:13.93:1 Passes

For text on this page, the nearest shade that passes is #6E7E96 4.53:1

Color vision

How #64748B looks with color blindness

Tritanopia changes it most, ΔE2000 12.8; protanopia changes it least, 3.2.

Simulated with Machado et al. (2009) at full severity, in linear light.

Simulate a whole page What each type sees

  • Protanopia

    No working red (long-wavelength) cones

    #6C758C ΔE2000 3.2

    Close match

    Reads as grayish blue

  • Deuteranopia

    No working green (medium-wavelength) cones

    #68718A ΔE2000 3.6

    Close match

    Reads as grayish blue

  • Tritanopia

    No working blue (short-wavelength) cones

    #59797C ΔE2000 12.8

    Distinct

    Reads as grayish cyan

  • Achromatopsia

    No cone color vision; lightness only

    #737373 ΔE2000 10.9

    Distinct

    Reads as gray

Pairing check

Checked against its complement, #807058. Their lightness contrast is only 1.00:1, so where hue collapses, add a label, icon or pattern.

VisionThe pairΔE2000Verdict
Normal vision#64748B · #80705823.0Stays distinct
Protanopia#6C758C · #77705623.7Stays distinct
Deuteranopia#68718A · #7B745924.9Stays distinct
Tritanopia#59797C · #876B6A30.3Stays distinct
Achromatopsia#737373 · #7272720.4Easily confused

Harmony

Color harmonies for #64748B

Its complement is #807058, a grayish amber, on the warm side of the wheel.

Hue rotations in OKLCH, mapped into sRGB by trimming chroma so hue and lightness stay put.

Open the Harmony Studio
  • Base#64748B
  • Complement#807058

Complementary

Open in Harmony Studio
  • −30°#5A7886
  • Base#64748B
  • +30°#71708A

Analogous

Open in Harmony Studio
  • Base#64748B
  • +120°#896A6A
  • +240°#687961

Triadic

Open in Harmony Studio
  • Base#64748B
  • +150°#886C5F
  • +210°#757559

Split-complementary

Open in Harmony Studio

Code

Design tokens

Ready-to-paste tokens in six formats. Rename them to fit your system.

CSS custom property

:root {
  --color-slate-500: #64748b;
}

Tailwind config

// tailwind.config.js — already built in as slate-500;
// pin the v3 value explicitly like this:
module.exports = {
  theme: {
    extend: {
      colors: {
        slate: { 500: '#64748b' },
      },
    },
  },
};

Tailwind v4 theme

/* app.css — Tailwind CSS v4 */
@import "tailwindcss";

@theme {
  /* v4 has its own slate-500; this pins the v3 value. */
  --color-slate-500: oklch(0.554 0.041 257.4);
}

Design token (W3C DTCG)

{
  "color": {
    "slate-500": {
      "$type": "color",
      "$value": {
        "colorSpace": "srgb",
        "components": [0.3922, 0.4549, 0.5451],
        "hex": "#64748b"
      },
      "$description": "Tailwind CSS v3 slate-500"
    }
  }
}

SwiftUI color

import SwiftUI

enum Palette {
    static let slate500 = Color(.sRGB, red: 0.392, green: 0.455, blue: 0.545, opacity: 1)
}

Jetpack Compose color

import androidx.compose.ui.graphics.Color

object Palette {
    val Slate500 = Color(0xFF64748B)
}

Matches

The nearest match in each system

The closest CSS name, Tailwind shade, RAL Classic paint and Crayola crayon by ΔE2000; under 2 is hard to tell apart side by side. RAL and Crayola values approximate physical colors.

Neighbors

The eight nearest colors on this site by ΔE2000, closest first. Under 2 is hard to tell apart side by side.

Tools

Open #64748B in the tools

Each opens over this page. More colors live in the Color Library, and every color page is listed on the hub.