#21A3E4 Color

#21A3E4 is rgb(33, 163, 228) in RGB, hsl(200, 78%, 51%) in HSL, and about cmyk(86%, 29%, 0%, 11%) in CMYK. It has no registered color name of its own — the closest is Vivid Cerulean (#00AAEE), very hard to tell apart at ΔE 3.62. Black text is the more readable choice on this background.

#21A3E4

HEX#21A3E4

RGBrgb(33, 163, 228)

HSLhsl(200, 78%, 51%)

HSVhsv(200, 86%, 89%)

CMYKcmyk(86%, 29%, 0%, 11%)

OKLCHoklch(67.9% 0.141 237.5)

LABlab(62.76% -17.00 -43.03)

LCHlch(62.76% 46.27 248.45)

What #21A3E4 Is Called

Most hex codes have no name: there are 16.7 million of them and a few thousand registered names. These are the named colors nearest to #21A3E4, ordered by CIE76 distance in CIELAB. Anything under about ΔE 2 is a difference most people cannot see.

Vivid Cerulean#00AAEEΔE 3.62 Microsoft Blue#00A2EDΔE 5.55 Twitter Blue#26A7DEΔE 5.98 Rich Electric Blue#0892D0ΔE 6.45 Picton Blue#45B1E8ΔE 7.82 Blue Jeans#5DADECΔE 8.28

Browse the full index of named colors A-Z or every blue in the library.

#21A3E4 Channel Values

How #21A3E4 breaks down in each color model. Hue is measured in degrees around the color wheel; saturation, lightness, and the CMYK inks are percentages.

Model	Channels	Notes
RGB	R 33 · G 163 · B 228	8-bit channels as sent to the display
HSL	H 200° · S 78% · L 51%	Easiest model for building lighter and darker variants
HSV	H 200° · S 86% · V 89%	Matches the picker in most design tools
CMYK	C 86% · M 29% · Y 0% · K 11%	Approximate ink mix; confirm with an ICC profile before printing
Luminance	2.83:1 vs white · 7.42:1 vs black	WCAG 2.2 relative-luminance contrast ratios

Text Contrast & Accessibility

WCAG 2.2 contrast ratios for text on a #21A3E4 background. AA requires 4.5:1 for normal text and 3:1 for large text; AAA requires 7:1. Contrast is one check, not a full accessibility review.

Fails AAWhite text2.83:1AA normal AA large AAA normal

TextBlack text7.42:1AA normal AA large AAA normal

Need a specific ratio against another background? Open #21A3E4 in the contrast checker.

Colors That Go With #21A3E4

Pairings derived from color-wheel relationships. The complementary color sits opposite #21A3E4; analogous colors sit beside it; triadic and split-complementary sets spread evenly around the wheel. Select any swatch for its own breakdown.

Base

Complementary

Analogous

Analogous

Triadic

Triadic

Split comp.

Split comp.

Tints & Shades of #21A3E4

Lighter tints and darker shades built by moving the lightness channel while holding hue and saturation, which is what you want for hover states, backgrounds, and text variants.

Tints

Shades

Want a full 50-950 ramp with semantic roles? Generate design tokens from #21A3E4.

How #21A3E4 Looks with Color Vision Deficiency

Simulated with the Viénot, Brettel & Mollon LMS projection model. Anomalous types are rendered as partial versions of the matching dichromacy, which is an approximation rather than a per-person clinical model.

Typical#21A3E4

Protanopia#9696E4

Protanomaly#799CE4

Deuteranopia#8989E5

Deuteranomaly#6E94E5

Tritanopia#00ADAD

Tritanomaly#00A9C5

Achromatopsia#9A9A9A

Test a full palette in the color blindness simulator.

Using #21A3E4 in Code

Copy-ready declarations for the places this color usually ends up.

CSS custom property--color-21a3e4: #21A3E4;

CSS backgroundbackground-color: #21A3E4;

Tailwind configcolors: { 'color-21a3e4': '#21A3E4' }

SwiftUIColor(red: 0.129, green: 0.639, blue: 0.894)

Android XML<color name="color_21a3e4">#21A3E4</color>

SVG fillfill="#21A3E4"

More Blue Colors

#21A3E4 sits in the blue family. These are its neighbours across that family's full range, each with its own breakdown.

000024 fafaff 00002e f9fafb 000033 f8fafc 000038 f8f8ff 000042 f5faff 000047 f5f5ff 002147 007dfa 0f52ba 1c39bb 2a3439 372aac 4e3cc3 64609a 7abdff 979aaa b8dbff d6d6ff

#21A3E4 Frequently Asked Questions

What color is #21A3E4?

#21A3E4 is a mid-tone blue — rgb(33, 163, 228) in RGB and hsl(200, 78%, 51%) in HSL. It carries no registered color name of its own; the closest named color is Vivid Cerulean (#00AAEE), which is very hard to tell apart at a CIE76 distance of 3.62.

What is the RGB value of #21A3E4?

#21A3E4 is rgb(33, 163, 228) — red 33, green 163, and blue 228 on the 0-255 scale.

What is the CMYK value of #21A3E4?

#21A3E4 converts to approximately cmyk(86%, 29%, 0%, 11%). CMYK output is a mathematical approximation for planning; confirm production print colors with your printer and ICC profile.

Should text on #21A3E4 be black or white?

Black text is the more readable choice. #21A3E4 scores 2.83:1 against white and 7.42:1 against black, and WCAG 2.2 asks for at least 4.5:1 for normal body text.

Can I write #21A3E4 as a CSS color keyword?

No. #21A3E4 is not one of the CSS color keywords, so it has to be written as a hex, rgb() or hsl() value. The closest keyword is deepskyblue (#00BFFF) at a CIE76 distance of 11.52, which is visibly different.

Open #21A3E4 in a Tool

Hex to RGB Hex to HSL Hex to CMYK Hex to OKLCH Hex to Pantone Build a palette Make a gradient

Keep exploring: every blue in the color library, the guide to shades of blue, or the full color library.