#0421FB Color

#0421FB is rgb(4, 33, 251) in RGB, hsl(233, 97%, 50%) in HSL, and about cmyk(98%, 87%, 0%, 2%) in CMYK. It has no registered color name of its own — the closest is Ultramarine Blue(caran D'ache) (#2111EF), very hard to tell apart at ΔE 4.52. White text is the more readable choice on this background.

#0421FB

HEX#0421FB

RGBrgb(4, 33, 251)

HSLhsl(233, 97%, 50%)

HSVhsv(233, 98%, 98%)

CMYKcmyk(98%, 87%, 0%, 2%)

OKLCHoklch(46.3% 0.298 264.5)

LABlab(31.73% 59.80 -106.17)

LCHlch(31.73% 121.86 299.39)

What #0421FB 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 #0421FB, ordered by CIE76 distance in CIELAB. Anything under about ΔE 2 is a difference most people cannot see.

Ultramarine Blue(caran D'ache)#2111EFΔE 4.52 Han Purple#5218FAΔE 8.73 Ultramarine#3F00FFΔE 10.06 Indigo (Color Wheel)#4000FFΔE 10.09 Blue#0000FFΔE 10.54 Medium Blue#0000CDΔE 14.48

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

#0421FB Channel Values

How #0421FB 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 4 · G 33 · B 251	8-bit channels as sent to the display
HSL	H 233° · S 97% · L 50%	Easiest model for building lighter and darker variants
HSV	H 233° · S 98% · V 98%	Matches the picker in most design tools
CMYK	C 98% · M 87% · Y 0% · K 2%	Approximate ink mix; confirm with an ICC profile before printing
Luminance	8.03:1 vs white · 2.62:1 vs black	WCAG 2.2 relative-luminance contrast ratios

Text Contrast & Accessibility

WCAG 2.2 contrast ratios for text on a #0421FB 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.

TextWhite text8.03:1AA normal AA large AAA normal

Fails AABlack text2.62:1AA normal AA large AAA normal

Need a specific ratio against another background? Open #0421FB in the contrast checker.

Colors That Go With #0421FB

Pairings derived from color-wheel relationships. The complementary color sits opposite #0421FB; 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 #0421FB

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 #0421FB.

How #0421FB 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#0421FB

Protanopia#1E1EFB

Protanomaly#161FFB

Deuteranopia#1A1AFB

Deuteranomaly#141DFB

Tritanopia#006767

Tritanomaly#0053B6

Achromatopsia#505050

Test a full palette in the color blindness simulator.

Using #0421FB in Code

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

CSS custom property--color-0421fb: #0421FB;

CSS backgroundbackground-color: #0421FB;

Tailwind configcolors: { 'color-0421fb': '#0421FB' }

SwiftUIColor(red: 0.016, green: 0.129, blue: 0.984)

Android XML<color name="color_0421fb">#0421FB</color>

SVG fillfill="#0421FB"

More Blue Colors

#0421FB 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

#0421FB Frequently Asked Questions

What color is #0421FB?

#0421FB is a mid-tone blue — rgb(4, 33, 251) in RGB and hsl(233, 97%, 50%) in HSL. It carries no registered color name of its own; the closest named color is Ultramarine Blue(caran D'ache) (#2111EF), which is very hard to tell apart at a CIE76 distance of 4.52.

What is the RGB value of #0421FB?

#0421FB is rgb(4, 33, 251) — red 4, green 33, and blue 251 on the 0-255 scale.

What is the CMYK value of #0421FB?

#0421FB converts to approximately cmyk(98%, 87%, 0%, 2%). CMYK output is a mathematical approximation for planning; confirm production print colors with your printer and ICC profile.

Should text on #0421FB be black or white?

White text is the more readable choice. #0421FB scores 8.03:1 against white and 2.62:1 against black, and WCAG 2.2 asks for at least 4.5:1 for normal body text.

Can I write #0421FB as a CSS color keyword?

No. #0421FB 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 blue (#0000FF) at a CIE76 distance of 10.54, which is visibly different.

Open #0421FB 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.