Color #21303B Color / Colour Code #21303B
This page shows the hex color code for color #21303b (#21303B). The colour is a blue tone with 28% saturation and 18% lightness. Explore its conversions, colour palettes, gradients, accessibility data, and CSS code below.
Color Conversions
Accessibility Contrast
WCAG contrast ratios for #21303B against common backgrounds.
Complementary Colors
#21303B paired with its color wheel opposite for maximum contrast.
Analogous Colors
Hues at 175, 205, and 235 degrees for harmonious combinations.
Triadic Palette
Three colors at 205, 325, and 85 degrees.
Color Palettes Using #21303B
Five shades at lightness levels 15% through 85% while keeping hue at 205 and saturation at 28%. Use the darkest shade for text and the lightest for backgrounds to build a cohesive single-hue design system.
Adjacent hues from 205 to 250 degrees create a warm, unified palette. This analogous scheme works for marketing materials, seasonal campaigns, and any design that needs visual warmth without clashing colors.
Combines the base color at hue 205 with its complement at 25 and two adjacent cool tones. This split-complementary approach provides strong visual contrast while remaining more balanced than a pure complementary scheme.
Five evenly spaced hues at 40% saturation and 80% lightness. Pastels are gentle on the eyes and work well for dashboards, onboarding screens, category tags, and any interface where multiple distinct colors are needed without visual aggression.
Shades & Tints of #21303B
Lightness variations at hue 205 and 28% saturation.
CSS Gradients with #21303B
Design Use Cases for #21303B
Muted Accent Color
With 28% saturation, #21303B has a subtle, sophisticated quality. This level of desaturation works well for secondary buttons, inactive states, subtle borders, and backgrounds that need a hint of color without being distracting. Muted colors communicate restraint and professionalism.
Deep Accent & Text Color
#21303B at 18% lightness is dark enough for readable body text on light backgrounds while retaining its blue character. Use for headings, emphasized text, or deep accent borders. It provides contrast without the harshness of pure black.
Trust & Professional Identity
#21303B sits in the blue range (hue 205). Blue is the world's most popular color for corporate identities because it conveys trust, stability, and competence. Use it for navigation bars, link text, form focus states, and any element where user confidence matters. Financial, healthcare, and technology brands rely heavily on this hue range.
Gradient Pairing
Create a gradient from #21303B (hue 205) to its complement at hue 25. For a subtler effect, try pairing with an analogous color at hue 235. Use CSS: background: linear-gradient(135deg, #21303b, #3b2c21);
CSS Code for #21303B
Similar Colors
Colors visually similar to #21303B based on RGB, lightness, and hue variations.
Use This Color in Design Tools
Apply #21303B across image editing and color design tools.
About Color #21303B (#21303B)
#21303B is a blue color (colour) with RGB channel values of 33 red, 48 green, and 59 blue. The blue channel is dominant with a relatively balanced channel distribution. In HSL terms, the hue sits at 205 degrees with 28% saturation and 18% lightness, placing it in the cool range of the colour spectrum.
The perceived brightness of #21303B is 45/255 using the ITU-R BT.601 luma formula (0.299R + 0.587G + 0.114B). This appears dark to the human eye, so pair it with light text for adequate readability. For print production, the CMYK equivalent is 44% cyan, 19% magenta, 0% yellow, and 77% key (black).
The WCAG contrast ratio of #21303B against white is 13.54:1 and against black is 1.55:1. This exceeds the AAA requirement (7:1) for normal text on white, making it excellent for body text and small UI labels on light backgrounds.
The complementary colour #3B2C21 creates maximum visual tension when paired with #21303B. For more harmonious color combinations, use the analogous colours #213B39 and #21233B, which sit 30 degrees on either side of the hue wheel. To build a complete design system, start with the monochromatic scale above for consistent shade variations, then add one complementary or triadic accent for interactive elements.
How to Explore Color #21303B
- Enter your color value in HEX format.
- The tool converts it to RGB, HSL, CMYK format in real time.
- Copy the converted value to your clipboard.
What is HEX to RGB, HSL, CMYK color conversion
Converting from HEX to RGB, HSL, CMYK translates a color value between two different color models. Different color models are used in web design (HEX, RGB), print (CMYK), and color theory (HSL, HSV).
Related Tools & Colors
Frequently Asked Questions
- What color / colour is #21303B?
- #21303B is Color #21303B, a blue color (colour) with RGB(33, 48, 59), HSL(205, 28%, 18%), and CMYK(44%, 19%, 0%, 77%). Its perceived brightness is 45/255.
- Is #21303B accessible for text?
- Against white, #21303B has a contrast ratio of 13.54:1 (passes AA for normal text). Against black, it has 1.55:1 (fails AA). Use the contrast checker tool for custom background pairings.
- What colours pair well with #21303B?
- The complementary colour is #3B2C21 (hue 25). For subtle color combinations, use analogous colours #213B39 and #21233B. The triadic palette adds #3B2130 and #303B21 for vibrant variety.
- How do I use #21303B in CSS?
- Use any format: color: #21303b; or rgb(33, 48, 59); or hsl(205, 28%, 18%). For CSS custom properties: --color-primary: 205 28% 18%; then use it as hsl(var(--color-primary)).
- Is this color / colour explorer free?
- Yes, completely free with no signup required. All colour calculations run in your browser. You can explore any valid hex color code, not just the pre-generated palette.