Color #EFFF43 Color / Colour Code #EFFF43
This page shows the hex color code for color #efff43 (#EFFF43). The colour is a yellow tone with 100% saturation and 63% lightness. Explore its conversions, colour palettes, gradients, accessibility data, and CSS code below.
Color Conversions
Accessibility Contrast
WCAG contrast ratios for #EFFF43 against common backgrounds.
Complementary Colors
#EFFF43 paired with its color wheel opposite for maximum contrast.
Analogous Colors
Hues at 35, 65, and 95 degrees for harmonious combinations.
Triadic Palette
Three colors at 65, 185, and 305 degrees.
Color Palettes Using #EFFF43
Five shades at lightness levels 15% through 85% while keeping hue at 65 and saturation at 100%. Use the darkest shade for text and the lightest for backgrounds to build a cohesive single-hue design system.
Adjacent hues from 65 to 110 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 65 with its complement at 245 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 #EFFF43
Lightness variations at hue 65 and 100% saturation.
CSS Gradients with #EFFF43
Design Use Cases for #EFFF43
High-Impact Accent
With 100% saturation, #EFFF43 is highly vivid. Reserve this for elements that need maximum attention: primary action buttons, notification badges, error states, or promotional banners. Use sparingly alongside neutral tones to avoid visual fatigue.
Soft Accent & Highlight
With 63% lightness, #EFFF43 has a softer, more approachable quality. It works well for hover states, subtle highlights, progress indicators, and secondary UI elements. This lightness range is particularly effective for tag backgrounds and status indicators.
Attention & Optimism
#EFFF43 is in the yellow spectrum (hue 65). Yellow attracts attention faster than any other color. Use it for warning labels, featured content markers, star ratings, and tooltip backgrounds. Pair with dark text since yellow often fails contrast checks against white.
Gradient Pairing
Create a gradient from #EFFF43 (hue 65) to its complement at hue 245. For a subtler effect, try pairing with an analogous color at hue 95. Use CSS: background: linear-gradient(135deg, #efff43, #5242ff);
CSS Code for #EFFF43
Similar Colors
Colors visually similar to #EFFF43 based on RGB, lightness, and hue variations.
Use This Color in Design Tools
Apply #EFFF43 across image editing and color design tools.
About Color #EFFF43 (#EFFF43)
#EFFF43 is a yellow color (colour) with RGB channel values of 239 red, 255 green, and 67 blue. The green channel is dominant by a ratio of 3.8:1 over the weakest channel. In HSL terms, the hue sits at 65 degrees with 100% saturation and 63% lightness, placing it in the neutral-to-cool range of the colour spectrum.
The perceived brightness of #EFFF43 is 229/255 using the ITU-R BT.601 luma formula (0.299R + 0.587G + 0.114B). This means it appears bright to the human eye and is best paired with dark text for readability. For print production, the CMYK equivalent is 6% cyan, 0% magenta, 74% yellow, and 0% key (black).
The WCAG contrast ratio of #EFFF43 against white is 1.10:1 and against black is 19.06:1. This does not meet AA requirements on white. Use it on dark backgrounds where it achieves 19.06:1, or use it exclusively for decorative purposes.
The complementary colour #5242FF creates maximum visual tension when paired with #EFFF43. For more harmonious color combinations, use the analogous colours #FFB042 and #91FF42, 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 #EFFF43
- 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 #EFFF43?
- #EFFF43 is Color #EFFF43, a yellow color (colour) with RGB(239, 255, 67), HSL(65, 100%, 63%), and CMYK(6%, 0%, 74%, 0%). Its perceived brightness is 229/255.
- Is #EFFF43 accessible for text?
- Against white, #EFFF43 has a contrast ratio of 1.10:1 (fails AA for normal text). Against black, it has 19.06:1 (passes AA). Use the contrast checker tool for custom background pairings.
- What colours pair well with #EFFF43?
- The complementary colour is #5242FF (hue 245). For subtle color combinations, use analogous colours #FFB042 and #91FF42. The triadic palette adds #42EFFF and #FF42EF for vibrant variety.
- How do I use #EFFF43 in CSS?
- Use any format: color: #efff43; or rgb(239, 255, 67); or hsl(65, 100%, 63%). For CSS custom properties: --color-primary: 65 100% 63%; 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.