Booming Greenfinch
Booming Greenfinch (#4A9E21) is a true green with a jewel character. It carries the deep, saturated richness of a gemstone. Authoritative and slightly formal, it works well for type and heavy UI elements. Its HSL profile (100°, 65%, 37%) places it in the balanced band at a mid lightness. It works across type, buttons, and borders, saturated enough to feel deliberate but balanced enough to not fight the rest of the palette. For a confident two-color system, pair it with its complementary violet. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Imitative-onomatopoeic origin — present-participle of boom, sharing root with Dutch bommen. As a color modifier, booming implies a saturated-and-loud-and-confident quality where the hue announces itself with full visual amplitude. Sits at the bold-and-resonant end of the grid, parallel to resounding and thunderous.
Chloris chloris, the European finch whose males in breeding plumage are yellow-green with bright yellow wing bars — common in British and Continental hedgerow gardens until trichomonosis collapsed populations in the 2000s. The color refers to a male European greenfinch in spring: a saturated, slightly muted yellow-green with the matte finish of carotenoid-pigmented feathers.
Closest matches
The nearest named color in three reference sources, ranked by perceptual distance (ΔE76 in CIELAB). ΔE < 1 is imperceptible to most viewers; ΔE > 10 is clearly different. When two sources point to the same hex they’re merged into one tile; click any to open that color’s page.
Variations
Click any swatch to exploreHarmonies
Accessibility
How this color appears to viewers with the four major color-vision-deficiency types. Computed via the Machado (2009) physiologically-based model. If a tile matches the original, the color reads the same to that viewer.
The color used as foreground text against pure white and pure black, with the contrast ratio and WCAG 2.1 grade. Aim for AA (4.5:1) for body text and AA Large (3:1) for 18 pt+ headlines; AAA (7:1) is the gold standard for long-form reading surfaces.
Wide gamut
The CSS Color 4 wide-gamut form of this color. Both swatches render the same color on every display — the P3 form only diverges from sRGB when a designer pushes channels outside sRGB's reach.
Moderately saturated colors gain a small bump in P3 — the difference is usually visible side-by-side on wide-gamut hardware but won't change the character of the color.