Kelly Green (#4CBB17) is a light, highly saturated green hue. Kelly green is a bright, pure green associated with Ireland and St Patrick's Day.
In RGB it is made of 76 red, 187 green and 23 blue. Its HSL hue angle is 101° with 78% saturation and 41% lightness, while its perceptual OKLCH lightness is 70% with a chroma of 0.212. For print, a starting CMYK mix is 59% cyan, 0% magenta, 88% yellow and 27% black.
As a text color on white, Kelly Green has a contrast ratio of 2.49:1, which fails WCAG AA even for large text. On black it reaches 8.43:1 and passes AA for normal text. If you use Kelly Green as a background, put black (or very dark) text on it. The APCA lightness contrast is Lc 56 for black text and Lc -54 for white text.
Its perceptual complement is #D46AF1, close to orchid. Colors that look most similar are lime green, emerald, jade. People with red-green color blindness see kelly green quite differently (ΔE 14), so do not rely on it alone to signal meaning.