Sky Blue (#87CEEB) is a light, moderately saturated blue hue. Sky blue is the light blue of a clear afternoon sky, calm and optimistic.
In RGB it is made of 135 red, 206 green and 235 blue. Its HSL hue angle is 197° with 71% saturation and 73% lightness, while its perceptual OKLCH lightness is 81% with a chroma of 0.082. For print, a starting CMYK mix is 43% cyan, 12% magenta, 0% yellow and 8% black.
As a text color on white, Sky Blue has a contrast ratio of 1.74:1, which fails WCAG AA even for large text. On black it reaches 12.06:1 and passes AA for normal text. If you use Sky Blue as a background, put black (or very dark) text on it. The APCA lightness contrast is Lc 72 for black text and Lc -35 for white text.
Its perceptual complement is #F0B296, close to dusty rose. Colors that look most similar are baby blue, powder blue, silver. It looks fairly similar to people with red-green color blindness (ΔE 6), so its meaning mostly survives.