#51C8EB · #FFFFFF
Four independent scores (read the one that fits your goal): Readability 19/100 (fail) · Harmony 85/100 (complementary) · Distinguishable 85/100 (easy to tell apart) · Match 5/100 (different). There is no single “good/bad” — a pair can clash for text yet be great for an outfit.
Sky Blue and White are very different (ΔE 43). They have near-opposite hues (166° apart) and their lightness is different, giving a clear light/dark split.
Sky Blue text on White: 1.94:1 (Fail); White text on Sky Blue: 1.94:1 (Fail). Neither meets AA at body size — nudging one color to #01819E clears it.
Complementary — complementary — a recognised, balanced pairing (harmony 85/100). This is about how they look together (clothing, interiors, branding), independent of text contrast.
Not at body size — the best direction is only 1.9:1, below the 4.5:1 minimum. Nudging one colour to #01819E clears AA.
Their CIE76 ΔE is about 43 — very different.
clearly different colours (ΔE 43).
Explore each color: Sky Blue #51C8EB · White #FFFFFF · Shades: Sky Blue shades · White shades · Contrast checker →