Complementary Color Generator
Choose a base color to calculate a two-color complementary pair on the HSL hue wheel. The second color sits 180 degrees from the first while saturation and lightness stay fixed.
Preparing your workspace…
A reproducible hue relationship
Changing the base color immediately recalculates the pair. A red base produces its cyan hue opposite; this describes a mathematical HSL relationship, not a physical pigment mixture or a claim about personal color preferences.
Use a pair with restraint
Try one color for large surfaces and its complement as a small accent. Equal amounts of highly saturated opposites can compete for attention. Copy the HEX values, download CSS custom properties or save a JSON palette to keep the exact result.
Check contrast separately
Complementary hue does not guarantee readable text. Test the actual foreground and background at the sizes you plan to use. A neutral gray has no chromatic hue difference, so its complementary calculation remains gray. This generator operates locally without an image or account.
Common questions
Is the second color guaranteed to be accessible?
No. Accessibility depends on contrast, text size and use; a 180-degree hue relationship alone is insufficient.
Why do grayscale colors repeat?
Their saturation is zero. Rotating a hue with zero saturation produces the same gray.