Complementary colors sit opposite each other on the color wheel. Red and green. Blue and orange. Yellow and purple. Placed side by side, they intensify each other. The effect is optical, not just aesthetic. Stare at a red patch and then look at a white wall, and you will see a faint green afterimage. The eye seeks balance, and complementary pairs provide it.

Designers use complements to create strong contrast. A blue interface with orange call-to-action buttons makes those buttons impossible to miss. But the combination can also vibrate, especially at full saturation. Many designers soften one color, using a muted complement against a saturated one. This keeps the contrast without the visual buzz. Complementary schemes work well for sports teams, flags, and packaging that needs to stand out on a shelf.

Using complements well

• Pair a saturated color with a muted complement.
• Use complements for emphasis, not for large areas.
• Check contrast for accessibility.
• Consider cultural associations of each hue.

Complementary colors are not automatically good together. The proportions matter. A small amount of orange against a field of blue usually works better than an even split.