Complementary Color Calculator
Find the complementary (opposite) color of any HEX code instantly. Rotates the hue by 180° and shows both swatches with copyable HEX and RGB values.
Complementary pair
What is the Complementary Color Calculator?
The Complementary Color Calculator finds the color directly opposite yours on the color wheel by rotating its hue 180° in HSL space.
- Accurate 180° hue rotation in HSL
- Base and complement shown side by side
- Copyable HEX and RGB for both colors
- Great for high-contrast accents
- Works with any HEX input
- Private, client-side calculation
How to use the Complementary Color Calculator
- 1
Pick or type your base color as a HEX code.
- 2
The calculator rotates the hue 180° to find the complement.
- 3
Compare the two swatches side by side.
- 4
Copy the complementary HEX or RGB value with one click.
About the Complementary Color Calculator
The Complementary Color Calculator finds the color directly opposite yours on the color wheel by rotating its hue 180° in HSL space. Complementary pairs sit at maximum contrast, which is exactly why designers reach for them when an accent, button or highlight needs to pop against its background.
Enter a base color and the tool shows both swatches side by side with their HEX and RGB codes, each copyable in one click. Because the calculation is pure color-wheel math, the result follows the same rule taught in every color-theory course.
Everything is computed locally in your browser — no uploads, no account, and it works offline once loaded.
Frequently asked questions
What is a complementary color?
A complementary color is the one directly opposite another on the color wheel — 180° away in hue. Red and cyan, blue and orange, and yellow and purple are classic complementary pairs. Placed together they create the strongest possible color contrast.
How do you calculate a complementary color?
Convert the color to HSL, add 180 to its hue (wrapping around 360°), then convert back. Saturation and lightness stay the same, so only the hue flips to the opposite side of the wheel. This tool does that conversion automatically.
When should I use complementary colors?
Use them for elements that must stand out: call-to-action buttons, badges, links and data highlights. Because the contrast is intense, it is usually best to let one color dominate and use its complement sparingly as an accent rather than 50/50.
Why do complementary colors sometimes clash or vibrate?
Two fully saturated complements placed edge to edge can appear to shimmer, an optical effect called simultaneous contrast. To calm it, lower the saturation of one color, add a neutral border between them, or give one much more area than the other.
Is the complement of a color unique?
In the HSL/RGB model, yes — each hue has exactly one opposite 180° away. Note that this differs slightly from painters' complementary pairs, which are based on the older red-yellow-blue wheel, so digital and pigment complements can look a little different.
Guides for Complementary Color Calculator
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