Private browser utility / Color & Design

Complementary Color Finder

Runs entirely in your browser - no upload, no sign-up.

Live workspaceLocal processing

Base color

Accepts 3- or 6-digit HEX, RGB, and HSL values.

Complementary pair

#2563eb + #ebad25

Base#2563eb

RGB: rgb(37, 99, 235)
HSL: hsl(221.2 83.2% 53.3%)

Complement#ebad25

RGB: rgb(235, 173, 37)
HSL: hsl(41.2 83.2% 53.3%)

70 / 30 usage preview

Let one color lead and use its complement as the accent.

2.59:1

70%

30%

Complementary hue does not guarantee readable text contrast. Use this pair for accents, not text, without testing.

CSS variables

Paste the pair into a stylesheet and rename the tokens for your design system.

:root {
  --color-base: #2563eb;
  --color-complement: #ebad25;
}

01 / Overview

What is a complementary color finder?

A complementary color finder takes one digital color and returns the hue 180 degrees opposite it on the HSL color wheel. Enter a HEX, RGB, or HSL value to see both colors, compare their contrast, preview a practical 70/30 pairing, and copy the result as CSS.

How to use

01
Enter a base color
Type a 3- or 6-digit HEX value, an RGB color, or an HSL color, or use the visual color picker.
02
Read the opposite hue
The finder rotates the HSL hue by 180 degrees and displays both colors in HEX, RGB, and HSL.
03
Check the pairing
Use the 70/30 preview and contrast ratio to judge how the colors behave together.
04
Copy the result
Copy either HEX value or the ready-made CSS variables for your project.

Who it's for

Interface designers can turn a brand color into a focused accent candidate for calls to action and status highlights.
Illustrators can find the opposite hue for shadows, focal points, and controlled visual tension.
Front-end developers can copy the pair as CSS custom properties without converting color formats by hand.
Brand teams can test a two-color relationship before expanding it into a larger palette.

The calculation runs in your browser and updates as you type. It preserves the base color's saturation and lightness while rotating only its hue, so the result is an exact HSL complement rather than a random contrasting color.

FAQ

Is this complementary color finder free?

Yes. You can find, preview, swap, and copy complementary colors without signing up or paying. The calculation is small enough to run instantly in your browser, so there is no server usage limit or upload step.

Are my colors uploaded?

No. Your color is parsed and converted locally in your browser. CanDoYa does not need to upload the value to calculate its complementary hue, preview the pair, or format the CSS variables.

What are the limits of this complementary color finder?

It accepts opaque HEX, RGB, and HSL colors in the sRGB range. It does not process alpha transparency, CMYK or spot inks, paint mixing, display gamut differences, or colors sampled directly from an image.

How do you calculate the complementary color?

The finder converts the input to HSL, adds 180 degrees to the hue, wraps the result around 360 degrees, and keeps saturation and lightness unchanged. It then converts that opposite hue back to RGB and HEX for use in browsers and design tools.

What is the complementary color of blue?

It depends on the exact blue. Pure HSL blue at 240 degrees pairs with yellow at 60 degrees, but a blue closer to cyan produces a complement closer to orange-red. Enter the precise HEX or RGB value to avoid relying on a broad color name.

Why is the complement of gray still gray?

Gray has zero saturation, which means it has no visible hue. Rotating its stored HSL hue by 180 degrees changes the hue number but not the rendered color. Add saturation first if you need a visibly different opposite hue.

Do complementary colors always have accessible contrast?

No. Opposite hue and readable luminance contrast measure different things. The finder shows the WCAG contrast ratio for the generated pair, but you should use a dedicated contrast checker for every text size, weight, state, and final background.

How is this different from a full color palette generator?

This tool answers one focused question: what hue sits exactly opposite this color? A palette generator explores several harmony rules, tints, shades, and larger schemes. Use this finder when you want a fast two-color relationship with no extra options.