Color Palette Generator

A color palette generator is a tool that applies color theory principles to automatically produce a set of harmonious colors from a single starting hue. Instead of guessing which colors complement each other, you pick one base color and let the generator derive the rest using mathematically defined relationships on the color wheel. The result is a ready-to-use palette for web design, UI/UX work, branding, illustration, or any creative project that requires consistent, visually balanced colors.

This color palette generator works entirely in the HSL (Hue, Saturation, Lightness) color space. Because HSL separates the hue angle from brightness and saturation, shifting colors by precise degrees on the color wheel is straightforward arithmetic — a fact that makes it the preferred model for programmatic palette generation. The tool accepts any hex color as input, converts it to HSL internally, applies the chosen harmony rule, then converts the resulting HSL values back to hex codes you can copy directly into CSS, design software, or code.

Six palette types are available: Complementary, Analogous, Triadic, Tetradic (Square), Split Complementary, and Monochromatic. Each type produces a distinct visual mood and serves different design goals. The tool also exports the palette as CSS custom properties (--color-1, --color-2, etc.) so you can paste the snippet directly into a stylesheet with zero manual work.

Every palette calculation in this tool begins by converting your hex input to HSL. The hex string is split into three pairs of hexadecimal digits representing the red, green, and blue channels, each normalized to the 0–1 range. From those normalized RGB values the tool derives Hue (H), Saturation (S), and Lightness (L).

Lightness is the average of the largest and smallest channel values. Saturation depends on lightness: when L is greater than 0.5 the divisor is 2 − max − min; otherwise it is max + min. Hue is determined by which channel holds the maximum value and is expressed in degrees from 0° to 360°.

Converting back from HSL to HEX uses the chroma–intermediate method. The chroma C and intermediate value X together define the RGB sector, and the match offset m shifts all three channels to the correct lightness level. The final R, G, B values are each multiplied by 255 and rounded before being formatted as two-digit hex pairs.

Each harmony type positions colors at specific angular relationships on the 360° HSL hue wheel. The tool generates five colors for the fixed-count palettes (Complementary, Triadic, Tetradic, Split Complementary) and between 3 and 10 colors for the variable-count palettes (Analogous and Monochromatic).

Complementary palettes also add a darker variant (L − 15) and a lighter variant (L + 15) of both the base and complementary hue to give you five usable swatches. The Triadic type reduces saturation by 20 percentage points on its muted swatch, giving a softer accent alongside the vivid triadic pair.

The Analogous palette type is the most mathematically transparent of all six options. Given a base hue H and a requested count of n colors, the tool spaces the swatches evenly around H in 30° increments, with H always at the center of the range. The formula for the hue of each color at position i (starting at 0) is shown below.

For example, choosing 5 analogous colors centered on red (H = 0°) produces hues at −60°, −30°, 0°, 30°, and 60°. Because the HSL engine normalizes any negative angle — ((H % 360) + 360) % 360 — the −60° becomes 300° (magenta-violet) and −30° becomes 330° (rose). The result is a smooth band of related hues that appear adjacent on the color wheel, which is exactly why analogous palettes feel calm and cohesive. The 30° step is fixed in the code; adjusting the number of colors widens or narrows the total arc (n × 30°) rather than changing the step size.

Because saturation and lightness are held constant across all analogous swatches, the palette maintains uniform brightness, making it easy to swap colors for different UI states without altering the visual weight of a design element.

The Monochromatic palette keeps hue and saturation identical across every swatch and varies only the Lightness channel. The generator distributes lightness values evenly from 20% (near-black) to 80% (near-white), which avoids the harsh extremes of pure black and pure white while still providing a wide tonal range. The formula is a simple linear interpolation across the available lightness band.

For a 5-color monochromatic palette the lightness values are 20%, 35%, 50%, 65%, and 80%. A 3-color palette yields 20%, 50%, and 80%. A 10-color palette produces increments of about 6.67 percentage points. The step size automatically adjusts so the first swatch is always the darkest (20%) and the last is always the lightest (80%), regardless of how many swatches you choose.

Monochromatic schemes are extremely versatile in interface design. The darkest shades work well for text and borders; mid-tones serve as background fills and card surfaces; the lightest shades pair well with subtle hover states or disabled controls. Because every color shares the same hue, the palette stays cohesive and on-brand even when elements vary dramatically in visual weight.

Generating a palette is only the first step; applying it well in a real project requires a few guiding principles from color theory and interface design. A common rule of thumb is the 60-30-10 rule: 60% of a design's color area goes to a dominant neutral or background color, 30% to a secondary color that provides structure, and 10% to an accent color that draws attention to key actions like buttons or alerts. Using the CSS custom properties exported by this tool makes it trivial to implement this split in a stylesheet.

When using a Complementary palette, reserve the complementary hue for high-contrast highlights rather than large blocks of color. Full-saturation complementary pairs like blue and orange can be overwhelming at equal visual weight; reducing saturation or lightness on one of them restores balance. The tool already provides darker and lighter variants of both the base and complementary hue to give you this flexibility immediately.

For dashboards and data-rich interfaces, Triadic and Tetradic palettes offer enough distinct hues to color-code multiple data series without any two series looking ambiguous. The Triadic muted swatch (base hue at S − 20%) is particularly useful as a background fill that keeps the chart area visually quiet while the two vivid triadic hues pop as data colors.

Accessibility is a critical consideration with any palette. WCAG 2.1 requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text against the background. Monochromatic palettes generated from mid-saturation bases often struggle here — use the darkest shade (L ≈ 20%) for text on white backgrounds, or the lightest shade (L ≈ 80%) for text on dark-mode surfaces. Always verify contrast ratios with a dedicated color contrast tool before shipping.

The CSS Variables output from this generator is designed to slot directly into a design token system. Drop the :root { } block into a global stylesheet and reference var(--color-1) through var(--color-5) throughout your component library. Changing the base color later requires updating only the generator — all downstream tokens update automatically.