Why is it called a double complementary palette?

Because the rectangle is two complementary pairs sharing a wheel: the base and its opposite, plus the two hues 90 degrees either side. The classic tetradic color scheme and the double complementary palette are the same shape.

How do I keep four colors from looking chaotic?

Treat them as two pairs rather than four equals. Let one pair dominate the surface and the primary accent, and keep the second pair for secondary accents so three of the four hues stay quiet.

Can I adjust the angles between the four colors?

No. The four color rectangle harmony is fixed at 90, 180 and 270 degrees, and only the base changes the placement. A square arrangement is the same tool started from a different hue.

Which of the four should carry text?

Whichever the contrast checker approves against its background. Equal-weight hues rarely pass on their own, so darken one leg with the shades tool before assigning it to text.

Can I drop down to three colors later?

Yes, and often you should. Copy the legs that earned their place into the triadic generator or the palette locker, where a smaller set is easier to govern.

Tetradic Palette Generator

Color

#3B82F6

#d54b97

#c17400

#00a875

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Palette Sorter

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The tetradic palette generator derives four hues from one base: the base plus 90°, 180° and 270°, forming the wheel's rectangle. It is the widest standard harmony here, and it returns exactly four colors.

What is Tetradic Palette Generator?

A tetradic palette generator draws the wheel's rectangle: base, base plus 90, base plus 180 and base plus 270. Read another way, that is a double complementary palette, two complementary pairs sharing one wheel, which is why the four color rectangle harmony offers more vocabulary than any other standard scheme. The richness cuts both ways, though. Four strong hues at equal weight compete, and the geometry itself gives no hierarchy to settle the fight, so this is the rule that most rewards discipline.

The rotation is applied in OKLCH, and hue is the only coordinate that moves. Lightness and chroma come from the base, so all four swatches share a single weight and differ only in where they sit on the wheel, which keeps the tetradic color scheme flat and predictable. Because OKLCH is perceptually even, the rectangle's corners land where the eye expects them. Where the base sits near the ends of the lightness range, the derived values keep its weight rather than darkening or lightening on their own.

The geometry is fixed at 90, 180 and 270 degrees. The rectangle cannot be stretched or rotated except by changing the base.
The count is fixed at four. There is no count control and no fifth colour.
No contrast check. Equal-weight hues still need verifying before they carry text.
No ordering or sorting: the strip keeps derivation order, base then plus 90 then plus 180 then plus 270.
No lightness or chroma controls. The base is the only input, so any ramps are built afterwards with the tints and shades tools.

Treat the rectangle as two pairs rather than four equals. Let one complementary pair carry the dominant load, surface and primary accent, and hold the second pair in reserve for secondary accents, links and states. That reading turns the tetradic color scheme from a shouting match into a system, and it is why the double complementary palette keeps appearing in design systems that need four hue families without descending into rainbow. A rough proportion of seventy, twenty, seven and three works because the eye reads the two largest hues as structure and the two smallest as accents.

Four hues is also the point at which a palette starts to need governance rather than selection. Check the arrangement against real content instead of the swatch row, because four voices only work while three of them stay quiet. If four prove one too many, the triadic generator is the same idea with a point removed, and it is usually the more manageable scheme.

The rectangle is also a useful frame for a brand system with fixed accents, because the shape is anchored to the base and the two pairs stay a known distance from the brand hue. In practice that makes it possible to reserve one pair for product surfaces and the other for marketing, without either drifting into an unrelated set. Rotating the base lets the same proportions be tried at different temperatures, so the shape can be kept while the mood is swapped, and the whole rectangle can be reproduced later from the base value alone.

How to use Tetradic Palette Generator

Set the base color with the picker or by typing a hex value.
Read the four swatches: base, +90°, +180°, +270°.
Split the rectangle into two pairs and assign roles before copying values.

When to use Tetradic Palette Generator vs related tools

Use the tetradic generator when a scheme genuinely needs four hue families anchored to one colour. The triadic generator is the same geometry with a point removed and is easier to govern, the split-complementary generator is the quieter three-colour option, and the 10-color palette generator lets you compare these rules side by side. Confirm which legs can carry text with the contrast checker, and use the palette sorters to expose the structure of the strip.

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