How are the 140 CSS color names defined?

CSS Level 4 defines 148 named colors (including transparent and rebeccapurple). The 140 most commonly referenced set comes from the X11 color list and SVG specification, adopted by all modern browsers.

How is 'closest color' calculated?

The tool computes the Euclidean distance in RGB color space: sqrt((r1-r2)² + (g1-g2)² + (b1-b2)²). This is a simple approximation; perceptual color spaces like CIELAB give more accurate 'looks similar' results but are more complex.

Can I use CSS color names in production?

Yes. All 140 CSS named colors are fully supported in every modern browser and can be used in CSS, HTML, SVG, and JavaScript. They are a convenient alternative to hex codes when readability matters.

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Color Name Finder

Find the closest CSS named color for any hex or RGB value.

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Enter any color as a hex code or via RGB sliders and instantly discover the closest CSS named color from the full set of 140 standard CSS color names. The tool shows the exact match or nearest neighbor by Euclidean distance in RGB space, displays the top 5 nearest named colors with swatches and distance values, and provides a searchable grid of all 140 CSS color names. Ideal for designers, front-end developers, and anyone who wants a human-readable name for a color.

使い方

1 Type a hex color code (e.g. #3a86ff) into the hex input or click the color picker.
2 Alternatively, drag the R, G, B sliders to compose a color.
3 The closest CSS named color is shown immediately.
4 The top 5 nearest colors are listed with swatches and distance values.
5 Scroll down to browse or search the full grid of 140 CSS color names.

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