How many colors does a website use?

Two counts answer the question. A site's CSS writes many exact values: the median site has 113, half of the sites between 58 to 189, and the most 1,085. Many sit in rules that match nothing on the page, and many are near-identical shades. Merged where they lie within 0.04 of each other in OKLab, and counted only where they reach an element, they shrink to the colors a visitor can tell apart: 18 on the median home page, between 12 to 25 for half of the sites. The most common range is 20 to 29 colors.

Of the 18 colors in use on the median page, 9 have a hue and the rest are greys; greys carry 73% of the color, weighed by what each covers. The colored ones group into 3 hue families on the median site, each a color with its darker, lighter and hover shades.

The counts spread widely. 15% of the home pages use fewer than ten colors and 6% use 40 or more; the busiest uses 170. In the CSS the range is wider still: 8.4% of the sites write fewer than 25 distinct values, 4.6% write 400 or more, and one writes 1,085. Unused rules count among the values: a framework's whole palette can sit in the CSS while the page uses a few of its colors. The study shows which frameworks the sites carry.

A short palette of chosen colors, as How many colors a website palette needs suggests, fits what real sites do: a few families, each spread over shades, and greys for most of the page. Recolor maps a palette onto a page the same way, family by family, so a few swatches cover all 113 values of the median site; Strength, neutral tint and overrides shows how. To count your own site's colors, load it into Recolor: the foot of the palette shows how many colors in use it found, counted as this page counts them.

Recolor's engine read each home page with its scripts off: style sheets, style attributes and color attributes, every color as sRGB with transparency aside. Colors only an image or a script carries are not in the count. The study has the other results and the data, the methodology every definition, and Which sites load the same counts for the sites Recolor tests itself on.