{"name":"ReadMyBrowser entropy model","version":"2.0.0","updated":"2026-08-05","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"attribution":"Data from ReadMyBrowser (https://readmybrowser.com), maintained by FusionStudios. Entropy figures are ReadMyBrowser's own estimates, not measured population statistics; see https://readmybrowser.com/methodology.","documentation":"https://readmybrowser.com/methodology","disclaimer":"These are ReadMyBrowser's own illustrative estimates, reasoned from how many values each signal can take and how unevenly they are distributed. They are NOT measured population statistics. ReadMyBrowser collects no visitor data and therefore has no population to measure against. For a measured comparison see coveryourtracks.eff.org or amiunique.org.","method":"Each signal is estimated independently, then summed. Summing assumes independence, which is false for signals describing the same device, so the reported total is capped.","cappedAtBits":33,"capReason":"Adding per-signal estimates assumes the signals are independent, and they are not: several of them describe the same device. The total is therefore capped at 33 bits, roughly 8.6 billion combinations, which is already more than the number of people online. Anything past that ceiling is arithmetic rather than information.","uncappedSumBits":42.3,"signals":[{"key":"ua","label":"User agent","estimatedBits":10,"basis":"Carries browser, major version, platform and architecture in one string, though Chrome's User-Agent Reduction keeps shrinking what is left in it."},{"key":"screen","label":"Screen size and colour depth","estimatedBits":4.8,"basis":"A handful of resolutions cover most visitors, but the long tail is genuinely varied. Colour depth adds almost nothing, since browsers converged on reporting 24."},{"key":"dpr","label":"Device pixel ratio","estimatedBits":1.5,"basis":"Dominated by 1, 2 and 3, with the fractional values from Windows scaling and Android splitting the remainder."},{"key":"tz","label":"Timezone","estimatedBits":3,"basis":"A few hundred IANA zone names exist but are used very unevenly, so a common zone is cheap and a rare one is revealing."},{"key":"lang","label":"Language list","estimatedBits":2.5,"basis":"The ordering carries more than the first entry: one common language is near-universal, a specific ordered list of three is not."},{"key":"cores","label":"CPU threads","estimatedBits":1.8,"basis":"Concentrated on 4, 8, 12 and 16, and capped or reduced outright by Safari and Tor Browser."},{"key":"mem","label":"Device memory","estimatedBits":1.2,"basis":"The specification allows only six values and caps them at 8, which was the point of specifying it that way."},{"key":"touch","label":"Touch points","estimatedBits":1,"basis":"Effectively a yes or no for most visitors, so it splits the population roughly in half rather than finely."},{"key":"webgl","label":"WebGL renderer","estimatedBits":7,"basis":"A long driver-supplied string naming the graphics chip and often its driver, which splits visitors far more finely than any browser-level value."},{"key":"canvas","label":"Canvas rendering","estimatedBits":8,"basis":"How a device rasterises identical text and shapes depends on GPU, driver, fonts and anti-aliasing, so small hardware differences produce completely different hashes."},{"key":"platform","label":"Platform","estimatedBits":1.5,"basis":"About five platform families cover nearly everyone; the value is in the rare ones."}]}