{
  "version": "2026-11",
  "readOn": "2026-11-11",
  "label": "ESTIMATE. Amazon publishes no conversion from Best Sellers Rank to sales. This curve comes from a published third-party fit plus our own stated range. It is not fitted to any Amazon data.",
  "scope": "Kindle Store paid eBooks, Amazon.com. No published curve for paperbacks was read, so paperback ranks are not estimated.",
  "central": {
    "formula": "daily sales = 100000 / BSR",
    "k": 100000,
    "exponent": 1,
    "source": "Old tails: a crude power law fit on ebook sales",
    "sourceDate": "April 2014 (Win-Vector Blog, reposted on R-bloggers)",
    "sourceUrl": "https://tagteam.harvard.edu/hub_feeds/1988/feed_items/613092/content",
    "sourceRange": "The source says its fit looks plausible for ranks of about 200 to 150,000; outside that the figure is a rougher guess.",
    "sourceSays": "A typical ebook ranked at position 100,000 sells about 1 copy a day; daily units are roughly 100,000 divided by the sales rank."
  },
  "range": {
    "lowFactor": 0.5,
    "highFactor": 2,
    "basis": "Our own assumption, stated here: published estimates disagree by about 2x either way. Example: a Just Kindle Books table puts rank 1,000 at 120 a day against the central 100.",
    "crossCheckUrl": "https://www.justkindlebooks.com/?p=200391"
  },
  "validRanks": { "min": 10, "max": 2000000 }
}