Ten thousand days
Yearly totals and pooled monthly profiles cannot answer a question about a specific day. With a date axis, the biggest review days in Amazon’s history turn out to be in January — not Prime Day, not Black Friday.
Daily series · 1996–2023
6 minUpdated August 2026The series
9,595 days with at least one review
The earlier aggregates gave yearly totals and pooled cyclical profiles but never a date axis, so no question about a specific day could be asked at all. This is the whole thing, from Mon, Jun 17, 1996 to Thu, Sep 14, 2023, aggregated to weeks so 28 years fit in one chart. The busiest week began Mon, Dec 30, 2019 with 2.1M reviews.
Reviews per week, 1996–2023
Weekly totals across all 33 categories. The final week is partial.
The rating series is only 61% covered. ts_daily_all masks avg_rating on thin category-days rather than dropping the row — a deliberate deviation from the suppression rule, and it affects 39.3% of the 238,342 category-day cells. Daily counts are complete; daily ratings are computed only from the cells that report one, which skews toward high-volume category-days. Read the count series freely and the rating series carefully.
The peaks
Amazon’s biggest review days are in January
Not Prime Day. Not Black Friday. Not Cyber Monday. Of the 25 highest-volume days since 2010, 13 fall in January and 12 in December — the review wave arrives when the gift is opened and used, not when it is bought. The single busiest day in the corpus is Sun, Jan 5, 2020 with 333K reviews.
The 15 biggest review days since 2010
Daily totals across all categories.
Amber is January, plum December, blue everything else.
The annual cycle
One year, day by day
Every calendar day, indexed so 100 is that year’s average day, averaged over 2015–2022 so the growth trend is removed. The peak is Dec 28 at 138 and the floor is Nov 26 at 75 — a 1.8× swing within a single year, invisible in monthly aggregates.
Day-of-year profile, indexed
100 = the average day of that year. Averaged across 2015–2022.
The sawtooth is the weekday cycle, which does not align to calendar dates across years and so partially averages out. The step down at the end of December and the cliff in early January are the gift wave beginning and the backlog clearing.