Reporting Methodology & The Saturday Anchor Rule
The BLK Bestsellers List compiles point-of-sale retail book sales data in 7-day cycles starting on Sunday morning and ending at Saturday midnight.
The Saturday Anchor Rule
Because sales figures are aggregated in weekly chunks, a single week's sales are never split across calendar months. An entire week's sales volume is assigned to the reporting month anchored by the ending Saturday. For example, the July 2026 BLK list reflects sales tracked from June 07, 2026 through July 04, 2026, while the August 2026 list covers July 05, 2026 through August 01, 2026.
Key Calendar Rules for Publishers & Authors:
- 4-Week vs. 5-Week Months: Depending on how Saturdays land in the calendar, a BLK Bestseller reporting period consists of either 4 weeks (28 days) or 5 weeks (35 days).
- Cross-Month Weeks: A sales week running from June 28 to July 04 is counted in the July reporting period because July 4th is the Saturday anchor date.
- Standardization: AALBC's monthly BLK Bestsellers list aligns strictly with these periods to guarantee complete data fidelity across point-of-sale reports.
BLK Reporting Periods (February 2024 – December 2028)
Select a year to view exact sales tracking date ranges and weekly counts:
| BLK Bestseller Month | Sales Tracking Period (Sun – Sat) | Reporting Weeks |
|---|---|---|
| January 2027 | Dec 06, 2026 – Jan 02, 2027 | 4 Weeks |
| February 2027 | Jan 03, 2027 – Feb 06, 2027 | 5 Weeks |
| March 2027 | Feb 07, 2027 – Mar 06, 2027 | 4 Weeks |
| April 2027 | Mar 07, 2027 – Apr 03, 2027 | 4 Weeks |
| May 2027 | Apr 04, 2027 – May 01, 2027 | 4 Weeks |
| June 2027 | May 02, 2027 – Jun 05, 2027 | 5 Weeks |
| July 2027 | Jun 06, 2027 – Jul 03, 2027 | 4 Weeks |
| August 2027 | Jul 04, 2027 – Aug 07, 2027 | 5 Weeks |
| September 2027 | Aug 08, 2027 – Sep 04, 2027 | 4 Weeks |
| October 2027 | Sep 05, 2027 – Oct 02, 2027 | 4 Weeks |
| November 2027 | Oct 03, 2027 – Nov 06, 2027 | 5 Weeks |
| December 2027 | Nov 07, 2027 – Dec 04, 2027 | 4 Weeks |
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