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 2026 | Dec 07, 2025 – Jan 03, 2026 | 4 Weeks |
| February 2026 | Jan 04, 2026 – Feb 07, 2026 | 5 Weeks |
| March 2026 | Feb 08, 2026 – Mar 07, 2026 | 4 Weeks |
| April 2026 | Mar 08, 2026 – Apr 04, 2026 | 4 Weeks |
| May 2026 | Apr 05, 2026 – May 02, 2026 | 4 Weeks |
| June 2026 | May 03, 2026 – Jun 06, 2026 | 5 Weeks |
| July 2026 | Jun 07, 2026 – Jul 04, 2026 | 4 Weeks |
| August 2026 | Jul 05, 2026 – Aug 01, 2026 | 4 Weeks |
| September 2026 | Aug 02, 2026 – Sep 05, 2026 | 5 Weeks |
| October 2026 | Sep 06, 2026 – Oct 03, 2026 | 4 Weeks |
| November 2026 | Oct 04, 2026 – Nov 07, 2026 | 5 Weeks |
| December 2026 | Nov 08, 2026 – Dec 05, 2026 | 4 Weeks |
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