Date & Time
Count birthdays and list names by calendar month across years
Group the example birthday dates by month number while ignoring year.
Why SUMIFS date bounds fail across decades—and how MONTH() solves it
COUNTIFS(Dates, ">=2026-05-01", Dates, "<=2026-05-31") only counts May 2026—it misses employees born in May 1984, May 1992, and May 2001!
Extracting MonthNum = MONTH(B2) (1 = Jan through 12 = Dec) strips the year cleanly so COUNTIF, SUMIF, and FILTER group every May birthday or multi-year December seasonal peak together across any century.
| Employee (A) | BirthDate (B) | BirthMonth = MONTH(B) (C) | May Birthday? |
|---|---|---|---|
| Aria Chen | 1989-05-14 | 5 | Yes (#1) |
| Liam Patel | 1994-11-03 | 11 | No |
| Noah Silva | 1978-05-29 | 5 | Yes (#2) |
| Sofia Rossi | 2001-05-02 | 5 | Yes (#3 — 3 in May) |
Year-independent monthly count and roster list formulas
Match target month integer E2 (5 = May) against the extracted MONTH column C2:C5.
=COUNTIF(C2:C5, E2)List all employees celebrating a birthday in target month E2
Combines FILTER and TEXTJOIN with a clean "None" fallback.
=TEXTJOIN(", ", TRUE, FILTER(A2:A5, C2:C5 = E2, "None"))Inputs and interpretation
Use valid numeric date values and a target month from 1 through 12. Missing dates must not become January through zero coercion. This groups calendar months across years, not a single chronological month. If extending it to seasonal sales, unequal year coverage and changing business size affect comparisons.
Try the example
Use the original values or change them to test your understanding.