Worked example: the back-to-school countdown
For most kids the Halloween wait starts when school does. From September 1 to October 31 is 60 days exactly — September's 30 days plus October's 31, minus the day you started on. That is 8 weeks and 4 days of costume planning. If you start on October 1 instead, the wait is a neat 30 days, and from Friday the 13th of October (in years that have one) it is 18.
Why October 31?
The name is the calendar: "Halloween" is a contraction of All Hallows' Eve, the night before All Hallows' Day — better known as All Saints' Day, fixed on November 1 in the Western church. That makes Halloween a date-locked eve, like Christmas Eve or New Year's Eve, which is why it never moves. Its older roots are usually traced to Samhain, the Gaelic festival marking the end of the harvest and the start of winter, observed around the same turn of the calendar. And in Mexico the same stretch of days belongs to Día de los Muertos, celebrated over November 1–2.
A number joke worth retelling
Programmers like to say OCT 31 = DEC 25. It is not about holidays at all: 31 in octal (base 8) is 3 × 8 + 1 = 25 in decimal (base 10). Halloween equals Christmas — provably. It is also a handy mnemonic for the real calendar fact that the two holidays sit exactly 55 days apart, every year, because no leap day can fall between them.
What follows Halloween
| Observance | Date | Distance from Halloween |
|---|---|---|
| Halloween (All Hallows’ Eve) | October 31 | — |
| All Saints’ Day (All Hallows’ Day) | November 1 | 1 day after |
| All Souls’ Day | November 2 | 2 days after |
| Día de los Muertos (Mexico) | November 1–2 | 1–2 days after |
| Bonfire Night (UK) | November 5 | 5 days after |
| US Thanksgiving (4th Thursday of Nov) | November 22–28 | 22–28 days after |
| Christmas Day | December 25 | 55 days after |
Thanksgiving's distance is a range because it floats with the weekday calendar — the fourth Thursday of November lands anywhere from the 22nd to the 28th. Everything else in the table is date-locked.
Related countdowns
Halloween opens the holiday run: next comes days until Thanksgiving, then days until Christmas — always 55 days out from here — and days until New Year at 62. Counting to something else entirely? The days until calculator takes any date, past or future.