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Calendars overview

PostRoll worlds use a calendar to show dates — but you don’t have to define one. Every world starts with a built-in Gregorian fallback, so you can record events the second you create a world and never think about calendars again.

When you do want fantasy calendars, the same workspace handles custom months / weekdays / eras / intercalary days / leap rules, and you can have any number of them per world.

When the Gregorian fallback is enough

Section titled “When the Gregorian fallback is enough”

If your campaign is in the real world (modern fiction, urban fantasy, historical settings) — done. The fallback handles dates from BC to the far future, with the standard 4/100/400 leap cycle.

The fallback also works fine for session-only campaigns where you don’t care about in-world dates at all. Use session precision on every event; the calendar is irrelevant.

When you want a custom calendar

Section titled “When you want a custom calendar”

Reach for a custom calendar when:

  • The setting has named months that aren’t January/February (Brightember, Hammer, Solace).
  • The setting has non-7-day weeks (Harptos has a 10-day “tenday”).
  • Years count differently — eras like DR, SR, PD, or regnal “Year 12 of the Reign of Mira”.
  • There are feast days outside the normal week that always fall on a specific date (Midwinter, Shieldmeet, Highharvestide).
  • You want events to display “12 Brightember 1247 SR” instead of “April 4, 2026 CE”.

You can have multiple calendars per world — for example, an in-world Harptos calendar marked primary plus a real-world Gregorian for session scheduling. Events display correctly in either. See Multiple calendars.

What the primary calendar drives

Section titled “What the primary calendar drives”

Marking a calendar as primary affects:

  • The Timeline tab — era bands at the top use this calendar’s eras.
  • The Calendar tab — Year and Month views default to this calendar.
  • The Cycles tab — date scrubber resolves “Go to” inputs against this calendar’s months and eras.
  • The smart When field — 1247 SR resolves the era short label against the primary calendar’s eras.
  • The Markdown export — dates appear in the primary calendar’s format.
  • The Chronicle and Agenda tabs — group headings and date display.

Switching the primary calendar updates all of these. Existing events keep their authored dates (they don’t get rewritten); only display shifts.

What each event records

Section titled “What each event records”

When you author an event with a custom calendar:

  • The event remembers which calendar you used, plus the year, month, day, and era you entered.
  • It also records its universal master timeline position — a single sortable axis every view uses, no matter which calendar authored the event.

Keeping both is what lets you switch the display calendar in the Calendar tab and see the same events at the equivalent date in the chosen calendar — see Multiple calendars.

Templates

Section titled “Templates”

The Settings → Calendars + New dialog clones from one of five starter templates:

  • Gregorian — the real-world calendar, anchored to 1970.
  • Harptos — Forgotten Realms (12 × 30 days, 10-day week, 5 feasts + Shieldmeet).
  • Four Seasons — four ~91-day periods, no weekdays.
  • Campaign Days — one numbered day per campaign day.
  • Blank — empty, configure everything yourself.

After cloning you can edit every field — months, weekdays, eras, intercalary days, leap rules, display format. See Building a calendar.

Section titled “Related”