How recurring calendar events work

What Are Recurring Events?

Recurring events are calendar events that repeat according to a defined pattern. Instead of creating individual events for every weekly meeting or monthly review, calendar apps create one event with a recurrence rule (RRULE) that describes when the event repeats.

The RRULE Specification

Recurring events use the RRULE format defined in RFC 5545 (iCalendar specification). This standard allows complex recurrence patterns while keeping the calendar file size small.

Common RRULE Components

FREQ (Frequency)

Defines how often the event repeats:

• FREQ=DAILY - Every day
• FREQ=WEEKLY - Every week
• FREQ=MONTHLY - Every month
• FREQ=YEARLY - Every year

INTERVAL

Specifies the interval between occurrences:

• INTERVAL=1 - Every period (default)
• INTERVAL=2 - Every other period (bi-weekly, bi-monthly, etc.)

COUNT or UNTIL

Limits the number of occurrences:

• COUNT=10 - Repeat exactly 10 times
• UNTIL=20241231T235959Z - Repeat until this date

BYDAY

Specifies which days of the week:

• BYDAY=MO - Mondays only
• BYDAY=MO,WE,FR - Monday, Wednesday, Friday
• BYDAY=2TU - Second Tuesday of each month

Example RRULEs

How the ICS Tool Handles Recurring Events

When you use the ICS to Excel tool with a date range:

1. The tool reads the RRULE from the event
2. It calculates all occurrences within your specified date range
3. Each occurrence becomes a separate row in the output
4. Original event details (title, location, description) are copied to each row

Exceptions and Modifications

Calendar apps handle exceptions to recurring events:

• EXDATE: Specific dates when the event doesn't occur
• Modified instances: Individual occurrences with changed details
• This and future: Changes applied to one occurrence and all future ones

Best Practices

• Use end dates: Always set an end date or count limit to prevent infinite recurrences
• Consider time zones: Recurring events can behave unexpectedly across daylight saving time changes
• Test your rules: Verify recurrence patterns in your calendar app before relying on them

Related Tools

• ICS to Excel - Convert calendar files with recurring event expansion

FAQ

Q: Why does my weekly event show wrong dates after conversion?
A: Check your date range selection. The tool only expands events within the specified range.

Q: Can I edit individual occurrences?
A: The ICS tool exports all occurrences as separate rows. You can edit them in Excel, but this won't update your original calendar.

Q: What about all-day recurring events?
A: The tool handles all-day events correctly, showing them without specific times in the output.