Recurring Event Calculator
Generate recurring event dates from a start date and interval.
Overview
The Recurring Event Calculator generates a list of upcoming event dates from a start date and a recurrence rule. Choose a starting moment, pick a frequency (daily, weekly, monthly, yearly) and interval, set how many occurrences to generate, and the tool lists every fire date along with its weekday.
Useful for project managers laying out sprint kickoffs, accounting teams scheduling recurring invoices, anyone planning a "first Tuesday of every month" club meeting, gym-routine builders, and developers prototyping a calendar feature before wiring it into a full RFC 5545 RRULE engine.
How it works
The expansion follows the same semantics as RFC 5545 RRULE: each subsequent occurrence is computed by adding the interval × frequency unit to the previous one, with month and year additions clamping to the last valid day of the target month when necessary. Daily and weekly intervals are simple multiples of 24 hours and 7 days respectively, so they are unaffected by month length.
When monthly rules land on a day that does not exist in a target month (Jan 31 + 1 month), the result clamps to Feb 28 or 29 — matching the ISO 8601 calendar arithmetic and the RFC 5545 "MONTHLY by absolute date" behaviour. For "first Monday of each month" style rules, the calendar week grid plus the working-days calculator are better suited.
Examples
Start 2026-05-18, daily, 10 occurrences
→ 2026-05-18 .. 2026-05-27
Start 2026-05-18 (Monday), weekly, every 2 weeks, 5 occurrences
→ 2026-05-18, 2026-06-01, 2026-06-15, 2026-06-29, 2026-07-13
Start 2026-01-31, monthly, 6 occurrences
→ 2026-01-31, 2026-02-28, 2026-03-31, 2026-04-30, 2026-05-31, 2026-06-30
Start 2024-02-29, yearly, 5 occurrences
→ 2024-02-29, 2025-02-28, 2026-02-28, 2027-02-28, 2028-02-29
FAQ
How are end-of-month dates handled?
The result clamps to the last day of the target month, matching RFC 5545 monthly recurrence and .NET DateTime.AddMonths. A Jan 31 monthly rule lands on Feb 28, Mar 31, Apr 30, and so on.
How does it handle Feb 29?
A yearly rule starting Feb 29 lands on Feb 28 in non-leap years and back on Feb 29 in leap years — the conservative interpretation also used by most calendar apps.
Can I exclude weekends?
This tool generates raw calendar occurrences. For business-day-only output, post-filter with the working-days calculator or use an RRULE with BYDAY=MO,TU,WE,TH,FR through the iCal RRULE builder.
What is the maximum number of occurrences?
The tool generates up to 1,000 occurrences in a single run. For longer series, generate in chunks or fall back to a full iCalendar implementation.
Does it honour holidays?
No — holiday awareness is country-specific and outside the scope of a plain recurrence rule. Combine with the working-days calculator's holiday list if you need it.