Repeating Date Pattern Calculator
Find recurring dates based on a repeating pattern.
How recurrence rules generate dates
The calculator supports two main recurrence patterns: fixed day-of-month rules like 'the 15th of every month' and nth-weekday rules like 'the second Tuesday of every month'. Fixed-day rules are the simpler case — they advance one month at a time and emit the same day number. Nth-weekday rules are more flexible because they anchor to the weekday rather than the date, which keeps events like board meetings and paydays from drifting onto weekends. To compute the second Tuesday of a month, the algorithm finds the first Tuesday on or after the 1st and adds seven days.
Edge cases appear when a month cannot satisfy the rule. A fixed-day rule of 'the 31st' skips February, April, June, September, and November because those months have no 31st. Similarly, an nth-weekday rule like 'the fifth Friday' applies only to months whose weekday arrangement includes a fifth Friday — roughly four or five months per year. Rather than silently producing wrong dates, the calculator simply omits months that cannot fulfill the rule, which matches how most payroll systems, court calendars, and subscription billing engines handle these cases.
Common recurring-date use cases
Meetings, paychecks, and bill due dates are the most obvious uses. A payroll calendar that runs on the 15th and the last day of every month requires exactly this kind of generator, and the calculator can preview the next ten or fifty occurrences so HR and finance teams can confirm the schedule is correct before committing it to a payroll system. Board meetings often land on the third Thursday or second Tuesday of each month so members can plan travel a year in advance. Medication schedules, rent payments, and loan installments share the same structure.
Less obvious but equally common uses include parenting-time schedules in custody agreements ('first and third weekends'), cleaning services ('every other Wednesday'), and academic deadlines ('the Friday of each even ISO week'). Previewing a long sequence helps identify overlaps with holidays — if the third Monday of February is Presidents Day, a recurring team standup on that date will collide every year and may need a one-time skip. By showing the next 10 or 50 dates at once, the calculator makes these conflicts visible before they become scheduling problems, letting you adjust the rule or add exceptions proactively.