Quick answer
Define the interval once as a rule, generate the concrete dates from it, then apply holidays and closures as visible adjustments.
Rules generate dates; dates do not generate rules
A weekly seminar, a fortnightly review, a monthly assessment — each is a rule with a start date and an interval. Typing out the resulting dates by hand works once and then decays: a term shifts, a room changes, someone edits one date and not the others, and by mid-term two versions of the schedule are circulating.
Keeping the rule as the source of truth means a change is made in one place. Regenerate the dates, republish, and the whole sequence stays consistent. This is also what makes the schedule auditable — anyone can check whether a date belongs to the sequence.
Use this guide with the right tool: Open the Term Date Planner for the next scheduled date in a repeating academic or term calendar. If the question shifts, compare it with the Semester Length Calculator or the Recurring Date Calculator.
Weekly intervals are stable; monthly ones are not
A weekly or fortnightly interval always lands on the same weekday, which makes it easy to reason about and easy to fit into a timetable. A monthly interval keeps the day number and therefore moves across weekdays, which is usually not what an academic schedule wants.
If a monthly rhythm is genuinely needed, consider expressing it as "every fourth week" instead. That keeps the weekday fixed and gives thirteen occurrences a year rather than twelve — close enough for most purposes and far easier to timetable.
Holidays and closures are exceptions, not part of the rule
Term breaks, public holidays, reading weeks and institutional closures interrupt a sequence without changing its underlying rule. Model them that way: generate the full sequence, then mark the interrupted occurrences and decide individually whether each is cancelled or moved.
Building the exceptions into the interval itself is what produces schedules nobody can maintain. Once an exception is baked in, the rule no longer describes the sequence, and the next person to edit it has to reverse-engineer the intent.
Publishing dates people can act on
A published schedule should carry the weekday alongside the date. "Week 6 — Tuesday 22 September" is checkable at a glance; "Week 6" is not, and week numbering conventions differ between institutions and from ISO numbering.
Where the schedule spans a year boundary, include the year on every date. Academic years cross into January, and a bare day-and-month in a term list is exactly the kind of detail that gets misread by one year.
Worked example
Starting Tuesday 15 September 2026 and repeating every two weeks gives 29 September, 13 October and 27 October, with the reading week session marked as an exception. Build your start date and interval, then list exceptions instead of shifting sessions.
The worked example, run to the end of term
Generate the worked example's seminar in full. A fortnightly Tuesday seminar starting 15 September 2026 produces 29 September, 13 October, 27 October, 10 November, 24 November and 8 December — seven occurrences spanning exactly 84 days, twelve weeks, from first to last. The reading week takes out 27 October, as the worked example says: marked as an exception, the sequence around it is untouched, and six sessions are delivered by the end of term. Run the rule one step further and it produces Tuesday 22 December, deep in the Christmas closure at most institutions — a second exception of a different kind, since it was predictable from the calendar rather than from the term's own rhythm — and then Tuesday 5 January 2027, the year included, because a schedule that crosses into January without years on its dates is inviting a one-year misreading.
The alternative to cancelling the reading-week session shows why the exception model matters. Move 27 October to Tuesday 3 November and the term delivers all seven sessions — but 3 November and 10 November now sit seven days apart inside a fortnightly rhythm, a local irregularity every attendee has to be told about, while the rule itself and every later date stay clean. Cancel, and the irregularity is an absence; move, and it is a crowding. Either is defensible. What is not defensible is the third option, shifting everything after 27 October by a week: the rule stops describing the schedule, and the next editor inherits a list of dates with no way to regenerate them.
Set the monthly alternative beside it, using the same start. A seminar fixed to the 15th of each month meets on Tuesday 15 September 2026, Thursday 15 October, Sunday 15 November and Tuesday 15 December. The third of those is a Sunday — the monthly rule has generated a session no timetable can hold, and it did so within three steps. The four-weekly version of the same seminar meets on 13 October, 10 November and 8 December, all Tuesdays, and never leaves the weekday at all.
Number the weeks the way an institution would, and the sequence becomes publishable in the checkable form the earlier section asks for. The sessions fall in term weeks 1, 3, 5, 7, 9, 11 and 13: "Week 1 — Tuesday 15 September 2026", "Week 5 — Tuesday 13 October", and so on, with Week 7 published as "no session — reading week" rather than silently skipped. The numbering itself becomes a diagnostic. If a date in the published list ever appears against the wrong week number, one of them is wrong in a way a reader can spot at a glance, because the rule, the week count and the weekday all have to agree — and any reader can regenerate the whole list from the start date and the interval to check.
Common mistakes to avoid
- Typing out the sequence by hand. It decays the first time something changes. Keep the rule and regenerate.
- Using a monthly interval for a timetabled session. Monthly intervals move across weekdays. Use a four-week interval to keep the day fixed.
- Building holidays into the interval. Model them as exceptions to a clean rule, or the schedule becomes unmaintainable.
Use the right calculator
Use the Term Date Planner for the next date in a repeating term calendar, the Semester Length Calculator for term length, and the Recurring Date Calculator for repeating schedules.
Frequently asked questions
How do I handle a session that falls on a holiday?
Mark it as an exception and decide whether to cancel or move it. Do not shift the whole sequence.
Should term weeks use ISO week numbers?
Only if your institution does. Institutional week numbering usually starts at term start, which is not the same as ISO numbering.
How far ahead should a schedule be generated?
Far enough to be useful and close enough to be accurate — usually one term or semester at a time.