Semester weeks calculator
Enter the first and last day of a semester or term and this tool counts how many weeks it runs — full weeks plus any extra days, and a decimal weeks figure — counting both endpoints inclusively. It is built for students and teachers planning a syllabus, timetable or revision schedule around the length of a term.
How it works
The tool measures the gap between the two dates in whole days and adds one, so both the first and last day are counted (an inclusive count). It then splits that into weeks:
total days = (end − start) ÷ 1 day + 1 full weeks = floor(total days ÷ 7) extra days = total days mod 7 decimal weeks = total days ÷ 7
It also reports which weekday the term begins and ends on.
Example
A term running Monday 8 September to Friday 12 December:
| Figure | Value |
|---|---|
| Total days (inclusive) | 96 |
| Full weeks | 13 |
| Extra days | 5 |
| Decimal weeks | 13.7 |
So the semester is 13 weeks and 5 days long. Everything runs in your browser, with nothing uploaded.
How long is a typical semester?
Term lengths vary widely by country and institution type:
- University semesters (US) — most run roughly 16 weeks from the first day of classes to the last day of final exams. A semester with classes ending in week 14–15 and exams in weeks 15–16 is common.
- University terms (UK) — the three-term year has shorter terms, typically around 10–11 weeks each, although the academic year can be up to 30 weeks of teaching in total.
- Quarter systems — approximately 10 weeks of instruction plus an exam week, making a four-quarter year.
- Secondary schools — terms vary from roughly 6 to 14 weeks depending on the country and whether half-term breaks are counted in or out.
Enter your actual dates to get the precise figure rather than relying on these general ranges.
Planning your syllabus or revision schedule
Once you know the week count, a few useful splits:
- Teaching vs. reading weeks — if your institution has a mid-semester reading week, subtract one from the teaching weeks.
- Assignment spacing — for a 12-week teaching semester, spacing major assignments every 3–4 weeks is common.
- Exam countdown — knowing you have 13 weeks and your exam is in week 12 lets you plan backwards: week 12 revision, weeks 9–11 consolidation, weeks 1–8 new material.
- Lecture planning — two lectures per week over 12 teaching weeks equals 24 lectures, enough to plan a topic list without overcounting.
The decimal week figure is useful for proportional planning — for example, if you want to cover the first third of your syllabus by week 4 of a 13.7-week term, that is roughly the 29% mark.