How the weeks are counted
The number of weeks is the number of days divided by 7. 100 days is 14 weeks and 2 days, or 14.29 weeks. The tool shows both forms, and also the number of calendar weeks that the period touches, which is higher because a period usually starts and ends in the middle of a week.
Week table
The table lists each calendar week in the period, with its first and last day, and how many days of your period fall in it. Choose whether weeks start on Monday or on Sunday. With Monday, the table also shows ISO week numbers.
ISO week numbers
ISO 8601 weeks start on Monday, and week 1 of a year is the week that contains the first Thursday, which is also the week with 4 January. A year has 52 or 53 ISO weeks. The first days of January can belong to the last week of the previous year, and the last days of December to week 1 of the next year.
Weeks and days
| Weeks | Days |
|---|---|
| 4 | 28 |
| 12 | 84 |
| 26 | 182 |
| 52 | 364 |
A common year is 52 weeks and 1 day, and a leap year is 52 weeks and 2 days.
Include the end date
Tick Include the end date to count both the first and the last day in the total. The table always counts both days.
Uses
- Project plans and sprints.
- Pay periods and schedules that repeat every week or every two weeks.
- School terms, courses and training plans.
Related calculators
See days between dates for the day count, months between dates, working days and date difference. The guide has formulas for sheets and code.