Weeks Between Dates Calculator
Calculate the exact number of weeks between any two dates. Whole weeks plus partial week, or decimal weeks for tracking purposes.
Weeks between two dates is the simplest of all date-difference questions because a week is always 7 days. Take the total day count and divide by 7.
Example: January 1 to December 31, 2024
2024 was a leap year with 366 days. 366 / 7 = 52.286 weeks. Or 52 weeks and 2 days.
Common Week-Counting Use Cases
| Scenario | Why it matters |
|---|---|
| Pregnancy tracking | 40-week gestational standard; trimesters defined by week count |
| Project deadlines | Sprints, milestones, vacation countdowns |
| Unemployment benefits | Eligibility windows measured in weeks of work |
| Subscription length | Weekly billing periods, free-trial countdowns |
| Marathon training | Programs structured as 12-, 16-, or 20-week blocks |
ISO Week Numbers
The international standard defines week 1 as the first week containing a Thursday. A year always has 52 or 53 ISO weeks. Europeans use ISO weeks for scheduling and reporting more commonly than Americans, who tend to use month-based reporting. The date difference calculator uses simple 7-day weeks; for ISO week numbers, see the ISO 8601 specification.
Use the Full Calculator
The Date Difference Calculator handles every scenario described on this page. For the deeper math and worked examples, read the companion guide.