Weeks between two dates
This tool counts how many weeks separate any two dates, reporting the span three ways: as full weeks plus leftover days, as an exact decimal-week figure, and as a total day count. It is handy for pregnancy tracking, project timelines, notice periods, leave calculations, and counting down to a deadline.
How it works
Both dates are floored to local midnight, so the result never wobbles with the time of day. The tool then takes the absolute difference in days and divides by 7:
total days ÷ 7 = decimal weeks
The whole-number part is the count of full weeks, and the remainder is the leftover days. Because it uses the absolute difference, the order you enter the dates in does not matter — the answer is always positive. Leap years are handled automatically — any February 29 that falls within the range is counted as a normal day.
Worked example
From 1 January 2026 to 15 February 2026 is 45 days. Dividing by 7 gives 6 weeks and 3 days (6 × 7 = 42, with 3 days left over), or 6.43 weeks as a decimal.
Common use cases and what to enter
Pregnancy tracking: Enter the first day of the last menstrual period (LMP) as the start date and today as the end date. The result shows the current gestational week, which matches the week number used in prenatal appointments. A full-term pregnancy is 40 weeks (280 days) from LMP.
Notice periods: Employment contracts often specify weeks of notice. Enter the notice-start date and the proposed last day to verify the period meets the contract requirement.
Project sprint planning: Sprints are typically two-week cycles. Enter the project start and deadline to see how many full sprints fit, with any leftover days visible as the partial sprint.
Leave and holiday calculations: HR teams use week counts to validate annual leave bookings that span part-weeks. The “full weeks plus days” format matches most leave-policy language.
Counting down to an event: Enter today and the event date to see both the full weeks remaining and the exact decimal figure for planning progress milestones.
The three output formats explained
| Format | Example | When to use it |
|---|---|---|
| Full weeks + days | 6 weeks 3 days | Human-readable, matches contract/policy language |
| Decimal weeks | 6.43 weeks | Calculations, progress percentages, charting |
| Total days | 45 days | The underlying figure; useful for verifying manually |
All three derive from the same day count — they are different ways of presenting the same measurement. Both dates stay in your browser and are never sent anywhere.