Weeks Between Dates Calculator
Count the weeks and days between two dates.
Results update as you type.
How it works
A weeks between dates calculator tells you how many full weeks separate two dates, how many leftover days remain beyond those whole weeks, and the total number of days for reference. It answers everyday planning questions like "how many weeks until the deadline" or "how many weeks was I away," breaking a span down into the units people actually schedule in. Weeks are a natural planning currency: pregnancies, sprints, notice periods, training programmes and countdowns are all commonly counted in weeks rather than raw days. Converting a day count into weeks plus a remainder is more useful than either alone, because "seven weeks and three days" is easier to reason about than "52 days." Doing it by hand means dividing by seven and tracking the remainder, which is where small mistakes creep in, especially across month and year boundaries. The calculation is exact because it works from a continuous day count on the UTC calendar, so every leap day inside the span is already included before dividing by seven. The full-weeks figure uses floor division, and the extra days are the remainder, so the two always reconstruct the total. Project managers tracking timelines, expectant parents counting gestational weeks, and anyone measuring a stretch of time use a weeks between dates calculator to turn two dates into weeks and days at a glance.
totalDays = endDate − startDate; weeks = ⌊totalDays ÷ 7⌋; extraDays = totalDays mod 7
The two dates are converted to a continuous count of whole days, and the end count minus the start count gives the total days between them. Dividing that total by seven with floor division yields the number of complete weeks, and the remainder after removing those weeks is the leftover days, always between zero and six. Because the day total is taken from a UTC day index, every leap day within the range is counted automatically, so the weeks-and-days breakdown is exact.
Source:Gregorian calendar / ISO 8601
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter start date and end date.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Full weeks updates instantly as you type — no button to press.
Frequently asked questions
How many weeks are between two dates?
Take the total number of days between the dates and divide by seven; the whole-number part is the full weeks and the remainder is the leftover days. This calculator does both, so 17 days becomes 2 weeks and 3 days. Counting complete weeks this way is more meaningful for planning than a raw day figure, and the leftover days tell you exactly how far into the next week the end date falls.
Does it count the start or end date?
It measures the gap between the two dates, so the start date is day zero and the end date is counted, giving the number of days from one to the other. If you need to include both endpoints, for example counting inclusive days in a booking, add one to the total-days figure before converting to weeks. Whether to count inclusively depends on what you are measuring, so the tool reports the plain gap.
Why show extra days as well as weeks?
Because most real spans are not an exact multiple of seven days, the remainder matters. Reporting only whole weeks would hide up to six days, which can be the difference between meeting and missing a deadline. Showing weeks plus extra days lets you state a duration precisely, such as a notice period of "six weeks and two days," while still giving the total days for any calculation that needs the raw count.
Is it accurate across leap years?
Yes. The total-days figure is taken from a continuous day count that already includes any 29 February falling between the two dates, so the week count is correct even when the span crosses a leap day. There is no separate adjustment to make. This is why computing from a day index is more reliable than trying to count weeks month by month, where a leap day is easy to overlook.
How do I count pregnancy or gestational weeks?
Enter the start date, typically the first day of the last menstrual period, and the current or due date, and read the full weeks and extra days. Gestational age is conventionally stated as completed weeks plus days, exactly the form this calculator returns, so 30 weeks and 4 days reads directly. For medical decisions always confirm with a clinician, as due dates are estimates and dating methods vary.