How to Calculate Weeks Between Dates: A Step-by-Step Guide
Counts weeks between two dates.
Dates and durations matter for notice periods, leave planning, project deadlines and contracts. Counting days on a calendar is slow and easy to get wrong, especially across months of different lengths.
What you need
- Start date
- End date
Step by step
- Enter the start date.
- Enter the end date.
- The results update as you type, or press Calculate.
- Read the weeks first, then the supporting figures below it.
The formula
Weeks = days ÷ 7.
Worked example
For example, with these inputs:
- Start date: 5 Jan 2026
- End date: 5 Oct 2026
the calculator returns:
- Weeks: 39.00 weeks
- Full weeks: 39 weeks
Practical tips
- Public holidays are not weekends; subtract them separately when counting working days.
- Convert times to minutes before subtracting, then convert back to hours and minutes.
- Months have different lengths, so 'one month' is not always 30 days.
- Decide upfront whether the end date should be counted, because it changes the answer by one day.
Background
The Gregorian calendar has months of 28 to 31 days and adds a leap day almost every four years, which makes counting days by hand surprisingly error-prone. Converting dates to day numbers and subtracting avoids the problem.
Age is calculated in completed years, months and days. Someone born on 29 February is usually treated as turning a year older on 28 February or 1 March in non-leap years, depending on the rule being applied.
When sharing dates internationally, write the month as a word to avoid confusion between day-month and month-day formats.
Related calculations
- Working Days Calculator: Counts weekdays between two dates, inclusive.
- Day of the Week Calculator: Tells you which weekday any date falls on.
- Months Between Dates Calculator: Counts complete calendar months between two dates.
- Time Duration Calculator: Calculates hours and minutes between two times, including overnight shifts.
Want to skip the arithmetic? The free Weeks Between Dates Calculator does all of this instantly and updates as you type.
Run your own numbers: Weeks Between Dates Calculator