To calculate the number of weeks between two dates, first find the total elapsed days. Divide that number by seven. The whole-number quotient is the number of complete weeks, while the remainder is the number of additional days.
Enter two dates to calculate exact years, months, weeks, days, weekdays, weekends, and inclusive date counts.
Divide the total day interval by seven and keep any remainder as additional days.
Weeks Between Dates Formula
Find the total elapsed day difference before converting it into weeks.
Divide the total days by seven because every week contains seven calendar days.
The Date Difference Calculator reports complete weeks and remaining days automatically.
Worked Example: Seventeen Days
Suppose two dates are 17 elapsed days apart.
Seventeen divided by seven gives two complete weeks with a remainder of three.
The interval is therefore two weeks and three days.
How to Find the Remaining Days
Multiply the number of complete weeks by seven.
Subtract that amount from the total elapsed days.
For 17 days, two weeks account for 14 days, leaving three.
Exact Weeks vs Decimal Weeks
A calendar interval can be expressed as complete weeks plus days or as a decimal number of weeks.
Seventeen days equals two weeks and three days.
It also equals approximately 2.43 weeks because 17 divided by seven is approximately 2.4286.
| Format | Result for 17 days | Best use |
|---|---|---|
| Weeks and days | 2 weeks, 3 days | Calendar schedules |
| Decimal weeks | Approximately 2.43 weeks | Rates and calculations |
Worked Example with an Exact Number of Weeks
Suppose the dates are 28 elapsed days apart.
Dividing 28 by seven gives exactly four.
The result is four complete weeks with no remaining days.
Weeks Between January 1 and January 10
January 1 to January 10 is nine elapsed days.
Nine divided by seven gives one complete week with two days remaining.
The result is one week and two days.
Inclusive Weeks and Days
An inclusive count adds one day before converting the interval into weeks.
January 1 through January 10 contains ten inclusive days.
Ten days equals one complete week and three remaining days.
Calendar Weeks vs Complete Seven-Day Periods
A complete week in a duration calculation means any uninterrupted seven-day period.
It does not need to begin on Monday or Sunday.
A calendar week, by contrast, may refer to a named week in a calendar system.
Do Weekends Affect the Week Count?
No. Every complete calendar week contains seven days, including Saturday and Sunday.
Weekends matter only when calculating weekdays or business days.
Ordinary week conversion uses the full calendar-day difference.
Leap Years and Week Calculations
A leap day adds one day to an interval crossing February 29.
That extra day may change the remainder or produce an additional complete week in a long interval.
The day difference should therefore be calculated from the actual calendar dates first.
How to Calculate the Total Days First
Subtract the earlier date from the later date.
Use an exclusive or inclusive day count according to the purpose.
Read How Many Days Are Between Two Dates? for the day-counting method.
Common Mistakes
Do not divide month numbers or date numbers directly by seven.
Do not discard the remainder when the interval is not an exact multiple of seven.
Do not add one day unless inclusive counting is required.
Do not exclude weekends from an ordinary calendar-week calculation.
Conclusion
Find the elapsed day difference and divide it by seven.
Use the whole-number result as complete weeks and keep the remainder as additional days.
Use the Date Difference Calculator to calculate both values instantly.
FAQs
How do I calculate weeks between two dates?
Find the elapsed days and divide that number by seven.
How many weeks are 17 days?
Seventeen days equals two complete weeks and three days.
How many weeks are nine days?
Nine days equals one complete week and two days.
Are weekends included?
Yes. Ordinary calendar weeks include all seven days.
Can I express the result as a decimal?
Yes. Divide the total day count by seven without discarding the decimal.