Calculating the weeks between two dates can be confusing if the two dates are far apart. You can do it manually, but there are many websites that allow you to enter two dates and will perform the calculations for you for free. Many of these sites also include additional information such as number of days, hours and minutes.
Free Online Date Calculators
Navigate to a date calculator in your web browser (see Resources).
Enter the starting date in the top set of boxes on in the calculator. This may be entered by selecting the date from a series of drop-down menus, entering each field individually (month, day, year) or by entering the entire date in “mm/dd/yyyy” format.
Enter the end date in the bottom set of boxes, using the same format as the start date.
Click “Calculate” to view the results. If only days are shown, divide the number of days by 7 to complete the week calculation. For instance, 700 days divided by 7 equals 100 weeks.
Calculate the number of years elapsed between the two dates by subtracting only the complete years falling within the date range. For instance, if calculating the number of weeks between Aug. 13, 1991 and June 15, 2010, subtract 2009 from 1991, as the June end date falls short of a whole year. In this case there are 18 complete years between the two dates.
Multiply the number of complete years by 365 to convert the complete years into days, not accounting for leap years. In this conversion there are 18 complete years, or 6,570 days. Write this number down.
Using the Day of Year Calendar provided in the Resources section, identify the exact day of the year for each date. The year is not used in this step. For example, Aug. 13 is the 225th day of the year and June 15 is the 166th day of the year, again not accounting for leap years.
Subtract the end date day of the year from the start date day of the year to reveal the short-term day difference. In this case, June 15, 2010, which is the 166th day of the year, is the end date. Aug. 13, 1991, which is the 225th day of the year, is the start date. Subtracting 166 from 225 results in minus 59, a negative number. If the number is not negative, proceed to the next step. If the number is negative, add 365 to the negative number. In this case, 365 will be added to minus 59, the result of which is 306. Write this number down.
Determine the number of leap years occurring between the two dates using the List of Leap Years provided in the Resources section. In this case, there are five leap years between the two dates, occurring in 1992,1996, 2000, 2004 and 2008.
Add all three numbers together to determine the total number of days between the two dates. In this example, add the number of days elapsed between the two dates (6,570), the short-term day difference (306) and the number of leap years (5) for a total of 6,881 days between the two dates.
Divide the total number of days between the two dates by 7 to determine the number of weeks. In this example, there are 983 weeks between Aug. 13, 1991, and June 15, 2010.