Everyday math
Count the calendar days between two dates.
Enter your numbers to see the answer.
Date difference calculator guide
A date difference calculator counts the calendar time between a start date and an end date. It is useful for project schedules, deadlines, subscriptions, age checks, travel planning, and understanding how many days remain between two dates. The key choice is whether the count is exclusive or inclusive: the difference from August 1 to August 31 is 30 elapsed days when the start is not counted, but 31 calendar dates when both endpoints are included. This page shows the elapsed days as the headline, the same span in weeks, and the inclusive count on a separate row so you can match the result to the question you are asking. The arithmetic uses real month lengths and leap days, and it treats both inputs as whole calendar dates rather than times of day.
Elapsed days = end date − start date, rounded to whole days. Weeks = elapsed days ÷ 7. Inclusive calendar days = elapsed days + 1 when both the start and end dates are counted.
Worked example with the default dates: from August 1, 2026 to August 31, 2026 the calculator subtracts the two dates and displays 30 days. The weeks row divides by seven: 30 ÷ 7 = 4.3 weeks. The inclusive row adds one so both endpoint dates count: 30 + 1 = 31 days, which is the full length of August. Swapping to a start of January 1 and end of December 31 in the same year would give 364 elapsed days and 365 inclusive days, or 366 inclusive in a leap year such as 2028.
The inputs are calendar dates, not times of day, so a span from 9 a.m. to 5 p.m. on the same date is 0 days. Decide whether you need elapsed days, inclusive days, or working days; weekends and holidays are not removed by this calculator. If the end date is earlier than the start date the result is clamped to 0 rather than shown as a negative number.
Use elapsed days for durations and inclusive days for date lists, coverage periods, or tasks where both endpoint dates count. For business schedules, use the working-days calculator instead.
Do not count the starting date twice: a rental from the 1st to the 31st that is billed “per night” has 30 billable nights, while a contract covering the 1st through the 31st inclusive spans 31 days. Do not assume every month has 30 days when checking the result by hand, and do not use calendar days when a contract, court, or payroll rule specifies weekdays or business days. Check the year on both inputs; a typo that shifts one date by a year adds 365 or 366 days silently.
Date calculations depend on the endpoint convention. Write the rule in words before relying on the result for a deadline, contract, billing period, or age calculation.
How it works
Count the calendar days between two dates. This tool explains the calculation so you can adjust the assumptions to match your situation.
Worked example
With Start date = 2026-08-01 · End date = 2026-08-31 → 30 days (calendar days between dates). Change an input above and this example updates with your numbers.
Common questions
Enter the start and end dates to see the elapsed calendar days, the equivalent weeks, and the inclusive count. With the default August 1 to August 31, 2026 the elapsed result is 30 days and the inclusive result is 31.
Add one to the elapsed-day difference. For August 1 through August 31, 2026, that produces 31 inclusive calendar days, which is the figure to use for coverage periods, rentals billed per day, or any list that includes both endpoints.
No. It counts calendar dates and ignores weekends and public holidays. Use the working-days calculator when weekends or holidays must be excluded, for example for court deadlines or delivery promises.
Yes. Calendar arithmetic accounts for the actual month lengths and leap days represented by the dates you enter, so February 28 to March 1 is 1 day in 2027 and 2 days in 2028.
The most common cause is whether the start date, end date, or both endpoints are included. Check the counting convention before comparing results; an inclusive count is always exactly one day more than the elapsed count.