How Many Days Between Two Dates? (With Formula & Examples)
Automated technical check: . Scope and review policy
A date difference counts calendar boundaries between two dates. It is not always the same as dividing elapsed hours by 24: daylight-saving changes can make a local day shorter or longer. The Date Difference Calculator uses calendar dates, so a change of device time zone does not change the answer.
A worked example
From March 15, 2026 to September 1, 2026 there are 170 calendar days. The calendar breakdown is 5 months and 17 days, or 24 weeks and 2 days. There are 121 Monday-to-Friday dates when the earlier date is included and the later date is excluded.
These numbers are generated from the same date engine as the calculator. Selecting both endpoints changes the count to 171 days.
Why month-end dates need care
Months do not have equal lengths. From January 31, 2026 to March 1, 2026 is 29 days, represented here as 1 month and 1 day. The engine advances complete calendar months using constrained month-end dates, then counts the remaining days. It does not borrow a fixed 30 days from the previous month.
Reversing the two dates preserves the absolute duration and identifies the reversed order. Invalid dates, such as February 30, are rejected instead of silently becoming a day in March.
Add or subtract calendar days and weekdays
The 30, 60 and 90 days from today presets use your device's current local date and calendar-day mode. The example dates below are fixed so that the arithmetic is reproducible, not a live answer for today.
Choose Add / subtract days to find a future or past date. Adding 30 calendar days to October 4, 2026 produces 2026-11-03. Subtracting 30 returns 2026-09-04.
Weekday mode excludes the starting date and skips weekends. For example, five weekdays after Friday October 2, 2026 is 2026-10-09. A zero-day adjustment leaves the start date unchanged, even on a weekend.
Weekdays are not a holiday calendar
The tool does not automatically exclude public holidays, regional closures, or your employer's non-working days. Official deadlines can also use different inclusion and rollover rules. Check the relevant authority's rules before using any date estimate for a legal, tax, or contractual deadline.
Dates versus a live countdown
Use date difference for calendar spans. Use the Countdown Timer for a specific instant: choose a time and event time zone. Its days represent elapsed blocks of 24 hours, and its shared link preserves the same target instant across time zones.
Common questions
Does the date calculator include both dates?
By default it includes the earlier date and excludes the later date. Select Include both dates to add the final date. The same date therefore gives zero days by default and one day when both dates are included.
Does it remove public holidays?
No. The weekday count includes Monday through Friday only. It does not know your local holidays or workplace schedule. Subtract applicable weekday holidays separately.
Can I add or subtract days?
Yes. Choose Add / subtract days, enter a start date and a signed whole number, then choose calendar days or weekdays. Weekday mode skips Saturdays and Sundays, not holidays.
The date model uses Temporal.PlainDate calendar arithmetic.