Date Calculator — Days Between Dates

This date calculator counts the days between two dates and finds the date a number of days, weeks, months or years before or after a given day. Instead of a single number, it breaks the duration into weeks and days, years, months and days, total months, weekdays, weekend days and hours. When adding or subtracting it follows the month-end rule exactly, and it can count business days that skip weekends and any holidays you list. Use it for contract periods, deadlines, trip planning and anniversaries.

How to use

1. On the "Between two dates" tab, pick the "Start date" and "End date".
2. "Start today" and "End today" fill in today's date, and "Swap dates" exchanges the two.
3. To count both the first and the last day, switch on "Include the end date".
4. Read the number of days under "Duration", together with "Weeks and days", "Years, months and days", "Months", "Weekdays", "Weekend days" and "In hours".
5. To add or subtract, open "Add or subtract", set "Start from", choose "Add" or "Subtract" and enter "Years", "Months", "Weeks" and "Days". The buttons for 100 days, 1000 days, 1 month, 6 months and 1 year fill these in for you.
6. "Resulting date" shows the date and its weekday, plus how many days that is "From the start date"; with "Calendar" counting it also shows the distance "From today".
7. To skip weekends, choose "Business days (no weekends)" under "Count by" and enter the number of "Business days". Add holidays in "Days off (holidays)", one per line, such as 2026-12-25.

How it works

• By default "Between two dates" counts the start date but not the end date, which equals the end date minus the start date. The 1st to the 3rd is 2 days, or 3 days with the end date included.
• When adding or subtracting, years and months are applied first, then weeks and days. If the target month has no such day, the last day of that month is used and a note says so.
• Business days are counted from the day after the start date. Holidays are never removed automatically; days off can be typed as YYYY-MM-DD, YYYY.MM.DD or YYYY/M/D, and entries that cannot be read are flagged.
• If the end date is before the start date, the time between them is still calculated and a warning is shown.
• Everything runs in the browser and nothing is uploaded. Your dates and the last tab you used are saved in this browser on this device.

Days between two dates: inclusive vs exclusive counting

From March 1, 2026 to December 25, 2026 is 299 days with the default counting. The page also shows that span as 42 weeks and 5 days, or 9 months and 24 days, of which 214 are weekdays and 85 are weekend days. Switching on "Include the end date" counts the last day as well and gives 300 days.

Which number is right depends on what you are counting. Nights in a hotel or the plain difference between dates exclude the end date; workdays attended or the days of an event usually include both ends. January 1 to December 31, 2026, counted inclusively, is 365 days. Legal and contractual deadlines often have their own counting rules, so check the wording or ask the issuing body when a deadline really matters.

How to add months to a date and the month-end rule

Adding one month to January 31 lands on the last day of February, because February has no 31st: February 28 in 2026 and February 29 in the leap year 2028. Subtracting one month from March 31, 2026 also gives February 28. Since months are applied before days, January 31, 2026 plus 1 month and 1 day is the day after February 28, which is March 1.

Months between two dates follow the same rule. May 15, 2025 to October 18, 2026 is 1 year, 5 months and 3 days, shown as 17 months plus 3 days, or 521 days in total. February 29, 2024 to February 28, 2025 counts as exactly one year because both are month ends.

Adding business days and handling public holidays

Business days are counted one by one from the day after the start date, Monday to Friday only. Adding 5 business days to Friday, December 18, 2026 gives Friday, December 25; enter 2026-12-25 under "Days off (holidays)" and the result moves to Monday, December 28. "Days skipped" then shows 5: four weekend days and one holiday.

Holidays are not built in because public holidays differ by country and region, substitute days change every year, and many employers have their own closures. Listing only the days that apply to you keeps the count exact. Note that the weekday count on "Between two dates" does not remove holidays, so subtract them yourself when you need working days.

Questions and answers

What date is 100 days from today?

On "Add or subtract", keep today as the start date and press the 100 days button to see the date and weekday. If today counts as day 1, day 100 is 99 days later.

How do you count the days between two dates?

Subtract the start date from the end date. March 1 to March 10 is 9 days, or 10 days if both dates are counted.

What is January 31 plus one month?

The last day of February: the 28th in a common year and the 29th in a leap year.

Does it leave out public holidays?

Not automatically. With "Business days (no weekends)", the dates you enter under "Days off (holidays)" are skipped too.

How many days until a date?

Press "Start today" and put the target in "End date"; "Duration" is the number of days left.

How many weeks are between two dates?

See "Weeks and days". For example, 299 days is 42 weeks and 5 days.

What is the date 6 months from now?

Press the 6 months button on "Add or subtract". Six months after October 18, 2026 is April 18, 2027.

Can I find a date in the past?

Yes. Choose "Subtract" and enter days or months; 90 days before March 1, 2026 is December 1, 2025.

How are the months between two dates counted?

Each time the same day of the month comes round counts as one month, and the rest is shown as extra days. May 15, 2025 to October 18, 2026 is 17 months plus 3 days.