Date Calculator
Count the days between two dates, including or excluding the end date, and see the span in weeks, months and business days. You can also add or subtract days, weeks, months or years from any date, or count down to an event with a D-day timer. Everything is calculated in your browser.
Pick two valid dates to see the difference.
How to use the date calculator
- Choose a mode. Pick Days between dates to measure a span, Add / subtract to move a date forward or back, or D-day countdown to count down to an event.
- Enter the dates. Type or pick a start and end date (or a target date). The Today button fills in your current local date, and Swap reverses the two dates.
- Set the options. Tick Include the end date to count both days, or Count days as business days to skip Saturdays and Sundays when adding days.
- Read the result. Results update as you type: total days, weeks and days, years, months and days, business days, the resulting date and its weekday, or a live D-day countdown.
Inclusive vs exclusive day counts
Subtracting two dates gives the number of nights between them: from Monday to Friday is 4 days. That is the right answer for elapsed time, interest periods and “how many days until”. If you are counting the days on which something happens and both the first and last day count, as with a leave request or a festival from the 1st to the 5th, include the end date to get 5.
The years/months/days breakdown follows the same rule and adds months the way calendars do. From 15 January to 14 February is 30 days, not one month; from 15 January to 15 February is exactly 1 month. To find someone’s exact age, use the Age Calculator, which also shows the next birthday.
Business days and deadlines
Contracts, shipping estimates and notice periods are often stated in business days. The calculator treats Monday to Friday as working days. Adding 10 business days to a Wednesday lands on the Wednesday two weeks later; adding 1 business day to a Friday or a weekend lands on Monday. Public holidays vary by country and are not removed, so subtract them yourself if your deadline depends on them.
- Exclusive count: start date counted, end date not.
- Inclusive count:both dates counted, the same as Excel’s NETWORKDAYS.
- Adding business days:the start date is not counted, like Excel’s WORKDAY.
Related tools
Frequently Asked Questions
How do I calculate the number of days between two dates?↓
Enter a start and end date in the Days between dates tab. The calculator subtracts the calendar days, so 1 March to 31 March is 30 days. Tick Include the end date to count both days, which gives 31. The same result is also shown in weeks and days, months and days, and years, months and days.
Should the end date be included?↓
It depends on what you are counting. For elapsed time, such as how long until a deadline, leave it excluded. For counting days of something that happens on both dates, such as a hotel stay's calendar days, a leave period or an event running from the 1st to the 5th (5 days), include it. Including the end date always adds exactly one day.
How are business days counted?↓
Business days are Monday to Friday. With the end date excluded, the start date is counted and the end date is not; with it included, both are counted, which matches Excel's NETWORKDAYS. When adding business days, the start date is not counted and the result always lands on a weekday, like Excel's WORKDAY. Public holidays are not removed because they differ by country.
What is January 31 plus one month?↓
February 28, or February 29 in a leap year. When the target month is shorter, the date is clamped to that month's last day, which is how spreadsheets and most programming libraries add months. Likewise, February 29 plus one year is February 28 of the next year.
What does D-day mean, and how is D-100 counted?↓
D-day is the target date. D-100 means 100 days remain, D-1 is the day before and D+5 is five days after. For anniversaries counted from the first day, such as 100 days together, tick Count the date itself as day 1: day 100 then falls 99 days after the start date.
Can daylight saving time make the day count wrong?↓
Not here. The calculator works with whole calendar dates rather than hours, so a 23- or 25-hour day at a daylight saving change never shifts the result by one. Only today's date is read from your device's local time zone.
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