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Date Calculator

Count the days between two dates, including business days, or add and subtract days from a date.

Days between two dates

Enter a start date and an end date to count the days between them.

Add or subtract days

Choose a start date to see the resulting date.

How to use

  1. To count days, pick a start date and an end date. Both default to today and the last day of this year.
  2. Check "Include the end date" if the last day should count too, for example for a booking or a time-off request that covers both days.
  3. Read the calendar-day total at the top. Just below it, "Business days (Mon–Fri)" shows the same range without Saturdays and Sundays.
  4. To find a date in the future or past, go to "Add or subtract days", choose the start date, pick Add or Subtract and enter years, months, weeks or days.
  5. Read the resulting date with its weekday. Every result updates as you type.

How days between dates are counted

The calculator turns each date into a plain day number on the Gregorian calendar and subtracts one from the other. Because it works with whole calendar days rather than clock time, daylight saving changes and time zones never add or remove an hour that could tip the result by a day. Leap years are handled automatically: February has 29 days in years divisible by 4, except century years that are not divisible by 400, so 2024 and 2000 had a February 29 but 2100 will not.

The default answer counts the start date and stops before the end date. From January 1 to December 31, 2026 that gives 364 days; check “Include the end date” and you get 365, the full length of the year. Which version you need depends on the question. “How many nights is my stay?” excludes the end date. “How many days off am I taking from Monday to Friday?” includes it.

Weeks and months

The same span is also shown in weeks plus days and in months plus days. Months are counted the way people usually count them: one month has passed when the same day number comes around again, so January 15 to April 15 is exactly three months, even though those months have different lengths. If the start day does not exist in a shorter month, the last day of that month is used instead. From January 15 to April 20, 2026, for example, the calculator shows 95 days, 13 weeks and 4 days, or 3 months and 5 days.

Business days

Next to the calendar-day total, the tool always shows the business days in the same range, with Saturdays and Sundays skipped. It counts full weeks as five business days each and then checks the few leftover days one by one, so long ranges are as fast as short ones. Across the whole of 2026 there are 261 weekdays, also called working days (check “Include the end date” so that December 31 counts too; without it the tool shows 260). Public holidays are not removed, because they depend on where you live and who you work for. If your contract says “within 10 business days”, count the business days and then subtract any holidays that fall inside the range.

Adding and subtracting dates

The second part of the tool moves a date forward or back. Years and months are applied first, then weeks and days. This order matters at the end of a month: January 31 plus one month lands on February 28, and one more day gives March 1. Doing the days first would give a different date, which is why calendar apps and most programming libraries follow the same months-first rule used here.

Underneath the resulting date you also see how many calendar days separate it from the start date. That is handy when a deadline is written as “90 days” but you would rather think in months, or the other way around.

Practical uses

  • Working out a notice period, a probation end date or a warranty expiry.
  • Counting down to a trip, an exam or a due date.
  • Checking how many business days a project or an invoice term really gives you.
  • Finding the date 6 months or 1 year after a contract starts.

For someone’s exact age in years, months and days, or how many days old a person is, the age calculator works from a date of birth and also counts down to the next birthday.

Frequently asked questions

Does the day count include the start date and the end date?

By default the result is the difference between the dates, which counts the start date but not the end date — the same answer you get from a spreadsheet when you subtract one date from another. Check "Include the end date" to add one day so both ends are counted.

Are public holidays excluded from business days?

No. Business days here are simply Monday to Friday. Holidays differ by country, state and employer, so subtract any that fall in your range yourself.

What happens if the end date is earlier than the start date?

The calculator swaps them and shows the distance as a positive number, with a note that the dates were reversed. The count is the same in either direction.

What do I get if I add one month to January 31?

February 28, or February 29 in a leap year. When the target month is shorter, the date moves to that month's last day instead of spilling over into March.

In what order are years, months, weeks and days added?

Years and months first, then weeks and days. Adding one month and one day to January 31, 2026 gives February 28 plus one day, which is March 1.

How many days are left until a specific date?

Leave the start date as today, set the end date to the event, and read the calendar-day total. Check "Include the end date" only if you want to count the event day itself.

Is a week always counted as seven days?

Yes. The "In weeks" figure divides the total by seven and shows the leftover days separately, so 17 days becomes 2 weeks and 3 days.

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