Date Calculator

Count the days between two dates, or add and subtract days, weeks, months and years from a date.

By the PunchClockCalc team · Last updated

To count the days between two dates, subtract the start date from the end date. The start day is not counted, but the end day is, so November 3 to December 25, 2026 is 52 days. Tick “include end date” to count both days. To add months, move the month first, then add days.

Days between two dates

Days–
Weeks and days–
Years, months, days–
Hours–

Add or subtract days, weeks, months or years

Result–

How do I use the date calculator?

  1. Pick a start date and an end date in the first box. Use the Today buttons to fill in today's date from your device.
  2. Decide whether to include the end date. Leave it unticked for a normal difference, or tick it to count both the first and last day.
  3. Read the result in days, in weeks and days, and in years, months and days. If the end date is before the start date, the difference is shown as a negative number.
  4. To find a date in the future or past, use the second box: choose a start date, pick add or subtract, and enter any mix of years, months, weeks and days.

How is the number of days between two dates calculated?

Each date is turned into a day number on the Gregorian calendar, and the earlier number is subtracted from the later one. That is the same as counting forward one day at a time from the start date and stopping on the end date. Leap days are counted automatically: February 2024 had 29 days, so February 28 to March 1, 2024 is 2 days, while the same dates in 2026 are only 1 day apart.

The years, months and days breakdown counts whole months from the start date first, then the days left over. Because months have different lengths, 30 days is not always “1 month”: from January 1 to January 31 is 30 days but 0 months, while February 1 to March 1 is a full month of only 28 days.

Worked examples

Example 1: days between two dates

From Tuesday, November 3, 2026 to Friday, December 25, 2026 is 52 days. That is 7 weeks and 3 days, or 1 month and 22 days.

Example 2: a whole year, counting both ends

January 1 to December 31, 2026 is 364 days by subtraction. Tick include end date and it becomes 365 days, exactly 1 year, because both January 1 and December 31 are counted.

Example 3: 90 days from a date

November 3, 2026 + 90 days = Monday, February 1, 2027. Six months before November 3, 2026 is Sunday, May 3, 2026.

Example 4: adding a month to January 31

February has no 31st, so January 31, 2026 + 1 month = Saturday, February 28, 2026, the last day of February. In the leap year 2028 the same step lands on Tuesday, February 29, 2028. Going the other way, January 31 to March 1, 2026 counts as 1 month and 1 day.

How do you add months or years to a date?

Years and months are added first, then weeks and days. When the new month is too short for the original day number, the date moves back to the last day of that month: March 31 minus 1 month is February 28, and February 29, 2024 plus 1 year is February 28, 2025. Adding weeks is the same as adding 7 days per week, so 2 weeks from any Tuesday is always a Tuesday.

What are common uses for a date calculator?

Frequently asked questions

Does the date calculator include the end date?

Not by default. Like most date calculators and spreadsheets, it counts the days after the start date up to and including the end date, so Monday to Tuesday is 1 day. Tick include end date to count both days, which is what you want for things like hotel nights versus event days, or a leave request that includes the first day.

How do I calculate the number of days between two dates in Excel?

Subtract the cells: =B1-A1, or use =DAYS(B1,A1). Add 1 to include both dates. For years, months and days, use =DATEDIF(A1,B1,"y"), "ym" and "md". Note that DATEDIF's "md" unit can give odd results at month ends.

What is 1 month after January 31?

February 28 (February 29 in a leap year: February 29). When the target month is shorter, the date moves back to that month's last day. This is called month-end clamping and matches how banks, leases and most software count months.

Do time zones or daylight saving time change the result?

No. The calculator works with calendar dates only, never clock times, so a daylight saving change or your time zone cannot add or remove a day. Only the default “today” comes from your device's own date.

How are leap years handled?

Every leap day is counted. A year is a leap year if it divides by 4, except century years, which must divide by 400. So 2000 and 2024 were leap years, and 2100 will not be.

Can I count only working days?

Yes. Use the business days calculator to skip weekends and, if you want, U.S. federal holidays.

More free date & time tools

Business Days CalculatorWorking days between dates, minus weekends and U.S. federal holidays; add business days.Days Until CalculatorCountdown to Christmas, New Year, Thanksgiving or any date.Age CalculatorExact age in years, months and days, and days to your next birthday.Week Number CalculatorISO week number for any date, the current week and every week of the year.Hours CalculatorTime between two times; add or subtract hours.Time Card CalculatorWeekly hours, lunch breaks, overtime and pay.