About the Date Difference Calculator
The Date Difference Calculator tells you how much time lies between two dates. You get the number of days and weeks, how many of those days are weekdays and weekend days, the gap in years, months and days, and the same span in hours, minutes and seconds.
It answers everyday planning questions: how long a project or a contract runs, how many working days are left before a deadline, how many days a trip or a hotel stay lasts, how long ago something happened, or how many days an invoice is overdue.
The calendar math handles leap years and months of 28 to 31 days. You can count the end day too, add clock times for partial days, and swap the dates with one click. Everything runs in your browser.
How to use it
- Pick the two datesChoose a start date and an end date. The tool opens with January 1 of this year and today.
- Decide whether the end day countsCheck "Count the end day too" when both the first and the last day should be included, as with a hotel stay counted in days or a vacation.
- Add times if you need themCheck "Include times" to set a clock time for each date. Days, hours and minutes then count only complete periods.
- Use a shortcutEnd is today, To end of year (from today to December 31) and Start + 100 days fill in the dates for you.
- Read and copy the resultRead the totals at the top and the breakdown below, then click Copy result for a one-line summary.
Key features
Days, weeks and weekdays
The number of days, the same span in weeks and days, and how many of those days fall Monday to Friday or on a weekend.
Years, months and days
A calendar breakdown such as "5 months, 19 days", also shown as months and days only.
Hours, minutes and seconds
The span in smaller units, either for whole days or for the exact times you enter.
Leap years and month ends
February 29 is counted in leap years, and a month from January 31 ends on the last day of February.
Order does not matter
If the end date is before the start date, the tool swaps them and says so.
Private by design
Both dates are worked out on your device. There is no account, and nothing is uploaded.
Examples
A whole year
| Dates | Days | Breakdown | Weekdays |
|---|---|---|---|
| Jan 1 to Dec 31, 2026 | 364 | 11 months, 30 days | 260 |
| Same, counting the end day | 365 | 1 year | 261 |
| Jan 1, 2024 to Jan 1, 2025 | 366 | 1 year | 262 |
By default the tool counts from the start date up to the end date, the way you count nights in a hotel. Checking "Count the end day too" adds the last day. 2024 was a leap year, so a full year from January 1, 2024 has 366 days.
Weekdays and weekends
| Dates (2026) | Days | Weekdays | Weekend days |
|---|---|---|---|
| Mon, Oct 5 to Fri, Oct 9 | 4 | 4 | 0 |
| Same, counting the end day | 5 | 5 | 0 |
| Fri, Oct 9 to Mon, Oct 12 | 3 | 1 | 2 |
Weekdays are counted from the start date and stop the day before the end date, unless you count the end day too. A full work week from Monday to Friday is therefore 5 weekdays only with that box checked. Public holidays are not taken into account.
Months of different lengths
| Dates | Days | Breakdown |
|---|---|---|
| Jan 31 to Mar 1, 2026 | 29 | 1 month, 1 day |
| Jan 31 to Feb 29, 2024 | 29 | 1 month |
February has no 31st, so one month after January 31 is the last day of February: February 28 in 2026, February 29 in the leap year 2024. That is why the same 29 days can be "1 month, 1 day" in one year and exactly "1 month" in another.
Dates with times
From January 1, 2026 at 10:00 AM to January 2 at 9:00 AM is 0 days and 23 h 0 min (1,380 minutes), because a full day has not passed yet. Without times, the same dates count as 1 day.
Hours always count every day as 24 hours, and both times are read on the same clock. From March 7, 2026 at noon to March 9 at noon shows 48 hours. In most of the United States, clocks moved forward one hour on March 8, 2026, so only 47 hours actually passed there. For times in two different time zones, convert one of them first.
A project timeline
From Monday, October 12, 2026 to Wednesday, March 31, 2027: 170 days, 24 w 2 d, 5 months, 19 days and 122 weekdays. Subtract the holidays your team takes off, such as Thanksgiving, Christmas and New Year's Day, to get the real number of working days.
Tips
- For hotel stays and rentals, leave "Count the end day too" off: the result is the number of nights. For vacations and events counted in days, check it.
- For working-day deadlines, start with the weekday count and subtract public holidays and planned days off.
- Use "Start + 100 days" for a 100-day plan or a probation period, then adjust the end date to a weekday if needed.
- To find out how long ago something happened, put that date first and click "End is today".
- For someone's exact age, the Age Calculator shows the same breakdown plus the next birthday.
Common mistakes and limits
- Forgetting whether the end day countsFrom Monday to Friday is 4 days by default and 5 with "Count the end day too". Decide which one your question needs.
- Treating weekdays as business daysWeekdays are Monday to Friday. Public holidays differ by country and state, so they are not removed.
- Expecting hours to include daylight saving changesEvery day counts as 24 hours. Across a spring or fall clock change, the real elapsed time is one hour less or more.
- Comparing month counts across yearsMonths have different lengths, so "1 month" can be 28, 29, 30 or 31 days. Use the day count when precision matters.
- Entering times from different time zonesBoth times are read on the same clock. Convert one of them to the other's time zone before you enter it.
