Date Difference Calculator
Calculate the exact time between any two dates. The result is shown several ways at once: total days, weeks plus days, and a calendar breakdown in years, months, and days. Turn on “include end date” when both dates should count, such as for an event, work schedule, or medication course.
Calculators
Private by default
This tool runs entirely in your browser. Your data is never uploaded to a server.
How it works
How the difference is counted
Total days = end date − start date, plus 1 when the end date is included
Both dates are read as calendar days at midnight and the elapsed time is rounded to whole days, so a daylight-saving change never adds or drops one. The years-months-days breakdown is a separate calculation: it steps whole calendar months forward from the start date and then counts the leftover days.
- The default measures the distance between dates: Monday to Tuesday is 1 day. “Include end date” makes it 2 calendar days. Use that for inclusive schedules or medication courses; leave it off when counting hotel nights.
- Weeks are shown as whole weeks plus the remaining days, so 30 days reads as 4w 2d.
- Reversing the two dates changes nothing: the earlier one is always treated as the start.
- The calendar breakdown always describes the two dates you entered, so it does not shift when you tick “include end date”.
- The breakdown is not the total divided by 30.44: one month after January 31 is February 28 or 29, not a fixed number of days later.
For reference
How many days is that, exactly?
The periods people ask about most, in days and in weeks.
| Period | Days | Weeks |
|---|---|---|
| 1 week | 7 | 1 |
| 2 weeks | 14 | 2 |
| 1 month (28 days) | 28 | 4 |
| 1 month (30 days) | 30 | 4.29 |
| 1 month (31 days) | 31 | 4.43 |
| 1 quarter (Jan 1 → Apr 1) | 90 | 12.86 |
| Half a year (Jan 1 → Jul 1) | 181 | 25.86 |
| 1 common year | 365 | 52.14 |
| 1 leap year | 366 | 52.29 |
“A month” is only exact once you name both dates — calendar months run from 28 to 31 days. The quarter and half-year rows assume a common (non-leap) year.
How to use
4 clear steps.
Pick the start date.
Pick the end date.
Toggle "include end date" if you need an inclusive count.
Read the difference in days, weeks, months, and years.
Good to know
Frequently asked questions
- Why do I get 1 day between today and tomorrow?
- By default, consecutive dates are one day apart. Enable “include end date” only when both calendar dates should count—for example, an event running Monday through Tuesday. When counting hotel nights, leave it off because the checkout date is not a night.
- Does it handle leap years?
- Yes. The calculation uses real calendar dates, so February 29 and different month lengths are automatically accounted for.