Date / Time Calculator
This date calculator counts the days, weeks, months and hours between two dates, and adds or subtracts years, months and days from any date to give the resulting date and weekday.
About this tool
This date calculator counts the days, weeks, months and hours between two dates, and adds or subtracts years, months and days from any date to give the resulting date and weekday.
How to use it
- Choose Date Difference or Add / Subtract.
- For a difference, pick the start and end dates.
- To add or subtract, pick a start date, the operation and the years, months and days.
- Read the result instantly.
Good to know
- The difference counts whole days between the two dates; weeks are those days ÷ 7, rounded down.
- The month count is the number of calendar months between the dates, regardless of the day of the month.
- Adding time applies years first, then months, then days.
- Adding one month to January 31 rolls over into March, because February has no 31st.
Runs entirely in your browser — nothing you enter is uploaded or stored.
Frequently asked questions
How do I count the days between two dates?
Choose Date Difference and pick both dates. The tool shows the number of days, plus the same span in weeks, months and hours.
Does the day count include the end date?
No — it counts the days between the dates. Add one if you need to include both the start and end days.
How do I find the date 90 days from today?
Choose Add / Subtract, keep today as the start date, select Add and enter 90 days. The result shows the date and weekday.
Does it handle leap years?
Yes. It uses real calendar dates, so February 29 in leap years is counted automatically.