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

Enter two dates and the calculator will show total days, weeks, and calendar difference automatically.

How does the D-Day countdown work?

Enter a target date in countdown mode and the calculator shows the number of days remaining or elapsed.

Calculate the number of days, weeks, and calendar differences between two dates. You can also add or subtract dates and run a countdown.

Start date

End date

Total difference365 days

Years / months / days1y 0m 0d

Weeks / days52w 1d

Start weekdaySat

End weekdaySun

Date difference: Compare two dates and see total days, weeks, and calendar difference.
Add or subtract: Add years, months, or days to a base date.
Countdown: Track days remaining until a target date, or days since it passed.

In add/subtract mode, enter 100 in the days field to see the resulting date and weekday.

Can I calculate only business days?

Not yet. This calculator shows total calendar days, so you need to subtract weekends and holidays separately.

How can I estimate a due date?

Set the start date to the first day of the last menstrual period and add 280 days in add/subtract mode.

How do I calculate 100-day or 200-day anniversaries?

Use add/subtract mode and add 99 days to the start date if you count the start day as day 1.