Days between dates
Calculate how many days are between a start date and an end date.
When to use this calculator
Calculate days between dates, a D-day countdown, or a date a specified number of days before or after a base date.
- Planning deadlines, travel, or payment dates
- Counting down from a chosen reference date
- Finding a date after a waiting period
Worked examples
Date difference
July 1 to July 11 is a difference of ten days.
D-day
If the target is nine days after the reference date, the result is D-9.
Adding days
Ten days after July 11, 2026 is July 21, 2026.
Frequently asked questions
Is the start date included?
The calculator reports the elapsed difference between dates. Inclusive counting may require adding one day.
Can dates before the base be calculated?
Yes. Choose the before direction or enter the dates in reverse order.
Does time of day affect the result?
No. Calculations use calendar dates without times.
How to interpret the result
Official deadlines may have business-day, holiday, or end-of-day rules not included here.
Use the inclusive-counting rule specified by the relevant organization.