Date Calculator
Find the difference between dates and add calendar or business days.
Inputs
Results update as you edit.
Date difference
239 days
Results update as the calculator inputs change.
Weeks
34.14
Signed difference
239 days
Date after add-days
Jun 5, 2026
ISO date
2026-06-05
How to Calculate Date Differences
How to Use Date Math
Date calculations are useful for deadlines, timelines, billing periods, projects, and scheduling. Calendar days and business days answer different planning questions.
What Affects Date Calculations?
Common Date Calculator Uses
Days Between
Find elapsed days between two dates.
Add Calendar Days
Add a fixed number of days to a start date.
Add Business Days
Plan work timelines by excluding weekends.
Frequently Asked Questions
What is the difference between calendar days and business days?
Calendar days include every day. Business days usually skip weekends.
Are holidays excluded?
No. This calculator skips weekends in business-day mode but does not know your holiday calendar.
Is the start date counted?
Elapsed-day calculations usually count the time after the start date. Specific contracts may define this differently.
Can I add negative days?
If supported, negative days move backward from the start date.
Why do date results differ across tools?
Different tools may use inclusive counting, holiday calendars, or time-zone assumptions.