How This Calculation Works
The date duration calculator finds the difference between two dates in multiple units: calendar days, weeks, months, and business days (excluding weekends).
Business days exclude Saturdays and Sundays but do not account for public holidays, which vary by country.
Common Mistakes to Avoid
- Confusing inclusive vs exclusive counting. This calculator counts the days between the two dates, not including both endpoints.
- Forgetting holidays. Business day counts do not include public holidays. Subtract them manually for project planning.
Worked Example
Scenario: From January 1, 2026 to March 31, 2026.
Calendar days: 89 days.
Weeks: 12.7 weeks.
Months: 3 months.
Business days: ~63 days (minus any holidays).