Date Duration Calculator
Common year
days
How the Date Duration Calculator Works
This calculator determines the exact difference between any two dates. It counts calendar days by default, but you can switch to business days by excluding weekends. The result includes a full breakdown into weeks, months, and years, plus total hours, minutes, and seconds.
Formula: Duration = End Date − Start Date
Example: Jan 1, 2026 to Dec 31, 2026 = 364 days
Business Days Explained
Business days (also called working days) exclude Saturdays and Sundays. This is essential for contract deadlines, SLA calculations, project planning, and legal notice periods. In a typical 30-day month, there are approximately 22 business days, though the exact count depends on the specific dates.
Common Use Cases
The date duration calculator is widely used for project timeline planning, counting days until a deadline, calculating contract periods, travel planning, tracking elapsed time since an event, computing payment terms (Net 30, Net 60), and determining legal notice periods. The add/subtract mode is particularly useful for finding future deadlines by adding a specific number of business days to today.