Date Difference Calculator
Find the exact time between two dates in days, weeks, months, and business days.
Pick a start and end date. Get the calendar difference plus total days, weeks, months, and business-day count.
How the difference is calculated
The calendar difference (years, months, days) walks the calendar from start to end, handling varying month lengths and leap years. The total counts (days, weeks, months) are pure arithmetic over the elapsed period.
Business days
Business days exclude Saturdays and Sundays. This calculator does NOT exclude federal holidays. For project planning where holidays matter (Thanksgiving, Christmas, etc.), subtract them manually from the business-days count. Major US holidays typically remove 8-10 business days per year.
Common uses
- Project timelines: how long until a deadline, how long a project took
- Pregnancy / gestation: days between LMP and due date
- Anniversary planning: how many days until / since
- Tenure: exact years and months of employment
- Contract math: elapsed time between contract dates
- Loan / lease term: exact length of an agreement
Including or excluding endpoints
This calculator counts from start to end inclusive of both endpoints for business days (so Mon-Fri returns 5 business days), and uses standard "days between" math for the total. Some conventions count only the start or only the end; check your specific use case.