Date Difference Calculator
Find the exact number of days, weeks, months, and years between any two dates.
How the date calculator works
Enter two dates and the tool calculates the exact difference in days, weeks, months, and years. It accounts for leap years and varying month lengths automatically.
What is a business day?
A business day is Monday through Friday, excluding holidays. The calculator treats Saturday and Sunday as non-business days. For exact accounting (e.g., legal documents), always check your jurisdiction's holiday calendar.
Date calculation formulas
- Days: Simple subtraction (accounts for leap years).
- Weeks: Days / 7.
- Months: Difference in calendar months (approximate).
- Years: Difference in calendar years with month/day adjustment.
Common uses
Age calculators, project timelines, contract duration, maternity leave planning, historical date spans, and countdown to events.
Frequently asked questions
Does this include the start date or end date?
By default, the start date is included but the end date is not (standard in date arithmetic).
How accurate is the business day count?
Accurate for Sat/Sun weekends, but does not account for public holidays - add or subtract days manually for holidays.