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Date & Time

Date Difference Calculator

Calculate the exact difference between two dates in years, months, weeks, and days.

Total Days
0
days between dates
Weeks
0
Months
0
Years
0
Weekends
0

How to Calculate the Difference Between Two Dates

Date difference calculations are essential for project planning, contract management, age verification, interest calculations, and deadline tracking. This calculator provides the exact number of calendar days, business days (weekdays), weeks, months, and years between any two dates.

Toggle "exclude weekends" to count only business days — essential for project timelines where work only happens Monday through Friday. The calculator does not account for public holidays; that varies by country and region.

How Date Difference Is Calculated

Total Days = (End Date − Start Date) / 86,400,000 ms Business Days = Total Days − Weekend Days Weeks = Total Days / 7 Months = year difference × 12 + month difference

Common Date Difference Use Cases

Use CaseExample
Contract durationDays between signing and expiry
Loan interest periodDays between disbursement and payment
Event planningDays until conference, wedding, launch
Age verificationDays since birth for legal minimum age
Project timelineBusiness days available for delivery

Frequently Asked Questions

By default, the calculator counts the difference as the end date minus the start date, which includes neither the start nor end date in the count (like counting the gap between two fence posts). To include both dates, add 1 to the result.
Business days are calendar days minus Saturdays and Sundays. This calculator does not subtract public holidays, since these vary by country, state, and company policy. For project planning, subtract expected holidays manually.
Yes — you can enter any valid calendar date in the date fields, including dates in the past. The calculator handles dates going back to January 1, 1000 CE using the Gregorian calendar system.
A standard year has 365 days. A leap year has 366 days. Leap years occur every 4 years (divisible by 4), except for century years not divisible by 400. For example: 2000 was a leap year; 1900 was not. Our calculator correctly accounts for leap years.