Time/Numbers
Date Diff Calculator
Exact difference between two dates/times — calendar breakdown (years, months, days…), total duration, and business day count.
This tool calculates the exact difference between two dates and times: a calendar breakdown in years, months, and days, a total duration in a single unit (just days or hours), and separately, the number of business days excluding weekends.
How to use it
- Pick a start and end date (optionally with time and timezone) and the result is calculated instantly.
- The calendar breakdown reads naturally: "2 years, 3 months, 10 days" rather than just a raw day count.
- Business days are shown separately — weekends (Saturday and Sunday) are excluded from that count.
Common uses
- Working out how long a contract, warranty, or subscription runs in calendar units.
- Planning a project deadline in business days, excluding weekends.
- Calculating an age, tenure, or event duration down to the day.
Things to keep in mind
A calendar difference (years/months/days) depends on the actual dates involved — months have different lengths, so "1 month" can mean anywhere from 28 to 31 days.
The business-day count only excludes Saturday and Sunday — public holidays need to be subtracted manually if they matter for your calculation.
Article about this tool: Date difference: why counting days is trickier than it looks
Frequently asked questions
Is the difference calculated inclusive or exclusive of the end date?
The tool calculates the astronomical difference between two points in time (exclusive) — so "from the 1st to the 3rd" gives 2 days, not 3. If you need the number of calendar days inclusive of both dates, add one day.
How are months and years of different lengths handled?
The calendar difference (years/months/days) is computed the way a person would count on a calendar: full years and months are subtracted first, accounting for their actual length, and the remainder is expressed in days.
What do "business days" mean?
The number of Monday-through-Friday days in the selected period. Public holidays aren't accounted for, since they differ by country.
Why might different tools give different month-difference results near short months?
Subtracting a month from a date that doesn't exist in the previous month (e.g. March 31 minus a month) is ambiguous — some libraries round down to the last day of February, others roll the extra days into March. Both are logical, but they give different answers.
Can I calculate the difference for dates before 1970?
Yes, the calculation isn't limited to the Unix epoch and works correctly for any calendar dates, including ones before 1970.