Time & Date · Date Math
Date Difference Calculator
Calculate the exact time between two dates in years, months and days, with total days, weeks, hours and minutes, and the number of working days after skipping weekends and the holidays you list.
How this is calculated
Years, months, days: step whole months from the earlier date (clamping to month ends), then count the remaining days
- Working days
- Days from the start (inclusive) to the end (exclusive) that aren't weekend days or listed holidays; negative if the end is earlier
- Include end date
- Adds one day so both the start and end dates count
The years-months-days answer walks the calendar month by month from the earlier date, so it reflects real month lengths rather than a 30-day average — 31 January to 29 February 2024 is exactly 1 month. Total days count the gap between the dates (1 to 3 March is 2 days); switch on 'include the end date' to count both ends. If the end date is before the start date, every figure is shown as negative.
Assumptions & sources
- Dates are whole calendar days in one time zone; hours and minutes are whole days × 24 × 60.
- Working days use your weekend setting (Saturday–Sunday by default) and the holidays you list.
- 1ISO 8601 — Date and time format (week numbering, calendar dates) — International Organization for Standardization
- 2Calendrical Calculations (Reingold & Dershowitz) — Cambridge University Press
Calculator ID TIME-DATEDIFF-001 · version 2.0.0
Common questions
How many days are there between two dates?
The count of days from the start date up to, but not including, the end date — for example 1 to 3 March is 2 days. Turn on 'Include the end date' to count both, giving 3.
Why can't months be converted exactly to days?
Months have 28 to 31 days, so the calculator counts whole calendar months first and then the leftover days. The 'total months' figure divides those leftover days by an average month of 30.44 days.
How are working days counted?
Every day from the start date up to the end date that isn't one of your weekend days and isn't a holiday in your list. If the end is before the start, the count is negative, matching the other figures.