Date Difference Calculator
Calculate the number of days, weeks, months and total days between two dates. Great for deadlines, ages and planning.
Month-end rule: calendar anniversaries are clamped to the last valid day (January 31 → February 28/29). The day-count convention changes the total, not the endpoint calendar breakdown.
Working days only? Business days · birthday age: Age calculator · countdown to date: Event countdown.
How to use
Pick a start and end date, choose which endpoints count, or add N calendar days or weekdays to any date. Weekday mode uses Mon–Fri only; public holidays are outside this calculation because no holiday calendar is applied.
FAQ
How is the difference counted?
The default is elapsed days: exclude the start date and include the end date. You can instead include both dates, include only the start, or exclude both.
How are months calculated?
Calendar years and months use clamped anniversaries: if the target month has no matching day, the anniversary moves to that month’s last day, such as January 31 → February 28 or 29.
Can I use it for age?
Yes — set the start date to a birthday and the end date to today to see the elapsed years, months and days.
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