Date Calculator
Days between two dates, or add and subtract time from one.
About this calculator
Two date jobs, one tool. Difference mode counts the time between two dates — total days, weeks, a calendar breakdown, and how many of those days are weekdays, which is what deadlines usually care about. Add/subtract mode moves a date forwards or backwards by days, weeks, months or years: '90 days from today' or 'three months before the deadline'.
All the arithmetic follows the real calendar — 30- and 31-day months, February, and leap years included — rather than assuming every month has 30 days.
Frequently asked questions
How do I count the days between two dates?
Pick difference mode, enter the start and end dates, and read off the total days along with weeks and a calendar breakdown. The weekday count sits alongside it, since 'ten working days' and 'ten days' are rarely the same thing.
What happens when I add a month to 31 January?
There is no 31 February, so the result clamps to the last real day of the month — 28 February (29 in a leap year). That's the standard calendar-arithmetic rule and it keeps every result a date that actually exists.
Are leap years handled?
Yes — every calculation runs on the real calendar, so February has 29 days in leap years and date differences across them come out exact.