Date Difference Calculator
Explain like I'm 5 (what even is this calculator?)
Pick two dates. Get the gap between them, in every unit that makes sense: years, months, days, weeks, hours, and weekdays. Useful for deadlines, anniversaries, and answering "how long has it been since…" without doing sums in your head on a Monday morning.
The gap is
–
We flipped the dates so the answer came out positive.
Every which way
- Years, months, days–
- Total days–
- Total weeks–
- Total months–
- Total hours–
- Business days (Mon-Fri)–
Show workings
What this is good for
Three things really: counting down (how long until the wedding, the holiday, the mortgage clearing), counting up (how long since a house move, a sobriety date, a contract started) and settling project-planning arguments ("can we launch in six weeks? Depends on what six weeks means on a calendar, doesn't it").
The business-days figure is the one project managers want. It counts Monday to Friday only, ignores weekends, and does not know about your national holidays. If you need bank holidays stripped out too, subtract them from the business-day figure by hand. Building a proper calendar-aware holiday subtraction is more calculator than this one wants to be.
How the maths works
Years, months and days come out of straightforward date subtraction with the same borrow-from-the-previous-month trick you'd use by hand. Total days uses UTC midnight on both dates, so daylight saving transitions and timezones cannot shunt the answer by one. Total weeks is the floor of total days divided by seven. Total hours is total days times twenty four, which is an approximation on the two days of the year that have twenty three or twenty five hours, but unless you're timing something to the exact minute that won't matter.
Related calculators
Date maths has a few obvious neighbours.
Common questions
Does it count the start date, the end date, or both?
The total-days figure counts the number of whole days between the two dates (Monday to Wednesday is 2). Business days are inclusive on both ends when those days are weekdays (Monday to Friday of the same week is 5).
What about bank holidays?
Not subtracted. Business days is strictly Mon-Fri. If you need a holiday-aware figure, knock the relevant bank holidays off by hand.
What if the end date is before the start date?
The calculator flips them, gives you a positive answer, and tells you it flipped them. No negative numbers to squint at.
Is any of my data sent anywhere?
No. Everything is worked out in your browser. The dates never leave your device.