Date Difference Calculator
Pick a start and end date to find the total number of days between them, and the breakdown in years, months, and days.
How date differences are calculated
This calculator counts the number of calendar days between your start and end dates, including the effect of different month lengths and leap years.
The years/months/days breakdown works like a calendar count: it finds the largest whole number of years, then months, then days that fit between the two dates — the same way you'd describe someone's exact age or the exact length of a project.
Frequently asked questions
Does the day count include both the start and end date?
The total days shown is the number of days between the two dates (the difference), not an inclusive count — so January 1 to January 2 is 1 day.
How does the calculator handle leap years?
It uses real calendar dates, so February 29 in a leap year is counted correctly and doesn't need any special handling from you.
Can I calculate a date in the past?
Yes, as long as the end date is on or after the start date, so you can use any two dates — past, present, or future — to measure the gap between them.