Date Difference Calculator: Days, Weeks, Months and Years Between Dates
Counts the days, weeks, months and years from one date to another.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
days = end date − start date weeks = days ÷ 7 decimal years = days ÷ 365.2425
Months and calendar years are not a fixed number of days, so they are counted on the calendar. Decimal years use the average length of a Gregorian year.
What to watch out for
The start date is not counted, so tomorrow is 1 day away. Add one if both the first and last days count, as they do for a course that runs on both dates. That figure is shown too.
Frequently Asked Questions
How many days are there between two dates?
Subtract one from the other on the calendar. From 1 January 2025 to 1 January 2026 is 365 days, and from 1 January 2024 to 1 January 2025 is 366, because 2024 was a leap year.
How are months between dates counted?
By stepping through the calendar from the start date. From 15 January 2025 to 20 March 2025 is 2 months, 5 days.
Should I count the first day?
For how long until or since, no. For a span of days you actually occupy, such as a course or a contract running from one date to another, usually yes.