Date Calculator
Find the difference between two dates, or add/subtract days from a date.
What is the Date Calculator?
This tool answers the two most common date questions: "how much time is between these two dates?" and "what date is N days/weeks/months/years from this date?" — both calendar-aware, so month lengths and leap years are handled correctly rather than assuming every month has 30 days.
Difference between dates
This mode breaks the gap between two dates into years, months and days the way a calendar actually works — not just a raw day count divided by 365 — plus gives you the total number of days and weeks for cases where a single combined number is more useful (contract lengths, project timelines, "how many days until/since").
Add or subtract from a date
This mode takes a starting date and adds or subtracts a chosen number of days, weeks, months or years — useful for calculating deadlines, due dates, renewal dates or "N days from today" without counting on a physical calendar. Adding months or years correctly accounts for different month lengths (e.g. adding one month to January 31st lands on the last valid day of February).
How to use it
- Pick the mode you need.
- For a difference, enter both dates (either order works).
- For add/subtract, enter a starting date, choose add or subtract, an amount, and a unit.