Date Calculator
Find the exact gap between two dates in years, months, and days, or add and subtract time from any date and see the weekday it lands on. Every calculation runs in your browser.
Enter two valid dates to see the difference.
How to use it
1. Pick a mode
Choose "Difference between dates" to measure a gap, or "Add or subtract" to shift a date.
2. Enter the dates
Type or pick the dates. The tool shows the weekday for each one as you go.
3. Read the result
See the gap in years, months, and days plus totals, or the resulting date and its weekday.
4. Copy it
Copy a plain-text summary of the result with one click.
Common questions
How does the date difference get counted?
The difference is the whole calendar gap from the first date to the second. It is shown two ways: as years, months, and days, and as a plain total of days (and whole weeks). Month lengths are respected exactly, so a span like January 31 to March 1 reads as one month and one day, not a rounded guess.
What happens when I add a month to the end of a month?
The day is clamped to the target month. Adding one month to January 31 lands on February 28, or February 29 in a leap year, because those are the last days of February. This matches how calendars and spreadsheets handle month math.
Does it handle leap years correctly?
Yes. February 29 is accepted only in leap years, and spans that cross a leap day count the extra day. The year 2000 counts as a leap year and 1900 does not, following the standard Gregorian rule.
Do my dates get sent anywhere?
No. All of the math runs in your browser on your own device, so nothing about your dates is uploaded to a server. The tool keeps working the same way offline once the page has loaded.