Date & Time Calculator
Date Calculator
Add or subtract days, weeks, months, or years from a date.
Operation
Date after
March 2, 2025
How it works
Pick a starting date, an amount, a unit, and whether to add or subtract — the calculator handles month-length differences and leap years automatically, so "3 months after January 31" correctly lands on a valid date instead of overflowing.
Formula
Resulting date = Start date ± Amount (in the chosen unit)
Example
60 days after January 1, 2025 is March 2, 2025.
Frequently asked questions
What happens when adding months lands on a day that doesn't exist?
For example, adding 1 month to January 31 can't land on "February 31" — JavaScript's date handling rolls it forward to the next valid date (March 2 or 3, depending on the year). This is standard date-math behavior, not a bug.
Can I calculate a date far in the past or future?
Yes, any valid calendar date works, in either direction.