Free · Instant calculations
Date Addition Calculator
Add or subtract days, weeks, months and years from a date.
How to use this tool
Choose the calculation method, enter your values and select Calculate. Reset clears results and restores the example inputs.
Formula
Add calendar months or years first when selected; days and weeks use exact calendar-day offsets.
Example
31 January 2026 plus one month is 28 February 2026.
Assumptions and limits
A month-end result clamps to the final valid day. Enter a whole signed amount.
Frequently asked question
Why does 31 January become 28 February? February has no 31st day, so the result uses its last day.