Time tools
Date Add or Subtract Calculator
Add or subtract years, months, weeks, or days while handling leap years and month ends.
Calendar arithmetic must not treat every month as 30 days. Adding one month to January 31, 2025 constrains the result to February 28, while a leap year can produce February 29. This tool preserves calendar units and uses an explicit month-end constraint.
Time tools
Use a negative amount to subtract. Years and months retain calendar meaning, while weeks and days advance complete Gregorian dates. This works for contract dates, project milestones, and anniversaries.
Frequently asked questions
Does one month mean 30 days?
No. Months contain 28 through 31 days, so the target calendar month determines the result.
What happens when the target day does not exist?
The result is constrained to the final day of the target month instead of spilling into the next month.