Date Add/Subtract
Add or subtract from dates
Frequently Asked Questions
How do I add months to a date?
Enter a start date and the number of months to add. Adding 3 months to January 31 gives April 30 (not April 31, which does not exist). The calculator handles end-of-month edge cases correctly.
Can I subtract years from a date?
Yes. Enter a negative number or use the subtract option. Subtracting 2 years from March 1, 2025 gives March 1, 2023. For leap year dates: subtracting 1 year from February 29, 2024 gives February 28, 2023.
How does the calculator handle adding months to the 31st?
When the target month has fewer days, it adjusts to the last day. January 31 + 1 month = February 28 (or 29 in leap years). January 31 + 3 months = April 30. This follows standard date arithmetic conventions.
Can I add a combination of years, months, and days?
Yes. Enter values for years, months, and days simultaneously. The calculator adds them in order: years first, then months, then days. Adding 1 year, 2 months, and 15 days to January 1, 2025 gives March 16, 2026.
What is the difference between adding 30 days and 1 month?
Adding 30 days always adds exactly 30 calendar days. Adding 1 month moves to the same day number in the next month. From January 15: +30 days = February 14, +1 month = February 15. The difference matters for billing and contracts.