Example 1
- 01/31/2024
- 0 years
- 1 month
- 0 weeks
- 0 days
02/29/2024
What date is January 31, 2024 plus 1 month? February 29, 2024.
Add Years and Months to a Date
The calculator adds years, months, weeks, and days to one date. January 31, 2024, plus 1 month is February 29. This is not the page that adds days only.
Days only are on the date calculator. The span between two dates is on date difference.
Result
Enter a date and the spans. The result will appear here.
How it works
The calculator adds years and months first, clamps the day to the last day of the month, then adds weeks and days. January 31, 2024 plus 1 month is February 29, 2024.
January 31, 2023 plus 1 month is February 28, 2023, because that February has 28 days.
January 1, 2024 plus 1 year, 1 month, 1 week, and 1 day is February 9, 2025.
February 29, 2024 plus 1 year is February 28, 2025, because 2025 is not a leap year.
This is not the same page that adds days only. That page uses a day count only. The difference of two dates is on a separate page.
Empty fields are zero. A negative number moves the calendar back. The calculator does not accept a fraction.
Formula
date′ = clamp(date + years + months) + 7×weeks + days
clamp keeps the last day of the month when the start day does not exist, for example January 31 plus 1 month.
How to use
- In the start date choose January 31, 2024.
- In months enter 1. Leave years, weeks, and days empty.
- Calculate. The result is February 29, 2024.
- To get February 9, 2025, set January 1, 2024 and 1, 1, 1, and 1.
February 29 from January 31 plus 1 month
Month-end is clamped. Without that, January 31 plus 1 month would spill into March 2 or 3.
- 29.02.2024
- January 31, 2024 plus 1 month, a leap year.
- 28.02.2023
- January 31, 2023 plus 1 month, a common year.
- 09.02.2025
- January 1, 2024 plus a year, month, week, and day.
Examples
Example 2
- 01/31/2023
- 0 years
- 1 month
02/28/2023
What date is January 31, 2023 plus 1 month? February 28, 2023.
Example 3
- 01/01/2024
- 1 year
- 1 month
- 1 week
- 1 day
02/09/2025
What date is January 1, 2024 plus a year, month, week, and day? February 9, 2025.
Related calculators
Frequently asked questions
What date is January 31, 2024 plus 1 month?
February 29, 2024. February 2024 has 29 days, so day 31 is clamped to 29.
What date is January 31, 2023 plus 1 month?
February 28, 2023. February 2023 has 28 days.
What date is January 1, 2024 plus 1 year, 1 month, 1 week, and 1 day?
February 9, 2025. Year and month first give February 1, 2025, then 8 days.
Is this the same date calculator that adds days only?
No. That page uses a day count only. Here years, months, weeks, and days are in one form.
Is February 29, 2024 plus 1 year February 29, 2025?
No. 2025 is not a leap year, so the result is February 28, 2025.
Do negative numbers move the date back?
Yes. −1 month from January 1, 2024 is December 1, 2023.
What comes first, months or days?
Years and months first, with month-end clamping, then weeks and days.
Is this the difference between two dates?
No. Date difference is on a separate page. Here you add spans to one date.
Are empty fields zero?
Yes. Empty years, months, weeks, or days count as 0.
Can I enter a fraction of a month?
No. Years, months, weeks, and days must be whole numbers.
Sources
Adding months clamps the month-end. This is not a shift by a fixed 30 or 31 days.
Page updated in 2026.