Add Days, Months, or Years to a Date Online — Free
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Deadlines shift, subscriptions roll over, schedules slip — and "one month from January 31" is exactly where naive math breaks. Add (or subtract) any mix of years, months, days, hours, and minutes, and get the precise resulting date. Month arithmetic clamps to real month ends: January 31 plus one month is February 28, or 29 in leap years.
How it works
- 1
Pick the starting date
Use the date-time picker — the time of day is carried through the math.
- 2
Enter the amounts to add
Years, months, days, hours, minutes — negative values subtract.
- 3
Read the resulting date
The exact date is shown in full, formatted for your locale.
About this tool
Adding time to a date, correctly
Enter a starting date and an amount — days, weeks, months, or years, positive or negative — and the tool lands on the exact result date, handling month lengths, leap years, and year boundaries. Adding a month to January 31 lands correctly on February's reality.
Days versus months are different operations
Adding 30 days is arithmetic; adding one month is a calendar operation whose result depends on the start date. Know which you mean — contracts, subscriptions, and due dates usually mean calendar months, while "30 days" language usually means days.
Subtracting is built in
Negative values move backward: subtract days to find when a deadline was set, or months to find a previous anniversary. The matching date difference tool verifies the gap between start and result.
Frequently asked questions
What happens when adding a month to January 31?
February has no 31st, so the tool lands on the last day of February — the standard calendar-aware behavior, rather than rolling into March.
Does the result account for leap years?
Yes — adding a year to February 29 lands on February 28 or 29 depending on whether the target year is a leap year.
Can I add a combination, like 3 months and 10 days?
Run it in two passes: add the months first, then add the days to the result. The order matters for month-end edge cases — months first is the convention.