Date & Time Calculator
Date Add / Subtract Calculator
Add or subtract years, months, weeks, and days from a date.
⚠️ Please select a date and enter valid non-negative values.
New Date
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Calculator guide
How this calculator works
How to use this calculator
Select a start date, choose add or subtract, enter years, months, weeks, and days, then calculate the new date.
Formula used
The calculator changes the selected date by adding or subtracting the chosen calendar units. Weeks are converted to 7 days. Months are handled as calendar months, so results can vary depending on the starting day of the month.
Example calculation
Adding 30 days to January 1, 2026 gives January 31, 2026.
What the result means
The result is the calendar date after adding or subtracting the selected time period.
Frequently asked questions
Are months treated as 30 days?
No. Months are treated as calendar months.
Can I subtract time from a date?
Yes. Choose Subtract time from the operation menu.
Can I add weeks and days together?
Yes. Weeks are converted into days and included in the final calculation.