Date Calculator
Pick a date, choose to add or subtract, and we'll tell you the resulting date and weekday.
Inputs
Result
Result date
Friday, September 11, 2026
2026-09-11 · Friday
Next useful calculators
Visual breakdown
Start
2026-08-12
Change
+30 days
Result
2026-09-11
Weekday
Friday
Formula
Days/weeks shift the timestamp by 86,400 s × N. Months/years use real calendar arithmetic — month-end dates are clamped to the next month's last day.
Example
1 Jan 2026 + 30 days = 31 Jan 2026 (Saturday).
Common examples
Today + 30 days
Useful for invoice or notice periods.
Today + 6 months
Plan a contract end date.
Today − 14 days
Look back two weeks.
Frequently asked
What about month-end edge cases?
Adding 1 month to 31 Jan rolls forward, so February's last day is used (28 or 29). This matches most calendar apps.
Are leap years handled?
Yes — adding years to 29 Feb in a leap year lands on 28 Feb in non-leap years.
Can I subtract a date instead?
For days between two dates, use the Date Difference Calculator.