Home › Date & Time Calculators › Add or Subtract Days Calculator
Add or subtract days, weeks, months or years from any date.
How the calculation works
Pick a start date, choose to add or subtract, then enter an amount and a unit. The calculator returns the resulting date with the day of the week.
Formula used
New date = start date ± amount × unit
Example
45 days after 13 October 2026 is Friday, 27 November 2026.
Frequently asked questions
What happens at month ends?
Adding months to a date like 31 January rolls to the nearest valid date in the target month.
Can I enter a negative number?
Use the Subtract option instead.
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Results are estimates for general information only and are not professional financial, medical or legal advice.