Add Days to a Date Calculator

How to use this calculator

Choose a start date (today by default) and the number of days to add. Use a negative number to go back in time. The resulting date is shown with its day of the week.

Common uses

• Deadlines: “within 30 days of the invoice date”
• Notice periods: 60 or 90 days
• Medication or treatment courses
• Warranty and return windows

Weeks and months

To add weeks, multiply by 7 (6 weeks = 42 days). Months have different lengths, so “3 months” is not always 90 days — check the exact date your contract means.

Frequently asked questions

What date is 90 days from today?

Leave the start date as today and enter 90 — the resulting date and weekday are shown.

How do I subtract days?

Enter a negative number, such as −30.

Can I find how many days are between two dates here?

Yes — press × on Days and set both dates. Or use the days between dates calculator.

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