Date Calculator

Two things this does

Between two dates — how many days, weeks and months separate them. Useful for notice periods, project durations, and how long something has been outstanding.

Add or subtract days — take a date, move forward or backward by a number of days, and see where you land. This is how you find a deadline: thirty days from an invoice, ninety days from a joining date, a fortnight before an exam.

Why counting by hand goes wrong

Month lengths are irregular and February changes. "Three months from 30 November" has no obvious answer, and "90 days" and "3 months" are different spans that people routinely treat as the same thing. Contracts are usually written in days precisely because days are unambiguous.

The calculation here walks the real calendar, so leap years and short months are handled without you having to think about them.

Common uses

• Notice periods — the exact last working day, not an approximate one.
• Payment terms — when a net-30 or net-45 invoice actually falls due.
• Deadlines — filing windows, appeal periods, statutory limits.
• Planning — days remaining until an exam, a wedding, or a launch.

Frequently Asked Questions

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