purr.tools

Date Calculator

Find the difference between two dates in years, months, and days, or calculate a future/past date by adding or subtracting days.

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How to use the date calculator

Choose 'Date Difference' to find the gap between two dates, or 'Add/Subtract Days' to find a date after a number of days. In difference mode, the years/months/days breakdown uses exact calendar math.

How date differences are calculated

The breakdown into years, months, and days is computed by calendar arithmetic: full years first, then remaining months, then remaining days. The total days count is the absolute number of days between the two dates.

FAQ

How are months calculated?

The calculation subtracts full calendar months, borrowing days from the previous month when needed -- the same way you count age in years and months.

Can I calculate a past date?

Yes -- enter a negative number in the Days to Add field (e.g. -30) to get a date 30 days in the past.

Embed this tool

Add this tool to your website by copying the snippet below.

<iframe
  src="https://purr.tools/en/embed/date-calculator"
  width="100%"
  height="500"
  style="border:0;border-radius:8px;"
  loading="lazy"
  title="Date Calculator -- Free Online Tool"
  allow="clipboard-write"
></iframe>