Calendar-exact difference between two dates with honest borrowing math

How to use

1. Pick both dates (birthdays, anniversaries, any events).
2. Read the exact Y/M/D difference and total days.
3. Order is handled for you — the older date is detected automatically.

About this tool

Two and a half years apart hides real information — this calculator gives the exact calendar difference between two birth dates (or any two event dates): precise years, months and days with proper month-length borrowing, plus total days and a weeks-and-days breakdown. Perfect for siblings, anniversary planning, contract dates, pregnancy milestones or sports age brackets. It handles leap years and 31-day months through real date arithmetic, not 30-day shortcuts, and swaps the dates automatically so the answer reads naturally. All the math runs in your browser — the dates you enter are never sent anywhere. Everything runs locally in your browser — nothing is uploaded, nothing is sent to any server, and closing the tab erases it all.

FAQ

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