Date Calculator | Difference, Add or Subtract Dates

Find total days and calendar years, months, and days between dates, or add and subtract signed years, months, weeks, and days.

Focus mode

Date calculator

Compare two dates or apply signed duration fields to a starting date.

First date

Second date

Include end date

Counts the later date as one day and updates both totals and the calendar breakdown.

The second date is later.

Total days: 29 Days
Calendar difference: 0 Years · 0 Months · 29 Days

Fields apply in years → months → weeks → days order. A missing day in the target month is clamped to that month's last day.

Key features

Shows both total days and completed calendar years, months, and days between two dates.
Makes end-date inclusion optional and identifies dates entered in reverse order.
Adds or subtracts signed year, month, week, and day fields from a starting date in a stated order.
Uses UTC day ordinals for date-only arithmetic so daylight-saving changes cannot shift the result.

How to use

Choose Date difference or Add/subtract date.
Enter two dates, or a starting date and signed duration fields.
Review total days, the calendar breakdown, or the resulting date and any month-end adjustment.

Examples

Measure a contract or project period
Compare the total day count with a calendar years-months-days breakdown for a start and end date.
Find a scheduled date from a baseline
Apply mixed positive or negative fields such as three months and two weeks to a known date.

Privacy

Dates and results are processed only in the current browser and are never sent to or stored on a server.

Requirements

Uses Gregorian calendar dates. Fields apply in years → months → weeks → days order; a missing day in the target month is clamped to that month's last day.

Common questions

What changes when I include the end date?: The later endpoint is treated as one day later, so equal dates become one day and both total days and the calendar breakdown change together.
What happens when I add one month to January 31?: Because February has no 31st, the result clamps to February 29 in a leap year or February 28 otherwise and reports the adjustment.