What this calculator does

This date difference calculator counts the time between two calendar dates. It is useful for deadlines, project windows, travel planning and personal milestones.

Formula used

The calculator subtracts the start date from the end date to get total days, then expresses the same interval in weeks and approximate months.

How to read the result

For contracts, deadlines and official forms, check whether the end date should be included. This can change the result by one day.

Assumptions

  • Uses local calendar dates.
  • Months are shown as an approximate average for quick comparison.
  • Includes the end date only when selected.

Sources and checks

This calculator uses a standard public formula. Where rules or thresholds can change, source links are listed on the relevant page.

Frequently asked questions

Should I include the end date?

Use inclusive counting when both the first and final dates count as full days. Use exclusive counting when measuring elapsed time between dates.