Marks Calc
Number tool

Date Difference Converter

Calculate the difference between any two dates — in days, weeks, months, years, hours and minutes. Optionally exclude weekends. Used for age calculations, project deadlines and visa overstay checks.

How the conversion works

Days between are computed as `Math.round((dateB - dateA) / 86_400_000)` after normalising both dates to UTC midnight to avoid DST drift. Calendar-aware months/years use the actual day-of-month and month-of-year, not 30.4-day or 365.25-day approximations.

When you'll use this converter

  • How old am I in days / weeks?
  • How many days until my exam / wedding / vacation?
  • Visa overstay calculations
  • Project deadlines and contract durations
  • Pregnancy / due-date tracking

Frequently asked

Are start and end dates both counted?

By default we count the difference (end − start). For an inclusive count (e.g. "how many days am I on holiday" where both bookend days count), add 1 to the result.

How do you handle leap years?

Native JavaScript Date arithmetic handles leap years automatically — Feb 29 in leap years adds one extra day to the count.

Can I exclude weekends?

Yes — toggle the "Exclude weekends" option to count only Mon–Fri (useful for working-day estimates and SLA calculations).