Date difference calculator.
Count days between dates, or add and subtract calendar days.
Elapsed days exclude the start date and include the end date. Identical dates give zero. Calendar days include weekends and holidays.
How this date difference calculator works
Date differences use complete calendar days. By default the start date is excluded and the end is included. Select both dates to count an inclusive interval. Adding days moves across month ends and leap years without a time-of-day adjustment.
A worked example
From 1 January 2026 to 2 January 2026 is one elapsed day, or two dates if both endpoints count. Adding 30 days to 1 January gives 31 January.
Does this calculate business days?
No. Saturdays, Sundays and public holidays are included. Business-day rules depend on the location and holiday calendar; do not use this as a working-day or legal-deadline calculation.
Calculations run on your device. Review your results before exporting or sharing them.