Calculate days, weeks, months and business days between two dates
To find the number of days between two dates, subtract the earlier date from the later date. Each full day counts as one. For example, from 1 January to 31 January is 30 days.
Business days are weekdays only (Monday to Friday), excluding weekends. They do not automatically exclude public holidays — for that you would need to account for the specific holiday calendar of your state.
A standard year has 52 weeks and 1 day (365 days ÷ 7). A leap year has 52 weeks and 2 days. This is why the same calendar date falls on a different day of the week each year.
Months between dates are approximated as total days ÷ 30.44 (the average number of days per month). For exact month counting, you need to account for the varying number of days in each month.
Common uses: calculating project timelines, working out how many days until an event, figuring out if a contract notice period has been met, calculating age or how long something has been running.