Online
Pick the two dates in Days Between Dates. It shows the total days, weeks and days, years, months and days, and weekdays (Monday to Friday). Tick Include end date if both the first and last day should count, as for a hotel stay counted in days rather than nights.
In Excel or Google Sheets
With the start date in A1 and the end date in B1:
- Days:
=B1-A1(format the cell as a number, not a date). - Weekdays, counting both ends:
=NETWORKDAYS(A1,B1). Add a range of holiday dates as a third argument to skip them too. - Whole months or years:
=DATEDIF(A1,B1,"m")or=DATEDIF(A1,B1,"y").
Counting forwards instead
To find the date 90 days or 30 business days from today, use Add or Subtract Days. In a spreadsheet, =A1+90 adds calendar days and =WORKDAY(A1,30) adds working days.
Common mistakes
- Off by one: from Monday to Friday is 4 days apart but 5 days if you count both.
- Months are not all the same length: "one month" from 31 January lands on the last day of February.