Dates & time
Work with real dates, month boundaries and explicit working calendars.
By the end, you’ll be able to:
- Build dates without ambiguous date-text formats
- Use month ends and date parts
- Count inclusive weekdays and represent elapsed time
A date is a value with a display format
Excel ordinarily stores dates as serial numbers and times as fractions of a day. Formatting changes their display, not the stored instant. A date-looking text string may not behave as a date.
Use unambiguous construction for an international workbook. The text 03/04/2026 can mean different dates in different locales, while =DATE(2026,4,3) explicitly means 3 April 2026. The tasks below use the standard 1900 date system and fixed dates so results do not change overnight.
| A | B | C | D | E | |
|---|---|---|---|---|---|
| 1 | Year | Month | Day | Hours | Minutes |
| 2 | 2026 | 10 | 16 | 9 | 30 |
| 3 | 2026 | 10 | 19 | 17 | 0 |
Build and inspect a date
=DATE(year, month, day)=YEAR(serial_number)=MONTH(serial_number)=DAY(serial_number)=TODAY()year, month and day define a date; use four-digit years. The date-part functions take one date serial and return its calendar component. TODAY takes no arguments and returns the current date when recalculated.
=DATE(A2,B2,C2) is 16 October 2026, serial 46311 in the 1900 system. YEAR returns 2026, MONTH returns 10 and DAY returns 16. DATE can roll out-of-range months or days, so it is not by itself a strict input-validation test.
Calculate the end of a month
=EOMONTH(start_date, months)start_date is a real date or date-producing expression. months is the month offset: 0 for that month, 1 for the next, -1 for the previous.
=EOMONTH(DATE(2026,10,16),0) is 31 October 2026. Adding 1 gives the first day of November. A boundary constructed from month ends is more reliable than assuming every month has 30 days. Apply a date format if Excel displays the returned serial number.
State which days count as working days
=NETWORKDAYS(start_date, end_date, [holidays])start_date and end_date define an inclusive interval. Optional holidays is a range of real dates to exclude. Standard NETWORKDAYS excludes Saturdays and Sundays; use NETWORKDAYS.INTL in Excel for another weekend pattern.
Friday 16 October 2026 through Monday 19 October 2026 contains 2 working days when no holidays are supplied. If Monday is a holiday in your chosen calendar, supplying that holiday reduces the count to 1. Do not assume a single country’s holidays apply internationally.
Separate time of day from elapsed duration
Nine hours and thirty minutes is =9/24+30/1440, or 0.3958333333 of a day. Format it as a time to show 09:30. Subtracting two genuine date-time values gives elapsed days; multiply by 24 for decimal hours.
A duration can exceed 24 hours. In Excel, an elapsed format such as [h]:mm preserves accumulated hours, while an ordinary time-of-day format can wrap. These date functions work across established Excel editions and current web Excel. The practice checker uses fixed modern dates rather than Excel’s historical 1900 leap-year edge case.
Give it a try.
Work through each exercise, check your answer and use a hint whenever you need one. Formula tasks check changed inputs, including boundary cases.
0 of 5 exercises complete
The bounded practice checker accepts equivalent supported formulas, lowercase function names and text labels, extra spaces, and comma or semicolon separators. Array tasks check the complete result shape and values. It is a teaching tool, not a complete Excel engine. See supported behavior.
Take this with you
Use real dates, explicit date construction and a defined working calendar. Format dates and durations according to what they mean.
Practice in Excel
Download the course workbook, follow the tasks, save your completed .xlsx and check its supported formula tasks here. Native Excel features use a separate review checklist.
Download practice workbook Check my workbook ↗Technical references and lesson review
Original lesson content. Technical behavior checked against Microsoft documentation. Reviewed 2026-10-16.