Excel dates and times: calculations that don't break
For office, HR, finance and operations staff who work out deadlines, notice periods, lengths of service, working days or shift hours in Excel. Prerequisite: 'Spreadsheet fundamentals for office work' (cell references, simple formulas, number formats). If your dates arrive as text from another system, take 'Spreadsheet data cleaning' first. You'll learn how Excel stores dates and times, why a workbook can be four years out, and how to use subtraction, DATEDIF, NETWORKDAYS, NETWORKDAYS.INTL, WORKDAY, EDATE, EOMONTH, DATE and time formats so results stay right when the file is reopened, copied or shared. Based on Microsoft's Excel documentation; menus differ slightly between Windows, Mac and the web. Your organisation's holiday calendar and working week apply.
- Level
- Intermediate
- Length
- About 95 minutes
- Contents
- 5 lessons · final exam
- Status
- Published · updated 10 Oct 2026
Skills you'll practise
- Identify how Excel stores a date or time as a serial number, and recognise a workbook that uses the 1904 date system
- Calculate days, complete months and complete years between two dates with subtraction and DATEDIF, without the unreliable "MD" unit
- Calculate working days and working-day deadlines with NETWORKDAYS, NETWORKDAYS.INTL and WORKDAY using a holiday list
- Calculate month-based due dates with EDATE and EOMONTH, and build dates with DATE instead of typed text
- Calculate elapsed time across midnight and beyond 24 hours using full date-times and the [h]:mm format
Course outline
- 1.Identifying how Excel stores dates and timesLesson · 14 min
- 2.Calculating days, months and years between datesLesson · 15 min
- 3.Calculating working days and deadlines with a holiday listLesson · 16 min
- 4.Calculating month-based due dates with EDATE, EOMONTH and DATELesson · 13 min
- 5.Calculating elapsed time across midnight and beyond 24 hoursLesson · 14 min
- 6.Excel dates and times: calculations that don't break: knowledge checkKnowledge check · 15 questions
- 7.Excel dates and times: calculations that don't break: practical exerciseKnowledge check · 1 question
- 8.Final exam10 questions · passing it completes the course, so people who already know the material can test out
Sources it draws on
The lessons and questions are written from these references, so learners can go back to the original.
- Microsoft Support: Date systems in Excel (1900 and 1904 date systems)
- Microsoft Support: DATEDIF function
- Microsoft Support: Calculate the difference between two dates
- Microsoft Support: NETWORKDAYS function
- Microsoft Support: NETWORKDAYS.INTL function
- Microsoft Support: WORKDAY function
- Microsoft Support: EDATE function
- Microsoft Support: EOMONTH function
- Microsoft Support: DATE function
- Microsoft Support: TODAY function
- Microsoft Support: TIME function
- Microsoft Support: Calculate the difference between two times in Excel
- Microsoft Support: Format numbers as dates or times
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