How to calculate a project end date from a duration in working days in Excel
Formula (Excel and Google Sheets)
=WORKDAY(B2,C2-1,$F$2:$F$3)Count the duration minus one working day from the start: =WORKDAY(B2,C2-1,holidays), so the start day counts as day 1.
- Result on the example
- one result per row in
D2, filled down toD6 - Works in
- Every current version
- Google Sheets
- Same formula
See it work
The formula is already in D2, filled down to D6. Change any input and the result updates, or edit the formula to experiment.
How it works
A task that starts on a working day and lasts 10 working days ends 9 working days later, so the formula adds C2-1. WORKDAY skips weekends and the holidays in F2:F3: the Build task runs over Memorial Day and ends a day later because of it.
=WORKDAY(B2,C2-1,$F$2:$F$3)Result5/15/2026 (46157)
B25/4/2026The value in B2.
C210The value in C2.
C2-19The - operator subtracts.
$F$2:$F$32 rows × 1 col: 5/25/2026, 7/3/2026A range: 2 cells in one column.
WORKDAY(B2,C2-1,$F$2:$F$3)5/15/2026 (46157)WORKDAY: Date a number of workdays away.- start_date
B25/4/2026 - days
C2-19 - holidays
$F$2:$F$32 rows × 1 col: 5/25/2026, 7/3/2026
- start_date
In Google Sheets
The same formula works in Google Sheets: =WORKDAY(B2,C2-1,$F$2:$F$3). We ran it in Google Sheets mode on the same data and it returns the same results.
Other ways to do it
Each one was run on the same example sheet.
| Formula | Result | When to use it |
|---|---|---|
| =WORKDAY(B2,C2,$F$2:$F$3) | 5/18/2026, 6/9/2026, 7/7/2026…Different result | Counts the whole duration after the start day. One working day later. |
Common mistakes
=WORKDAY(B2,C2)doesn't count the start day, so every task ends a day late.- A start date on a weekend still counts as day 1. Move starts to a weekday first.
Try it yourself
Same data, empty answer cell. Your formula is graded instantly, then re-checked on changed data, so a typed-in number won't pass.
Calculate a project end date from a duration in working days
D2, calculate the last working day of each task, counting the start date as day 1 and skipping weekends and the holidays in F2:F3. Fill down to D6.Questions
How do I calculate the duration from start and end dates?
=NETWORKDAYS(B2,D2,$F$2:$F$3) counts both ends.
How do I start the next task the day after?
=WORKDAY(D2,1,$F$2:$F$3) returns the next working day.
Checked by running on 2026-10-30: every formula and result on this page was calculated by the Spreadsheet Practice formula engine, in both Excel and Google Sheets modes.