# How to calculate a project end date from a duration in working days in Excel

Count the duration minus one working day from the start: `=WORKDAY(B2,C2-1,holidays)`, so the start day counts as day 1.

**Excel:** `=WORKDAY(B2,C2-1,$F$2:$F$3)` (Every current version)

**Google Sheets:** the same formula works.

## Example

Sample data (row 1 is the header):

| A | B | C | D | E | F |
| --- | --- | --- | --- | --- | --- |
| Task | Start | Duration (working days) | End |  | Holidays |
| Design | 2026-05-04 | 10 |  |  | 2026-05-25 |
| Build | 2026-05-18 | 15 |  |  | 2026-07-03 |
| Test | 2026-06-22 | 10 |  |  |  |
| Launch | 2026-07-07 | 2 |  |  |  |
| Review | 2026-07-13 | 5 |  |  |  |

Formula in D2, filled to D6: `=WORKDAY(B2,C2-1,$F$2:$F$3)`

Result: 5/15/2026; 6/8/2026; 7/6/2026; 7/8/2026; 7/17/2026

## 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.

## Other ways

- `=WORKDAY(B2,C2,$F$2:$F$3)`: 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.

## 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.

Every formula and result on this page was checked by running it in the Spreadsheet Practice formula engine on 2026-10-30.

Source: https://spreadsheetpractice.com/formulas/project-end-date-from-working-days