Finish-to-start (FS)
A finish-to-start (FS) dependency means the successor cannot start until its predecessor has finished. It is the most common dependency type and the default in most scheduling tools.
FS describes work that genuinely needs the previous output: you test what has been built, you publish what has been approved. In a predecessors column it is written as the row number alone, or with FS, so 2 and 2FS mean the same link.
Because the successor waits for the whole predecessor, an FS link passes on every day the predecessor finishes late, unless the successor had slack before it.
Worked example
| Task | Duration | Depends on | Scheduled | Total float | After the delay |
|---|---|---|---|---|---|
| 1. Write copy | 4 days | None | Days 1 to 4 | 0 days | Days 1 to 6 |
| 2. Design page | 3 days | 1 | Days 5 to 7 | 0 days | Days 7 to 9 |
The delay: Write copy takes 2 days longer.
Write copy runs days 1 to 4, so Design page starts on day 5. If the copy is 2 days late, the design starts on day 7.
Open this example in the free delay simulator to change the durations, the links or the delay and watch the schedule move.