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Late Finish Date

Late Finish Date (LF)

Scheduling Terms Reviewed by forProject Technology - updated Sep 2026
Quick definition: The Late Finish Date is the latest a task can finish without delaying the project, given its successor relationships — including their type and any lead or lag — and its working calendar.

Calculated during the Backward Pass, working back from the project finish. Each successor relationship imposes a limit on when the task must finish, and the earliest of those limits governs. As on the Forward Pass, the relationship type matters — a Finish-to-Start successor constrains the task's finish, while a Finish-to-Finish successor constrains it differently — and leads, lags, and the working calendar all shift the result. Tasks with little or no gap between their Early Finish Date and Late Finish Date have little float and sit close to, or on, the Critical Path.

Why it matters

The Late Finish Date defines exactly how much scheduling flexibility a task has before it starts threatening the project's finish date. It's one half of the float calculation that tells a scheduler where the real risk sits.

Also known as
N/A
Used in
Critical Path Analysis; Total Float and Free Float calculations

FAQ

How is the Late Finish Date calculated?
By working backward through the schedule from the project (or milestone) end date, following each task's dependencies.
What does it mean if a task's Early Finish Date and Late Finish Date are the same?
It means the task has zero float, which typically places it on the Critical Path.
Definition maintained by forProject Technology.
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