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Schedulingaka: LSaka: LFaka: late dates

Late Start / Late Finish

In Plain English

The latest possible dates an activity can start and finish without pushing back the project completion date.

Definition

Late Start (LS) and Late Finish (LF) are backward-pass CPM calculations that determine the latest possible date an activity can begin and still allow the project to complete on time. LS and LF define the outer boundary of the scheduling window for each activity. The difference between late dates and early dates equals total float for that activity.

Why It Matters in Bidding

Late dates define how much an activity can slip before it threatens the contract completion date, so they are the backbone of float calculation and critical-path identification that estimators rely on to sequence subs and stage cash flow. Understanding late dates also strengthens a contractor's position in delay claims, since they prove which activities had no slack when an owner-caused disruption hit.

Example

A scheduler reads an activity's late finish to confirm a long-lead steel package can still be ordered two weeks later without delaying the project's substantial completion.

Related Terms

Early Start / Early FinishFloatCritical Path Method (CPM)Predecessor

Frequently Asked Questions

They come from the backward pass through the network. Starting at the project finish date, the scheduler subtracts each activity's duration moving from successors to predecessors. Late finish is the latest an activity can end without delaying the project; late start equals late finish minus the activity's duration.
Total float equals late start minus early start, which also equals late finish minus early finish. When that difference is zero, the activity has no slack and sits on the critical path. Tracking late dates therefore tells estimators and schedulers exactly which work cannot slip without extending the contract.
Late dates show the latest a sub can mobilize without causing a project delay, giving the GC room to coordinate crews, deliveries, and inspections. They also help defend against backcharges, because a sub that finishes within its late dates has not delayed the job even if it missed its early-date target.

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