Do not add parallel task durations to predict earliest completion.
Which tasks are sequential and which can overlap in the supplied dependency model?
Use the matching calculator
Use this decision sequence
- List tasks in an order where predecessors appear before dependants.
- Use zero predecessor for independent tasks and an earlier task number for one dependency.
- Calculate each finish from its predecessor’s finish plus entered duration.
- Compare the longest finish with total effort, while keeping resource feasibility outside this simple model.
Keep the quantities distinct
| Quantity or assumption | How to use it |
|---|---|
| Summed durations | Total entered task effort. |
| Dependency completion | Longest finish across task chains. |
| Resource constraint | Not represented by one predecessor and unlimited parallel resources. |
Worked comparison
An illustrative task A lasts three hours, B lasts four hours after A, and C lasts five hours independently. Entered durations sum to 12 hours, but the unconstrained earliest completion is max(3+4,5) = 7 hours. If the same worker must do every task, the seven-hour bound is not a feasible crew schedule; extra resource constraints are needed.
Check before using the estimate
The result is an unconstrained planning bound, not a staffing recommendation or delivery promise.
All dimensions, product properties, prices and specifications in this example are illustrative arithmetic inputs. Use the values from your measured plan, selected product data sheet and supplier quote. This guide does not choose construction specifications or certify safety.
Calculation and scope checked 2026-10-04. Methods and scope.