What Is Earliest Due Date (EDD) Scheduling?

Earliest due date, abbreviated EDD, is a priority rule that sequences jobs so the one with the soonest deadline runs first. It is the scheduling equivalent of tackling your assignments in the order they are due. EDD is simple, predictable, and aimed squarely at on-time delivery, which is why it is one of the first dispatching rules any scheduler learns, and it is one of the sort strategies EDGEBIC can apply when it orders a queue of jobs.

This entry is part of the EDGEBIC by User Solutions glossary series; for the broader vocabulary of planning, see the manufacturing glossary.

How Earliest Due Date Works

EDD takes the full set of jobs waiting for capacity and sorts them by due date, soonest first. The scheduler then places them in that order. When two jobs carry the same due date, a secondary key breaks the tie: in EDGEBIC that secondary key is job priority, so a high-priority order beats a routine one sharing the same deadline.

The appeal of EDD is that it maps directly to the goal most shops care about, which is shipping on time. If you always work on whatever is due next, you never leave an urgent order sitting while you polish a job with weeks of runway. The rule is also cheap to compute and easy to explain to the floor, which matters when a supervisor has to trust the printed sequence.

The limitation is that EDD is blind to workload. It sees only the date, not the hours of work still ahead. Two jobs due the same Friday look identical to EDD even if one needs two hours and the other needs thirty. The thirty-hour job is in far more danger, but EDD has no way to know that. This is precisely the gap that critical ratio fills by dividing time remaining by work remaining.

A Concrete Example

Four jobs sit in a single machine queue on Monday:

EDD sequences them A, B, C, D. Job A runs first because Wednesday is the soonest deadline. Jobs B and C both fall on Thursday, so the tie breaks on priority and B, the high-priority order, runs ahead of C. Job D, due Friday, runs last.

Notice EDD never asked how long any job takes. If Job D happened to need forty hours and the others two hours each, EDD would still run it last, and it might miss Friday. Whether that is the right call depends on how evenly the work is spread, which is why EDGEBIC does not stop at a single rule.

How EDGEBIC Uses It

EDGEBIC's scheduling engine already leans on due dates in its baseline order, which sorts jobs by start time and then by due date. On top of that, the multi-run schedule optimizer treats EDD as one explicit ordering heuristic, described as due date then priority.

When the optimizer runs, it generates a complete finite-capacity schedule for each candidate ordering, including EDD, critical ratio, shortest and longest processing time, priority-then-due-date, and seeded shuffles. Every schedule is scored against your goals, and the optimizer keeps the best result. A never-worse clamp guarantees the chosen plan is never inferior to the engine's default greedy schedule.

That design means EDD is a proposal, not a decree. The engine adopts the EDD sequence only when the full schedule it produces, with real shift capacity and setup times applied, actually delivers the best outcome. Because ordering and capacity interact, a rule that looks ideal on a whiteboard can lose once shared machines and shift boundaries are in play, and the comparison decides. See how the presets steer the objective in the optimizer goals and presets guide, and how modes trigger a run in the scheduling modes guide.

Related Reading

EDD is the date-only member of the dispatching family; see critical ratio for the version that also weighs remaining work, and the generic priority rules glossary for the wider set. For the difference between scheduling from the start versus from the deadline, read forward versus backward scheduling.