Aggregate planning is the tactical level of planning: it translates leadership's direction into volumes by product family, over a horizon of several months to about eighteen months. The resulting aggregate production plan is the supply-side output of S&OP, and it feeds the master production schedule. Sitting between the big picture and shop-floor detail, it answers a simple but decisive question: given expected demand, what must we produce, source, and stock, by product family, to maintain service without inflating inventory?
Aggregate planning between S&OP and the master schedule
Aggregate planning belongs to a three-tier planning chain. At the top, the decision process, S&OP, aligns leadership on a single plan; our article What Is S&OP? explains the logic. Aggregate planning is the tactical link: it works by product family, not by item, and settles the major balances between demand and capacity. Its output, the aggregate production plan, is the supply side of the S&OP plan. Below it comes the master production schedule (MPS), which breaks the plan down to finished products and weeks. Aggregate planning is therefore the bridge between strategic decisions and detailed execution. This planning chain is what we work on in our S&OP consulting engagements.
How to build an aggregate plan, step by step
Building an aggregate plan follows a consistent logic. You start from the aggregate demand forecast by family. You compare it with available capacity: production, sourcing, and resources. You simulate scenarios using the usual levers (building stock ahead, overtime, subcontracting, workforce changes, backlog) and quantify their consequences. Then you decide: leadership approves a plan by family, which becomes the reference for the MPS. Aggregate planning doesn't seek item-level precision; it seeks the right overall balance, the one that avoids both stockouts and overstock at the family level.
When does an SME need it?
An SME benefits from a formal aggregate plan as soon as its capacity decisions (hiring, subcontracting, building seasonal stock) can no longer be made on instinct. This is especially true with strong seasonality or long lead times, where decisions must be made months ahead. Aggregate planning is a clear illustration of the Two-Layer Model: it belongs to the decision layer (the major trade-offs approved by leadership), while the MPS and scheduling belong to the execution layer that carries them out.
The common mistake
The most frequent mistake is skipping the tactical level: jumping straight from strategy to production detail, with no aggregate plan. Capacity trade-offs are then made in a rush, item by item, with no overall view. The other trap is building the aggregate plan at item level: it becomes heavy, unreadable, and duplicates the MPS. Aggregate planning must stay at the right level of detail, the product family, to fulfill its steering role.
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Frequently asked questions
What is aggregate planning?
It is the tactical level of planning, translating strategy into volumes by product family over several months to about eighteen months, between S&OP and the master schedule.
What is the difference between aggregate planning and the master schedule?
Aggregate planning works by product family and settles the major balances; the master schedule breaks the plan down to finished products and weeks for execution.
Does an SME need aggregate planning?
Yes, as soon as capacity decisions must be made months ahead, notably with seasonality or long sourcing lead times.