SAP MRP net requirements calculation is not a simple subtraction. Planning strategies define the supply-demand model, and requirement types enforce the consumption rules. This article focuses on three core threads—strategy 20, strategy 40, and PIR consumption—to explain where gross requirements come from, how planned orders are assigned, and how the results appear in MD04. Keywords: SAP MRP, planning strategy, requirement type.
Technical Snapshot
| Parameter | Details |
|---|---|
| Domain | SAP ERP / SAP PP / MRP |
| Core Objects | Planning strategy, requirement type, requirement class, PIR, sales order |
| Common Transaction Codes | MD01, MD02, MD04, OPPS, OPPT |
| Typical Strategies | 20 (Make-to-Order), 40 (Make-to-Stock) |
| Typical Requirement Types | KE, VSE |
| Core Dependencies | Material master MRP views, strategy group, requirement class configuration |
| Data Sources | Sales orders, planned independent requirements, inventory, planned receipts |
| Article Type | Business logic analysis |
Planning strategies define the high-level framework for net requirements calculation
In SAP MRP, a planning strategy determines whether a company operates as “produce to stock before orders arrive” or “receive orders first and then produce.” This is not a presentation-layer setting. It is the entry condition for net requirements calculation.
A planning strategy controls three things: whether planned independent requirements are created, whether sales orders consume forecast, and which demand object the planned order should ultimately relate to. As a result, it directly changes the structure of gross requirements.
Planning strategies and requirement types have distinct responsibilities
A planning strategy is the higher-level rule that defines the business model. A requirement type is the execution label that identifies whether a demand comes from forecast, a customer order, or another source, and then enforces consumption behavior, availability check behavior, and settlement logic through the requirement class.
Planning strategy -> Determines the business model
Requirement type -> Identifies the demand source
Requirement class -> Defines the system execution rules
MRP run -> Calculates gross requirements, net requirements, and planning proposalsThis logic shows a clear separation: the strategy defines the rules, and the requirement type applies them.
Requirement types determine how demand enters the MRP calculation
SAP does not treat all demand equally. Different requirement types participate in net requirements calculation in different ways.
For example, VSE is commonly used for forecast demand and represents planned independent requirements, while KE is commonly used for sales order demand and represents confirmed customer pull. Their meaning in MD04 is completely different.
The generic net requirements formula must be understood together with demand consumption
Net requirements are often written as the following formula:
Net requirements = Gross requirements - Available stock - Planned receipts + Safety stockBut the key point is not the formula itself. The real question is where gross requirements come from. Gross requirements are not a fixed value. They are the result of filtering and consumption driven jointly by the planning strategy and the requirement type.
Three critical paths influence net requirements
First, the planning strategy determines whether PIRs are created before anything else. Strategy 40 typically starts with forecast, while strategy 20 is usually driven directly by sales orders.
Second, the requirement type works with the requirement class to determine whether sales orders consume forecast and what the forward and backward consumption periods are.
Third, the planned orders generated by MRP are assigned to different targets depending on the requirement type. They may be linked directly to a sales order, or they may remain unassigned as stock replenishment proposals.
DATA: lv_gross_req TYPE i VALUE 120, " Initial gross requirement: forecast demand
lv_sales TYPE i VALUE 80, " Sales order quantity
lv_stock TYPE i VALUE 30, " Current inventory
lv_net_req TYPE i.
lv_gross_req = lv_gross_req - lv_sales. " Under strategy 40: sales orders consume forecast first
lv_net_req = lv_gross_req - lv_stock. " Reduce remaining effective demand by available stock
WRITE: / 'Net Requirement:', lv_net_req. " Output net requirement = 10This code demonstrates the essential logic of strategy 40 with minimal complexity: consume forecast first, then subtract inventory.
Strategy 20 and strategy 40 represent two completely different planning philosophies
Strategy 20 is the classic Make-to-Order (MTO) model. The system treats the sales order as the primary driver, and production or procurement proposals are usually tied directly to the order object.
Strategy 40 is the classic Make-to-Stock (MTS) model. The system first creates a replenishment plan based on forecast, and when sales orders arrive later, they consume that forecast within the configured consumption window.
The difference between these two strategies maps directly to the gross requirements structure
| Comparison Item | Strategy 20 Make-to-Order | Strategy 40 Make-to-Stock |
|---|---|---|
| Demand Source | Primarily sales orders | Primarily PIRs, with sales orders consuming PIRs |
| Pre-production | Usually no | Usually yes |
| Typical Requirement Types | KE | VSE + KE |
| Gross Requirements Structure | Order demand enters directly | Forecast enters after subtracting the consumed portion |
| Planned Order Assignment | Often linked to the sales order | Often generated as unassigned planned orders |
| Business Goal | Support customization and low inventory | Balance service level and inventory efficiency |
This table serves as a quick reference for identifying the right business scenario.
A concrete example makes the net requirements calculation easier to see
Assume a material uses strategy 40. On a given day, forecast demand is 120 units, sales orders are 80 units, current inventory is 30 units, and there are no other incoming receipts.
The system does not start with 120 – 30. Instead, it first lets the 80-unit sales order consume forecast in the same period. That leaves only 40 units of effective forecast.
MD04 reveals the real structure after consumption
Material: ZFERT-001
Date Type Qty Description
2026-04-20 VSE 120 Original PIR
2026-04-20 KE -80 Sales order consuming forecast
2026-04-20 VSE 40 Remaining effective gross requirement
2026-04-20 LCH 30 Available inventory
2026-04-20 BES 10 Planned order generated by MRPThis list reflects the actual business sequence: consume first, calculate net requirements second, and generate supply proposals last.
If you switch to strategy 20, with a sales order of 100 units, inventory of 20 units, no forecast, and no incoming receipts, the net requirement is 80 units. In that case, the planned order is usually generated directly for that sales order.
Configuration determines whether the rules actually take effect in system behavior
Once you understand the concept, you still need the configuration to support it. Planning strategies are usually maintained in the material master MRP views or through the strategy group, while requirement types and their linked requirement classes are defined in backend customizing.
Transaction codes OPPS and OPPT are commonly used for requirement type and requirement class configuration. After running MRP with MD01 or MD02, you can review the result in MD04.
Use this sequence to troubleshoot unexpected results
1. Check whether the material uses the correct planning strategy
2. Check whether the expected requirement type was generated
3. Check the consumption mode and time parameters in the requirement class
4. Verify the timing relationship among stock, demand, and planned receipts in MD04This troubleshooting sequence works well for real-world questions such as: “Why did the system not generate the planned order I expected?”
Understanding net requirements from the business perspective matters more than memorizing the formula
A planning strategy is essentially SAP’s parameterized expression of how a business responds to supply and demand. A requirement type is the coded mechanism the system uses to distinguish the meaning of different demand signals. Only when these two work together does the final net requirements result emerge.
That is why net requirements are not a static number. They are a dynamic conclusion produced by the interaction of the business model, demand attributes, current inventory, and future supply. Once you understand that, you can truly interpret MRP behavior.
FAQ
FAQ 1: Why does a sales order under strategy 40 not create the full net requirement directly?
Because strategy 40 normally makes the sales order consume forecast demand first. Only the portion not covered by forecast becomes effective gross requirements and then participates in net requirements calculation.
FAQ 2: Why are planned orders sometimes linked to a sales order and sometimes not?
This depends on the planning strategy and the requirement type. In MTO scenarios, planned orders are usually created for specific orders. In MTS scenarios, planned orders are more often used for stock replenishment and are not tied to a specific customer demand at first.
FAQ 3: Which transaction code is the most important when analyzing net requirements on site?
Start with MD04. It provides a direct view of inventory, PIRs, sales orders, planned orders, and their time sequence. It is the core entry point for understanding consumption logic and the source of net requirements.
Core summary
This article explains, from both business and system perspectives, how planning strategies and requirement types affect net requirements calculation in SAP MRP. It highlights the differences between strategy 20 and strategy 40 in terms of gross requirements sources, forecast consumption, planned order assignment, and MD04 visibility, and it provides configuration entry points and practical diagnostic methods.