MRP
Quick facts
| Category | Automated material and production planning calculation |
|---|---|
| Used by | Manufacturing, medical devices, pharmaceuticals, aerospace, automotive and other production-based industries |
| Also called | MRP |
| Related standards | None specific |
| Related processes | Bill of materials, demand forecasting, purchasing software, work order management |
| Semantic match | MRP, material requirements planning, MRP vs ERP, BOM explosion |
What is MRP?
MRP calculates exactly what materials are needed, in what quantities, and by what date, to meet planned production. It does this by combining three core inputs: a demand signal, such as a sales order or forecast; a product's bill of materials, defining what components go into it; and current inventory levels, showing what is already on hand.
Using these inputs, MRP works backward from a required completion date, accounting for lead times at each level of a product's structure, to determine when purchase orders or production work orders need to be initiated to meet that date without excess inventory building up along the way.
MRP was among the earliest categories of business software developed for manufacturing, tracing back to the 1960s. As its scope expanded to include broader manufacturing resources like capacity and labor, it evolved into MRP II, and eventually into the modern ERP systems that now typically include MRP as one core planning module.
Why is MRP important?
Without MRP, material planning often relies on manual estimation or reactive ordering, increasing the risk of both production delays from shortages and excess inventory from over-ordering.
By calculating requirements based on actual demand, bills of materials and current stock, MRP reduces the guesswork involved in purchasing and production scheduling, improving both on-time delivery and working capital efficiency.
MRP's calculations become increasingly valuable as product complexity grows, particularly for multi-level bills of materials where manual calculation of requirements across every subassembly would be impractical.
How does MRP work?
A typical MRP process includes:
- Demand input. Gather sales orders and, where applicable, forecasted demand.
- BOM explosion. Break down the demand into required components using the bill of materials.
- Inventory netting. Subtract available inventory and open orders from gross requirements.
- Lead time offsetting. Calculate when orders need to be placed based on lead times.
- Order recommendations. Generate suggested purchase orders and work orders.
- Review and release. Planners review and release recommended orders as actual purchase and work orders.
MRP vs. ERP
| Comparison | MRP | ERP |
|---|---|---|
| Scope | Material and production planning specifically | Entire business, including finance, sales and HR |
| Origin | Developed in manufacturing during the 1960s | Evolved from MRP II in the early 1990s |
Real-world examples of MRP
A manufacturer's MRP system calculates that a customer order due in six weeks requires a component with an eight-week supplier lead time, immediately flagging the need to expedite or find an alternate source.
An electronics company relies on MRP to explode a multi-level bill of materials for a complex assembly, automatically calculating requirements at every subassembly level rather than requiring manual calculation for each one.
A contract manufacturer uses MRP-generated purchase order recommendations, reviewing and releasing them each morning rather than manually determining what to order from scratch.
Regulations and standards related to MRP
MRP is not itself a regulatory requirement, though accurate material planning supports broader supply chain reliability that regulated manufacturers depend on to avoid production disruptions affecting customer commitments.
How QT9 helps with MRP
QT9 MRP capabilities
- Calculate material requirements automatically from demand, BOM and inventory data.
- Generate purchase order and work order recommendations based on real-time needs.
- Explode multi-level bills of materials for complex assemblies.
- Connect material planning directly to purchasing and production scheduling.
- Reduce excess inventory and prevent unexpected shortages.
- Integrate seamlessly with QT9 QMS for connected quality and operations data.
See QT9 Software in Action
Discover how QT9 Software helps manufacturers improve efficiency, strengthen compliance and connect quality management and ERP processes within one integrated platform.
Common mistakes with MRP
Common mistakes include running MRP with inaccurate inventory or bill of materials data, producing purchase and work order recommendations that do not reflect true material needs.
Other problems include ignoring or overriding MRP recommendations so frequently that the system's calculations become disconnected from actual purchasing practice, undermining its planning value.
Frequently asked questions
Related quality management terms
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