MRP and ERP get used as if they were rival products, and manufacturers shopping for software are often asked to pick one. They are not alternatives. MRP is a planning method that answers one question: what do we need to buy and make, how much, and when. ERP is the system of record for the whole business, and a manufacturing ERP contains MRP as one of its engines. The real decision is whether a standalone MRP tool is still enough, or whether planning needs to sit inside the same system as orders, inventory and the books. This post explains the difference, where each fits, and the signs a manufacturer has outgrown standalone MRP.
What MRP does
Material requirements planning takes three inputs and produces one output. The inputs are demand (sales orders and forecasts), the bill of materials for each product, and current supply (inventory on hand plus open purchase and work orders). MRP explodes demand through the BOM, nets it against supply level by level, offsets each requirement by its lead time, and produces a time-phased list of planned purchase orders and planned work orders.
That is all MRP does, and it does it well. It does not take the order, invoice the customer, pay the supplier, cost the product or close the month. Those happen somewhere else, and the quality of the plan depends on how current that somewhere else is.
What ERP does
Enterprise resource planning is a single system and database for the transactions that run the business: sales, purchasing, inventory, production, shipping, finance and, increasingly, planning and analytics. In a manufacturing ERP, MRP runs inside the system, reading the same sales orders, inventory and work orders that everyone else uses and writing its planned orders back into the same place.
The phrase MRP II, manufacturing resource planning, sits between the two. It extended MRP to capacity, labor and shop floor control, and ERP grew out of it by adding finance and the rest of the business. Most modern manufacturing ERPs, NetSuite included, cover what MRP II described and more.
The real difference: where the data lives
A standalone MRP tool needs data from the systems that hold orders, inventory and purchasing. Usually that arrives by import, nightly at best, sometimes weekly from a spreadsheet. The plan is therefore always a little out of date, and every planner learns to adjust it by hand: this order already shipped, that receipt came in yesterday, the customer moved their date. Adjustments made outside the system are invisible to everyone else.
With MRP inside the ERP, the plan reads the live sales order book, the inventory that was counted this morning and the purchase order that was expedited an hour ago. Planned orders can be firmed and released as real purchase orders and work orders in the same system, with the same items and vendors, without retyping. Costing, cash planning and customer promise dates all draw on the same numbers. That is the difference that matters day to day.
When standalone MRP is enough
- A small number of products with stable, shallow bills of materials.
- Low order volume, where a weekly plan is fresh enough.
- Accounting that genuinely does not need inventory or production detail beyond month-end totals.
- A planner who has time to reconcile the plan by hand and does it reliably.
Signs you have outgrown it
- Planners ignore the plan. If the MRP output is a starting point that gets rewritten in a spreadsheet every week, it is not the plan.
- Inventory and the books disagree. Month end involves reconciling what the MRP tool, the accounting system and the warehouse each believe is on hand.
- Customers get dates nobody can keep. Sales promises from one system while production plans from another.
- Costs are guesses. Product cost lives in a spreadsheet because no single system sees both what was bought and what was used.
- Growth means more people, not more output. Each new product line adds a planner or an analyst to keep the systems in step.
How MRP works in NetSuite
NetSuite’s material requirements planning runs inside the same account as sales, purchasing, inventory and finance. It reads demand from sales orders and from demand plans, explodes it through bills of materials, nets against on-hand inventory and open supply, applies lead times and planning parameters, and proposes purchase orders, work orders and transfer orders for review. Planners firm and release them as real transactions. Our page on MRP and supply planning in NetSuite covers the setup, and the demand planning guide covers the forecast side that feeds it.
As with any MRP, output quality depends on inputs. The parameters most often wrong in a NetSuite account are supplier lead times (still the original quote, not actual receipt performance), safety stock and reorder points (set once at go-live), and bills of materials that do not include the scrap and components the floor really adds. Fixing those three usually does more for planning than any new feature. See bills of materials in NetSuite for the BOM side.
Capacity is the other half. MRP plans material against infinite capacity; it assumes the plant can build whatever the plan says. NetSuite 2026.2 added rough-cut capacity planning to check a plan against work center capacity before committing to it. For finite, visual scheduling across machines, Consule’s FactorySync schedules NetSuite work orders against real capacity, so the material plan and the production schedule agree.
Choosing
For a manufacturer still running a standalone MRP tool beside an accounting package, the question is less MRP versus ERP and more how much the gap between the two is costing in planner time, excess inventory and missed dates. If those costs are growing, planning belongs inside the ERP. Our guide to choosing a manufacturing ERP covers how to evaluate systems on the processes you actually run.
Consule Solutions implements NetSuite for manufacturers, including planning parameters that the plan can actually be trusted on. If your MRP output gets rewritten every week, talk to us.
Frequently asked questions
What is the difference between MRP and ERP?
MRP, material requirements planning, is a planning method that calculates what materials and production are needed, in what quantity and when. ERP, enterprise resource planning, is a system of record for the whole business: sales, purchasing, inventory, production and finance. A manufacturing ERP includes MRP as one of its functions.
Is MRP part of ERP?
In a manufacturing ERP, yes. MRP runs inside the ERP and reads the same sales orders, inventory and open supply as the rest of the system, then creates planned purchase and work orders in the same place. Standalone MRP tools also exist, which import that data from other systems.
What is MRP II?
MRP II, manufacturing resource planning, extended material requirements planning to include capacity, labor and shop floor control. ERP grew out of MRP II by adding finance and other business functions into the same system.
Does NetSuite have MRP?
Yes. NetSuite includes material requirements planning that reads demand from sales orders and demand plans, explodes it through bills of materials, nets it against inventory and open supply, applies lead times and proposes purchase, work and transfer orders for planners to firm and release.
When should a manufacturer move from standalone MRP to ERP?
When planners routinely rewrite the MRP output, when inventory in the planning tool and the books disagree, when customer promise dates are missed because sales and production use different data, or when growth keeps adding people to keep systems in step.