If you're a manufacturer struggling with running out of materials mid-production, over-ordering and tying up cash in excess inventory, or spending hours manually calculating what to buy and when — you need to understand Material Requirements Planning (MRP).
In this complete guide, we'll explain exactly what MRP is, how it works, the key benefits it delivers, and how to implement it in your manufacturing business — even if you have a limited budget.
📖 MRP Definition
Material Requirements Planning (MRP) is a production planning and inventory control system used by manufacturers to calculate exactly what materials are needed, in what quantities, and when they need to be available to meet production schedules.
MRP answers three fundamental questions: What do we need? How much do we need? When do we need it?
How Does MRP Work?
MRP works by taking your production schedule and working backwards to determine what materials must be ordered and when. It combines three key inputs:
Input 1: Master Production Schedule (MPS)
The Master Production Schedule tells your MRP system what products you need to manufacture, in what quantities, and by what dates. For example: "We need to produce 500 units of Product A by March 15."
Input 2: Bill of Materials (BOM)
The Bill of Materials is a complete list of every component, sub-assembly, and raw material needed to produce one unit of your product. For our Product A example, the BOM might include: 2x Component X, 5x Component Y, 1 meter of Material Z.
Input 3: Inventory Records
MRP checks your current inventory to determine what you already have on hand, what's on order from suppliers, and what's already allocated to other production orders.
The MRP Calculation
Net Requirements = Gross Requirements – On-Hand Inventory – Scheduled Receipts
# Example:
Gross Requirements: 500 units of Component X
On-Hand Inventory: 150 units
Scheduled Receipts: 100 units (arriving next week)
────────────────────────────────────
Net Requirements: 500 – 150 – 100 = 250 units to order
A Real-World MRP Example
Let's walk through a practical example. Imagine you run a furniture manufacturer and you need to produce 100 dining chairs by April 1.
| Component | Per Chair (BOM) | Total Needed | In Stock | Order Quantity |
|---|---|---|---|---|
| Chair Legs | 4 | 400 | 120 | 280 |
| Seat Cushions | 1 | 100 | 35 | 65 |
| Back Rails | 2 | 200 | 200 | 0 (enough) |
| Screws (pack) | 1 | 100 | 18 | 82 |
| Wood Stain (L) | 0.5 | 50 | 8 | 42 |
MRP automatically performs this calculation for every component across all your production orders simultaneously — something that would take a human hours to do manually and is prone to costly errors.
Key Benefits of MRP for Manufacturers
MRP vs. MRP II vs. ERP: What's the Difference?
MRP (Material Requirements Planning)
The original system focused purely on material planning — calculating what materials to order and when. Developed in the 1960s, it revolutionized manufacturing.
MRP II (Manufacturing Resource Planning)
An evolution of MRP that expanded to include capacity planning, labour scheduling, and financial planning alongside material planning. Became the standard in the 1980s.
ERP (Enterprise Resource Planning)
Today's ERP systems include MRP and MRP II functionality plus accounting, HR, CRM, and all other business functions in a single integrated platform. ProductionPlannerPro includes full MRP functionality as part of its production planning suite.
How to Implement MRP in Your Manufacturing Business
Step 1: Build Accurate Bills of Materials
Your MRP is only as good as your BOMs. Before implementing any MRP system, audit your Bills of Materials to ensure every component, quantity, and specification is accurate. One wrong BOM quantity will cascade into incorrect purchase orders.
Step 2: Establish Accurate Inventory Records
Conduct a physical inventory count and reconcile with your records. Your starting inventory data must be accurate for MRP calculations to be reliable.
Step 3: Define Lead Times
For each material and supplier, establish accurate lead times (how long from order to delivery). MRP uses lead times to calculate when to place purchase orders to ensure materials arrive exactly when needed.
Step 4: Choose Your MRP Software
For small to mid-size manufacturers, ProductionPlannerPro includes a full MRP module at $30/month — far more affordable than standalone MRP systems or enterprise ERPs that cost $100,000+.
Step 5: Enter Your Production Schedule
Input your production orders and delivery dates. Your MRP system will immediately calculate material requirements, check inventory, and generate purchase order recommendations.
🚀 Try MRP for Free
ProductionPlannerPro includes full MRP functionality — automatic material calculations, purchase order generation, inventory tracking, and supplier management. Try free for 14 days.
Start Free Trial → See MRP Features