What is MRP?
MRP answers a production question: given what we need to build and what we have on hand, what should we order and make, and when? It works from the bill of materials, current inventory, and demand to generate purchasing and production schedules.
Its scope is planning and materials, not the whole business. MRP will tell you to buy 400 brackets by the twelfth. It will not post the invoice, run payroll, or track the customer relationship.
What is ERP?
ERP is the connected backbone of a business. It brings finance, procurement, inventory, order management, HR, and often manufacturing into a single system with shared data, so a sale, a purchase, and a ledger entry all reference the same records.
Most modern ERP systems include MRP-style planning as one module among many. That is the key point behind the whole comparison: this is usually not two rival products, it is a part and a whole.
MRP vs ERP: a side-by-side
Same question asked five ways. Scroll horizontally on a narrow screen to see both columns.
| Criterion | MRP | ERP |
|---|---|---|
| Scope | Production and materials planning | Whole-business system: finance, purchasing, inventory, HR, manufacturing |
| Core question | What to make and buy, and when | How the entire business's data and processes connect |
| Relationship | Often a module inside ERP | Contains MRP as one part |
| Best fit | Focused planning need | Broad operational consolidation |
| Typical scale | Smaller or single-function | Larger, cross-department |
Signs the gap is planning
- Shortages and expedites surface late, after a job is already on the floor.
- Purchasing works from a spreadsheet rebuilt by hand each week.
- Lead-time promises rest on one person's judgement, not a schedule.
- Finance and HR are basically fine. Materials are the fire.
Signs the gap is breadth
- The same customer or part exists differently in three systems.
- Month-end is a reconciliation exercise between departments.
- Nobody can answer what this job's real margin is without a project.
- Orders get re-keyed between sales, planning, and accounting.
Do manufacturers need MRP, ERP, or both?
It depends on the problem. If the pain is specifically planning, materials, and scheduling, a focused MRP capability may be enough. If disconnected departments and duplicated data are the problem, ERP's breadth is the point.
Many manufacturers already own one or the other and simply need it to work properly with the rest of their tools, rather than a wholesale replacement. Replacing a working system is the most expensive answer to a data-flow question, and it is the one vendors reach for first. A useful build-vs-buy frame is in our off-the-shelf vs custom software guide.
Where does integration fit?
The real-world issue is rarely MRP versus ERP in the abstract. It is that the planning system, the quoting tool, the shop floor, and finance do not talk to each other, so data gets re-keyed and drifts. That is a systems-integration problem: connecting what you already run so information flows once and stays consistent.
- Quote to plan. A won quote becomes a job with its BOM and dates, without anyone retyping it.
- Plan to floor. Schedules and work instructions reach the floor, and actuals come back.
- Floor to finance. Real consumed material and hours land against the job, so margin is measured rather than estimated.
- Costs back to quoting. Current material costs and lead times feed the next quote instead of last quarter's numbers.
AltoLeap builds the custom integrations and operational software that make MRP, ERP, and the rest of your stack work together. See our systems integration work and our custom software for manufacturers guide.
How AltoLeap approaches MRP and ERP questions
We are not an ERP vendor and have no licence to sell you, which means we can be straight about it. Usually the honest answer is that the system you have is adequate at its own job and the cost is in everything around it: the re-keying, the spreadsheet bridges, the numbers that disagree.
So we start from the process, not the platform. Find where data is entered twice, fix that flow, and measure it. If the conclusion genuinely is that you need a different planning system, we will say so. A fixed-scope assessment such as the AI Opportunity Blueprint is the low-risk way to find out before committing to a large project.