LRP vs MRP: Why Your Production Planning Takes Hours Instead of Minutes

Every production planner knows the frustration: you kick off an MRP run at 6 PM, and by the time it finishes hours later, two rush orders have already changed everything. The plan was outdated before it was even printed.

This is not an edge case. It is the daily reality for thousands of Thai factories running traditional MRP. And it raises a question that most ERP vendors prefer to avoid: why does production planning still take so long?

The MRP Problem Nobody Talks About

MRP — Material Requirements Planning — was designed in the 1970s for a world of batch processing and overnight mainframe runs. The core logic is straightforward: take the master production schedule, explode the BOM (Bill of Materials) for every item, check inventory, and calculate what needs to be purchased or produced.

The problem is scale. MRP recalculates everything — every active item, every level of the BOM, every open purchase order, every work order in progress. For a typical Thai factory with thousands of active items and multi-level BOMs, this process takes hours. Some factories report MRP runs of 4 to 8 hours for a single cycle.

During those hours, the shop floor keeps moving. New orders arrive. Customers call asking about delivery dates. Material shipments are delayed. But the planner cannot answer any of these questions until the MRP run completes — and by then, the inputs have already changed.

This is the planning-versus-reality disconnect. The longer the planning cycle, the wider the gap between what the system recommends and what the factory actually needs. Planners compensate by padding safety stock, over-ordering materials, or simply relying on gut feel — none of which is a real solution.

What If You Could Plan Per Order?

LRP — Lot Requirements Planning — flips the approach entirely. Instead of recalculating the entire factory from top to bottom, LRP calculates material requirements for a specific production order.

The logic is targeted: given this one order, what materials are needed? What is already in stock? What is allocated to other orders? What needs to be purchased, and when? LRP answers these questions in under a minute, because it is only looking at one order’s worth of data — not the entire factory.

This changes the nature of production planning from a batch activity to a real-time conversation. The planner is no longer waiting for a nightly run. They are getting actionable answers right now, for the order that matters right now.

How LRP Works in Practice

Picture a typical scenario. It is 10 AM on a Tuesday. A customer calls with a rush order for 500 units of a product that requires 12 different materials and 3 production stages.

No waiting for a full MRP cycle. No opening a spreadsheet to manually check stock levels. No calling the warehouse to ask what is actually on the shelf. The system gives the planner a complete picture for that specific order, immediately.

Why This Matters for Thai Manufacturers

Thai manufacturers often operate in a different rhythm than their Western counterparts. Orders tend to be smaller, more frequent, and more varied. A factory might receive 20 to 30 new orders per day from different customers, each with different product configurations, quantities, and delivery requirements.

In this environment, the question that matters most is deceptively simple: “When your customer calls about delivery, can you answer in 10 seconds?”

With traditional MRP alone, the honest answer is usually no. The planner needs to wait for the next run, or make an educated guess based on experience and a rough check of stock levels. Both options carry risk — promise too early and you miss the date; promise too late and you lose the order to a competitor.

LRP makes the 10-second answer possible. The planner can run a quick requirements check while the customer is still on the phone, and give a confident delivery commitment backed by real data — not guesswork.

For factories that compete on responsiveness — and in Thailand, that is most factories — this is not a nice-to-have feature. It is the difference between winning and losing orders.

The Competitive Reality

Most ERP systems on the market still only offer traditional MRP. The planning cycle is a batch process: collect data, run the engine, distribute the results, repeat tomorrow. If you need faster planning, the typical answer is to bolt on a separate APS (Advanced Planning and Scheduling) system.

The problem with that approach is cost and complexity. A standalone APS system can cost as much as the ERP itself. It requires its own implementation, its own data integration, its own training. You end up maintaining two systems to solve a problem that should have been solved by one.

DigiWin takes a different approach. LRP is built directly into the DigiWin manufacturing ERP, alongside AMRP (Advanced Material Requirements Planning) — a capacity-aware planning engine that considers machine availability, workforce constraints, and production sequencing. No separate purchase. No separate integration. It is part of the standard manufacturing planning toolkit.

The result is a planning environment where nightly MRP handles the big picture, LRP handles the minute-by-minute order questions, and AMRP ensures that plans are feasible given actual capacity — all from a single system, with a single data source, and no reconciliation gaps between tools.

For Thai manufacturers dealing with frequent orders, tight delivery windows, and customers who expect immediate answers, this is not just a technical improvement. It is a competitive advantage that compounds with every order.