ERPNext v16 · manufacturing planning
ERPNext v16 brings demand sources, a Master Production Schedule, material requirements and item lead times into a more connected planning flow. This guide explains what each step means for planners, buyers, production teams and management.
What is Material Requirements Planning?
Material Requirements Planning asks three practical questions:
- What finished products, sub-assemblies, components and raw materials are required?
- How much is required after considering demand and available supply?
- When should purchasing or production begin so materials are ready on time?
The value is not simply a longer purchase list. A time-phased plan helps purchasing avoid ordering everything too early, helps production see dependencies and helps sales receive more realistic delivery information.
How ERPNext v16 connects demand to action
1. Demand sources
Official ERPNext documentation describes the Master Production Schedule as collecting demand from sales orders, material requests, sales forecasts and delivery schedules. Each source answers a different planning need.
| Demand source | What it represents | Planning caution |
|---|---|---|
| Sales Order | Confirmed customer demand. | Review cancellations, amendments, delivered quantities and promised dates. |
| Material Request | An approved internal need to purchase, manufacture, transfer or issue material. | Avoid duplicate demand when the same need is already represented elsewhere. |
| Sales Forecast | Expected future demand entered for planning. | Forecasts require ownership, horizon, review frequency and accuracy measurement. |
| Delivery Schedule | Demand distributed across multiple required delivery dates. | Dates need to reflect the customer commitment, not an arbitrary split. |
2. Master Production Schedule
The MPS gives planners one place to consolidate and review demand for finished items before exploding it into component requirements. This is where duplicates, unrealistic dates or sudden peaks should be challenged—not after purchase orders have been raised.
3. Material Requirements Planning report
The MRP report calculates required quantities and dates for materials and components based on finished-goods demand. ERPNext documentation also describes a bucket view, helping users read needs across time periods rather than as one undifferentiated total.
4. Item lead time
ERPNext uses item lead-time information to support the dates on which purchasing raw materials or producing components should begin. If the lead time is missing or optimistic, the calculation may be mathematically neat and operationally late.
MRP quality is limited by the quality of its inputs
Item masters
Correct make-or-buy decisions, UOMs, variants, stock settings and procurement details.
BOMs
Approved component quantities, scrap or process assumptions, alternatives and effective revisions.
Inventory
Accurate warehouse balances, reservations, batches and stock that is genuinely available to the plan.
Open supply
Purchase and production orders with dependable outstanding quantities and expected dates.
Lead times
Realistic procurement and manufacturing time, reviewed when supplier or plant performance changes.
Demand
Confirmed orders and governed forecasts without duplication or expired requirements.
Pre-MRP control checklist
- Reconcile physical and system stock for the items that materially affect the plan.
- Approve current BOM versions and close draft, duplicate or obsolete structures.
- Confirm item UOMs and conversion factors across buying, stocking and manufacturing.
- Review open purchase orders, work orders and material requests for realistic dates and quantities.
- Separate usable stock from rejected, expired, quarantined or customer-owned material.
- Update lead times using observed supplier and production performance, not memory.
- Agree the planning horizon, time buckets, review frequency and decision owner.
- Document how forecasts interact with confirmed demand to prevent double counting.
A practical way to operate ERPNext MRP
Define the planning policy
Agree which products and plants are included, how far ahead to plan, which demand sources to use, when forecasts are consumed and who may approve the result.
Prepare and review demand
Bring relevant sales orders, requests, forecasts and delivery schedules into view. Resolve duplicates, past-due dates and unrealistic peaks with sales and operations.
Create and validate the MPS
Confirm finished-goods quantities and dates. Review capacity and commercial priority before detailed material recommendations are treated as commitments.
Run the MRP report
Review required items, dates and quantities in the appropriate buckets. Investigate unexpected shortages or surpluses by tracing demand, BOM, stock, supply and lead-time inputs.
Convert approved recommendations
Create or plan the relevant purchase and work-order actions only after buyers and production planners review constraints, lot sizes, suppliers and capacity.
Monitor execution and replan
Track delayed supply, changed demand, rejected material and production variance. Update the source data and replan through a controlled rhythm rather than creating parallel spreadsheets.
A simplified MRP example
Assume a manufacturer plans to deliver 500 units of Product A next month. Product A needs two units of Component B and one unit of Component C. The following illustration shows the planning logic at a high level.
| Item | Gross requirement | Usable supply considered | Illustrative net need | Planner action |
|---|---|---|---|---|
| Product A | 500 finished units | 50 finished units available | 450 units to produce | Review the finished-goods plan and capacity. |
| Component B | 900 units for 450 Product A | 300 usable units plus 200 due on time | 400 additional units | Plan purchase or sub-assembly action using lead time. |
| Component C | 450 units for 450 Product A | 500 usable units | No additional quantity in this simplified view | Protect or reserve stock and monitor competing demand. |
This is deliberately simplified. Actual ERPNext results depend on configured demand, BOM structure, warehouses, projected availability, open supply, dates, lead times and other system settings. Use a controlled test case with known expected results before relying on MRP for production decisions.
What should happen after the MRP run?
MRP should create a focused planning conversation, not an automatic flood of orders. Assign clear responsibilities for the review.
| Role | Review responsibility | Decision |
|---|---|---|
| Demand planner / sales operations | Order priority, forecasts, delivery dates and unusual demand. | Confirm, defer or revise demand. |
| Material planner | Shortages, dates, duplicate signals, substitutes and planning parameters. | Recommend purchase, production, transfer or reschedule. |
| Buyer | Supplier lead time, MOQ, price, availability and commercial terms. | Select supplier and purchasing action. |
| Production planner | Capacity, routing, WIP, maintenance, changeovers and labor constraints. | Schedule work and resolve production conflicts. |
| Finance | Cash requirement, inventory exposure and cost effect. | Confirm budget or escalate working-capital risk. |
| Master-data owner | Unexpected results caused by item, BOM, UOM or lead-time quality. | Correct governed data and document the change. |
MRP measures worth reviewing every month
Plan stability
How often do near-term quantities and dates change after approval?
Forecast accuracy
How close was forecast demand to the demand that actually materialized?
Supplier reliability
How often does supply arrive in full and on the date used by planning?
Shortage incidents
Which jobs were delayed by missing material, and which input was wrong?
Excess inventory
Which planned materials remained unused or became slow-moving?
Schedule adherence
How reliably did production complete against the approved schedule?
The purpose of these measures is not to blame the planner. It is to improve the assumptions the next MRP run will use.
Common MRP mistakes—and what they are telling you
| Symptom | Likely issue | Response |
|---|---|---|
| MRP recommends too much material | Duplicate demand, missing supply, wrong BOM quantity or unavailable stock counted incorrectly. | Trace the requirement to its source before reducing it manually. |
| Purchase suggestions arrive too late | Lead time is missing, optimistic or not aligned with the required date. | Update planning lead time from actual performance. |
| Planners still export everything to Excel | They do not trust inputs, exceptions are hard to interpret or responsibilities are unclear. | Fix data and review governance before adding another report. |
| Frequent emergency purchases continue | Forecast horizon, supplier reliability, stock accuracy or replanning frequency is weak. | Measure the cause of each expedite and correct the dominant input. |
| Production has material but cannot start | Capacity, tooling, quality, routing or prerequisite sub-assembly was not considered operationally. | Connect MRP review with capacity and shop-floor planning. |
| Excess inventory grows | Forecast bias, large order quantities, slow schedule response or obsolete demand. | Review policy and ownership, not only reorder settings. |
How we would introduce MRP without overwhelming the team
Choose a representative pilot
Start with one product family that has meaningful demand and BOM complexity but an engaged planning team.
Prove the inputs
Reconcile items, BOMs, stock, open supply and lead times. Use a small expected-result case before moving to broad volume.
Agree the weekly planning rhythm
Define when demand freezes, who reviews MPS, who approves actions and how exceptions are escalated.
Measure the decisions
Track shortages, expedites, excess inventory and schedule changes. Improve data and policy before expanding the scope.
Scale with governance
Add products, plants or planners only after master-data ownership and support responsibilities are working.
Turn MRP into a planning habit your team can trust
We can help you assess manufacturing data, configure ERPNext v16 planning, validate expected results and connect MRP with purchasing, production, inventory, quality and finance across your operation.
Frequently asked questions
What is MRP in ERPNext v16?
Material Requirements Planning in ERPNext v16 calculates the quantities and dates of raw materials and components needed to meet finished-goods demand. It works with demand planning, the Master Production Schedule and item lead-time information.
Which demand sources can feed the ERPNext Master Production Schedule?
Official ERPNext documentation lists sales orders, material requests, sales forecasts and delivery schedules as demand sources used by the Master Production Schedule.
What is the difference between MPS and MRP?
The Master Production Schedule expresses when and how much finished product is planned. MRP uses that demand and product structures to calculate the materials and components required to support it.
Does ERPNext MRP automatically create purchase and work orders?
ERPNext can support actions from planning results, but organizations should define approval and review rules. Buyers and production planners should evaluate supplier, capacity, cash, quality and operational constraints before recommendations become commitments.
Why are our ERPNext MRP results inaccurate?
Common causes include incorrect stock, obsolete BOMs, inconsistent UOMs, duplicate demand, unrealistic lead times, outdated open orders and ungoverned forecasts. Trace an unexpected result through each input before overriding it.
Can ERPNext MRP prevent stockouts?
MRP can make future shortages visible and support earlier action, but it depends on accurate data, supplier and production execution, regular replanning and accountable decisions. It cannot compensate for consistently incorrect inputs.
Who should own MRP in ERPNext?
A material or production planning owner should operate the process, with clear contributions from sales, purchasing, production, warehouse, finance and master-data owners.
Primary references
- ERPNext documentation: Material Requirements Planning
- ERPNext documentation: Stock Reservation for Production Plan
- Official ERPNext release notes
Feature behavior and fields can change by release and configuration. Validate the exact ERPNext version in a test environment and reconcile results using your own production data and approved planning rules.