Planning parameters in Odoo MRP: lead times and ordering rules

An MRP proposal in Odoo is built from parameters the team has already entered; it is not a judgement the system forms on its own. The quality of any purchase request or manufacturing order proposal therefore depends far more on accurate lead times, quantities, routes and bills of materials than on how often the scheduler runs. This article sets out which demand Odoo actually reads, which lead time governs the proposed date, how a reordering rule becomes a supply document, and the practical order in which master data has to be settled before any suggestion deserves trust. Every duration mentioned here is a planning range rather than a commitment. The rule we start from is simple: the system proposes and the planner decides.

What Odoo reads before it proposes anything

Before a single proposal appears, Odoo gathers demand from several independent sources, and it may gather several of them at once for the same product. The main sources are:

• Confirmed sales orders that still have an open delivery, which create demand on the product in a specific warehouse with a specific need date.
• Reordering rules defined on the product for a given warehouse, which turn a falling forecast into a replenishment proposal.
• Dependent demand from a bill of materials: every manufacturing order consumes its components, creating demand for the quantity per unit multiplied by the order quantity, including scrap when scrap is defined on the component.
• Manual stock moves and internal transfer orders created by the team, which are real demand and cannot be ignored.
• The forecasted quantity in the forecast report, which is what the planner reads to see where the quantity is going rather than where it stands now.

All of these sources converge on the forecasted quantity. If old moves were never closed, reservations were never released, or late deliveries were never rescheduled, the system reads demand that does not resemble reality. Clean open movements are a precondition for planning, which is why a review of MRP planning normally starts from the forecast and replenishment reports before any rule is edited.

Lead times: which one governs the proposal

Odoo does not use a single lead time. It selects the relevant one according to the replenishment route that produced the proposal:

• The manufacturing lead time recorded on the product is used when the proposal is a manufacturing order, and the start date is computed backwards from the need date.
• The vendor lead time recorded on the vendor price line for the product is used when the proposal is a purchase request. If it is left empty, the system treats the product as though it were available with unrealistic speed.
• Days to purchase on the vendor record are added to the lead time to represent the time you need to issue and confirm the purchase order before the vendor begins preparing, so they shift the order date rather than the receipt date.
• The security lead time in the inventory settings adds days ahead of planned dates for both sales and purchases. It is a buffer against delay, not a substitute for correct data.

The lead time that governs the proposed date is the one on the route that produced the proposal, not the sum of every lead time on file. The security lead time shifts the whole date, and its effect becomes visible when planned dates are compared with requested dates. When a product is both manufactured and purchased, the route defined on the product decides which lead time applies, and changing the route changes the entire proposal.

Reordering rules: minimum, maximum and multiple quantity

A reordering rule is an agreement between the planner and the system, and its fields have to be read together rather than one by one:

• The minimum quantity is the trigger point: when the forecasted quantity reaches or falls below it, the system starts proposing.
• The maximum quantity is the replenishment ceiling: the system raises the required quantity to that level, so a maximum far above real consumption accumulates stock that nobody asked for.
• The multiple quantity rounds the required quantity up to a defined multiple, which matters when you buy in fixed packs or on fixed pallets.
• The forecasted quantity within the lead time explains why a proposal appears today rather than tomorrow, because the rule looks ahead by the length of the lead time rather than at the current moment.
• The route, location and warehouse on the rule decide where the quantity is replenished from, and a wrong location here produces a proposal in the wrong warehouse without anyone noticing.

Three things generate most of the noise in the replenishment report: a minimum equal to daily consumption, a maximum that doubles the minimum for no clear reason, and two rules on the same product in the same location. Before editing any rule, ask whether the number is derived from actual consumption or inherited from an old spreadsheet. The practical effect of these settings can be followed on the manufacturing in Odoo page.

Bills of materials, routings, work centres and capacity

The bill of materials is what turns a manufacturing order into component demand, and any error in it passes straight into planning. Verify the quantity per unit, the unit of measure of every component, the scrap percentage if you rely on it, and whether each component is purchased or manufactured. A loose bill of materials produces a shortage of one component and a surplus of another at the same time, and that shows up in planning rather than in stock.

The routing carries the sequence of operations and their timing, and work centres carry capacity and duration per operation, which is what makes scheduling feasible or impossible. When capacity is constrained, the conflict appears in planning rather than in stock, and the planner's decision becomes a capacity decision rather than a quantity decision. Ask the manufacturing team to confirm two points before sign-off: that the operations on the routing match what happens on the shop floor, and that each operation's duration sits in its proper field rather than in free text. A duration written into an internal note is never read by the scheduler and never enters a calculation.

Make to stock or make to order, and where the master production schedule fits

In make to stock, the proposal relies on reordering rules and the forecasted quantity, and inventory is the buffer between demand and supply. Make to order links the chain of documents to a specific sales order, so no intermediate stock remains and any component delay becomes a direct delay on the customer order. Mixing the two policies on the same product is one of the most common causes of repeated, contradictory proposals, so settling the policy is a business decision before it is a configuration decision.

The master production schedule in Odoo is a manual planning tool that works in time buckets and is meant for critical products whose decisions cannot be left to the automated scheduler, while running MRP reads actual demand and reordering rules and proposes supply documents. The second is not a replacement for the first, and many teams confuse the two and then expect the master production schedule to do something it does not do.

The order of fixing master data, and the planner's review loop

Do not start planning before master data is stable, and treat the order itself as part of the work:

1. Units of measure and their conversions, because every quantity afterwards is read in those units.
2. Product categories and their settings, because they carry valuation and inventory rules.
3. Products with their route, manufacturing lead time and the fields that drive replenishment.
4. Bills of materials, routings, work centres and the duration of each operation.
5. Vendors with their lead times, purchase prices and payment terms.
6. Reordering rules, and only then a scheduler run on a limited scope.

Once the data is stable, the review loop begins: open the replenishment report, read every proposal together with its reason, reject what does not match real demand, adjust the quantity or the date, and confirm what you accept. Record the reason for each change, because repeated edits to the same rule signal that the rule needs review, not that the planner is wrong. Keep the loop weekly and fixed, and make sure every decision has a name attached to it. When the loop stalls on data rather than configuration, manufacturing and planning services treat it as a data problem before a configuration problem.

What we do not guarantee

• We do not guarantee a commercial result, a profit level or market share; the effect of planning appears in daily decisions, not in an advance promise.
• We do not offer a binding price before a scope analysis, nor a binding duration before a written scope signed by both parties.
• We do not guarantee that every proposal the system produces is correct; a proposal reflects the data entered, and the planner is the one who decides.
• We do not provide a legal or tax opinion, nor a regulatory ruling; those questions remain with the competent authorities.
• We do not provide any professional certificate and we do not claim any official status with software vendors.
• We do not guarantee a search-engine ranking or appearance in any particular results; everything offered here is professional explanation open to review.