Illustrative example with hypothetical quantities: Stock on hand: 80 units, with confirmed sales orders waiting for delivery. The owner or purchasing lead asks: how much do we need to buy now?
Someone who stops at 80 may buy late or buy too much. Purchasing starts with forecasted stock: subtract confirmed deliveries, add incoming supplier receipts, then compare the result with the target level. If 90 units are due out and 30 are due in, the forecast is 20. With a target of 100, the initial need is 80 units before supplier-pack rounding, when forecast stock is below the agreed minimum.
At ToDoOps, we connect that decision to forecasted stock in Odoo, supplier lead times and a named reviewer. Purchasing can explain why an order is needed, and the owner can see what remains after deliveries without collecting separate spreadsheets. Reordering rules define a minimum and a replenishment target, then suggest needs according to the configured route and trigger 1.
Why does the rule suggest buying when stock looks fine?
A purchasing officer opens the morning report and sees an item with 80 units on hand. The rule still proposes a purchase. On-hand stock is part of the calculation, but the comparison uses the forecast within a defined window and lead time: on-hand quantity, plus incoming receipts tied to a date inside the window, minus outgoing demand 1.
The rule applies to a tracked product at a location, and its route is either Buy from a vendor or Manufacture with a bill of materials (BoM). When the numbers look strange, check the forecast window and the movements included in it first.
Manual or Auto: who decides, and when?
- Manual: needs appear on the report and require a person’s review before action.
- Auto: action happens when the scheduler runs, or when a sales order reduces the forecast, as the documentation describes 1.
Manual review can be a useful starting point for expensive or single-source items when your team needs to check quantities before ordering. Auto suits items whose demand and lead time are well understood and have behaved properly in testing. In both modes the purchase output is an RFQ the buyer reviews, and approval and payment remain outside the rule.
Min, Max, and multiples: a hypothetical example
These numbers are illustrative, not client data:
On mobile, swipe the table horizontally if any columns are out of view.
| Item | Value |
|---|---|
| On hand | 80 |
| Incoming, tied to a date inside the window | +30 |
| Outgoing in the window | −90 |
| Forecast | 20 |
| Min / Max | 25 / 100 |
| Quantity before rounding | 100 − 20 = 80 |
| Multiple of 12 (rounded up) | 84 |
| Forecast after the order arrives | 104 (4 above Max) |
A forecast of 20 is below the Min of 25, so the rule fires. Reaching Max needs 80 units, but the vendor sells in packs of 12, so the quantity rounds up to 84. The result lands four units above Max, which is expected behavior with a multiple 1. If that overshoot is a problem because space is tight or the item perishes, revisit Max or the multiple now rather than discovering it later.
To estimate implementation cost, time, and savings on a hypothetical basis only, you can use our calculators. Use them to plan the system implementation budget; order quantities come from product and supplier data.
A small planning sheet before you set Min
A simple planning sheet can estimate need during lead time. Say average demand is 8 units a day, lead time is 5 days, and the safety margin is 10 units:
8 × 5 + 10 = 50
The logic follows a general inventory principle: safety stock covers variability in demand and lead time, and a reorder point is not just a buffer. It is expected demand during lead time plus a margin 2. That source is not a study of ERP improvements, and it does not offer one formula that fits every situation.
Three points matter here:
- The inputs (daily demand, lead time, margin) come from your company’s own data, not from an example in an article.
- The figure of 50 is not an Odoo algorithm, and it is not a value to type straight into Min.
- The rule already accounts for expected outgoing demand inside the window. If you enter 50 as Min without reviewing the window and the lead time, you may count demand during lead time twice.
Lead times: approval is not supply
In the Odoo 19 reference, vendor lead time runs from purchase order confirmation to receipt, while Days to Purchase reflects the time spent reviewing the RFQ 1. Keep them separate. If internal approval takes two days and the vendor needs five, blending the numbers gives you a lead time that describes neither reality.
Choosing items and implementing
- Pick a small set of items that surprise you repeatedly.
- For each, define the location, the vendor or BoM, both lead times, and the multiple.
- Enter the values in a test copy and review what the rule generates with the buyer.
- Run Manual first, then move proven items to Auto.
- Write one line explaining each number so you know when to change it.
We do not repeat cycle counting or batch tracking here; those are separate topics.
Review indicators
- How many RFQs the buyer edited by hand.
- Items whose rounding regularly exceeds Max.
- The gap between actual receipt dates and the recorded vendor lead time.
- Actual stockouts logged by the warehouse, without an invented target figure.
A pattern in any of these is a prompt to review the setup, not a verdict on the rule.
Frequently asked questions
Does the rule buy and pay automatically? No. On the Buy route it creates an RFQ. Approval and payment are separate steps 1.
Why did a need appear when stock is above Min? Because the comparison is against the forecast, and upcoming outgoing demand inside the window may be large.
Does the rule guarantee no stockouts? No. It does not forecast demand. It relies on the numbers you set and the receipt dates recorded.
Next step
Take five items from your own data and write down, for each, the usual demand, the lead time, the approval time, and the vendor’s multiple. Then test the result with your purchasing lead. You can walk through a sales and inventory flow with fictional data in the guided demo. It shows how the sales order connects with stock movements. Browse Odoo apps and industries to see what fits your operation, and try the calculators for a hypothetical estimate of cost and time. If you would like our team to get in touch, request it through the contact page. For an overview of the service, return to ToDoOps.
References
[1] Odoo — official19.0 documentation. Reordering rules and Lead times, reviewed3November2026: forecasted stock, min/max thresholds, pack multiples, buying and manufacturing routes, manual/automatic triggers and replenishment lead times.
[2] Amazon Business — Safety stock: How to calculate it. Rah Chalfant,8September2026. Explains the buffer for demand and lead-time variation and its place within a reorder-point decision.