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Author's profile photo Caetano Almeida

Lot sizing procedure for Make-to-Order

When we are planning a material on an individual stock, such as a sales order stock or a WBS stock, this material is planned on a separate stock segment.

In this case, the existing replenishment elements and the plant stock are not considered by MRP to cover the requirements under this individual stock and new planned orders are created by MRP to cover those requirements.

By default, MRP will consider the standard lot-for-lot logic (similar to lot sizing procedure EX) and it will create replenishment elements to cover exactly the shortage quantity. This standard logic for individual planning was developed, in order to avoid a leftover stock under the individual segment, as it would need an additional goods movement to transfer this leftover from the individual stock to the plant stock.

Considering the example below, where a fixed lot sizing procedure (FX) of 10 was defined for the material. On the Stock/Requirements List (transaction MD04), we can clearly see that MRP created planned orders of 10 EA to cover the Planned Independent Requirements, respecting the lot sizing constraints.

However, for a sales order under the individual sales order stock, a single order planned order of 30 EA was created to cover the sales order requirement, which means that the fixed lot sizing procedure was not considered.


Under specific circumstances, we want to use a different lot sizing procedure under the individual stock, such as a fixed lot sizing procedure or a rounding value for example. In this case, there is a setting on the lot sizing procedure customizing which allows us to choose which logic we want to use under the individual stock segments.

The mentioned customizing can be found in transaction OMI4, as we can see in the image below:

lot sizing.PNG

The options available for this customizing setting allow us to simply consider the rounding or to use the same lot sizing procedure used in the Short-Term Horizon.

lot-size MTO.png

Now, let’s see what happens on the same example if we create a new lot sizing procedure, as a copy of the standard lot sizing procedure FX. Here, we will change the value of the field Lot Size: MtO to 2 – ‘Lot size as in short-term period’ and set this lot sizing procedure for the same material used on the previous example.


Here, we will observe that the same logic used to calculate the quantity of the planned orders created to cover the PIRs was used for the planned orders created under the individual stock. That means, the fixed lot size of 10 was considered under the individual stock.

Besides a sales order individual stock, the same setting is also valid for a project or WBS individual stock.

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      Author's profile photo Saurabh Srivastav
      Saurabh Srivastav

      Hello Caetano Almeida

      I tested this and its working.. Thanks for sharing an eye opener 🙂 ..



      Author's profile photo Former Member
      Former Member

      Hello Caetano,

      Very nice this tip!

      Thanks for sharing.



      Author's profile photo Suresh Mannepalli
      Suresh Mannepalli

      Hi Caetano

      Thanks for sharing your knowledge.

      It is working fine.



      Author's profile photo Former Member
      Former Member

      Hi Caetano,

      Thanks for letting us know.

      Author's profile photo Former Member
      Former Member

      Thanks for sharing this.

      Author's profile photo Bala Subramanian Sankaran
      Bala Subramanian Sankaran

      Hi Caetano,

      Thanks for sharing this useful information.



      Author's profile photo Former Member
      Former Member

      Thank you for sharing the information. regards, Ranga

      Author's profile photo SAGAR SONAWANE

      Wonderfully explained Caetano.. Thanks..

      Author's profile photo Mauro C.
      Mauro C.

      Hi Caetano.

      First of all thank you for sharing.


      I would like to know whether the described behaviour can be set also in case of ATO using production order.


      In our company we would like to generate a production order of 1NR as soon as the sales order is saved. At the moment I can set up everything fine only using MTO, so assembly type = space and auto planning flagged, but the system generates planned order.

      Is it possible? How do I have to set up customizing?


      Thanks for the help.


      Author's profile photo Jeff Lu
      Jeff Lu

      that's a fantastic sharing and documentation!!

      Author's profile photo Akhil Tammiwar
      Akhil Tammiwar

      Hello Caetano Almeida

      Thank you for the information. It is useful. however, when we assign the Production Version to PIR in this case then this setting just does not work. Is there any other setting we need to activate to have this worked with Production Version with PIR?