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We know unit of measure is a vital thing which is used in material master, purchasing document and inventory management etc.  I hope I do not need to elucidate about what a unit of measure is and where it is used. There are lots of SAP help document where you will find all type of details for unit of measure. As we know, there are certain type of unit of measure is used in material master, purchasing document and inventory management like as Base unit of measure, Order unit, Order price unit, stock keeping unit, even you can find more in this SAP help document Units of Measure – Material Master (LO-MD-MM) – SAP Library

Here, I’ll explain how it is used in a purchasing document, from where it can be defaulted, what the priority is for fetching this unit of measure and how the calculation of conversion will be calculated during a creation of purchasing document and goods movement.

As we know, in purchase requisition, we can only have the base unit of measure as unit of measure (EBAN-MEINS). We can’t use any kind of alternate unit of measure (MARM-MEINH) or order unit (MARA- BSTME) in purchase requisition. It is SAP standard design and we can’t change it.

There is another unit of measure field in purchase requisition that is called PO unit (EBAN-BMEIN), this field is used to default the order unit during creation of purchasing document (e.g. Contract, RFQ, Purchase order or Schedule agreement). This field value if coming from source list maintained for the material in ME01 (EORD- MEINS). If there are no source list, then system will pick the unit from source of supply (can be an agreement or a purchase info record).

In this source of supply tab in purchase requisition, you can see multiple order units with regards to same info record. It is depend upon your selection of the tick option “Source determination” (MEREQ_TOPLINE- KZZUO), if you tick this option, then you can’t see multiple order units in this tab, system will fetch only the order unit which is maintained in info record (EINA-MEINS). But if you do not tick this option, then you can able to see all unit of measures which are maintained in your info record condition tab (in case of Variable Purchase Order Unit in active (as 2 – Active with own price) and condition is maintained as per this document Create Info Record for different Order Unit)

In a purchasing document, we can use an alternative unit of measure which is defined in material master (if you are using material master in your purchasing document). If you are not using any material master (for account assigned purchasing document), you need to enter the order unit manually for purchase order line item.

There are some priorities for the order unit (EKPO-MEINS) from where system will fetch the unit of measure. Let’s explain how system reads the unit of measure and how the conversion is calculated during purchasing document creation.

There are 3 ways from where system can fetch the order unit for a purchasing document:

  1. Reference document
  2. Purchase info record
  3. Material master

First priority will be always reference document. If you are creating a purchase order with regards to a contract, then system will always copy order unit (from EKPO-MEINS) and order price unit (from EKPO-BPRME) and all conversion factors from contract and you can’t able to change this order unit. In that case, system will make the order unit as grey mode, but still you can change the order price unit. System will ignore all other reference (like purchase info record or material master).

If you are using a purchase requisition as reference, then order unit will be copied from PO unit (EBAN-BMEIN, which is exists in source of supply tab), here system will allow you to change the order unit. If this field (EBAN-BMEIN) is blank, then system will fetch the order unit from purchase info record.


Second priority will be purchase info record. If you are not using any reference purchasing document, then system will always copy order unit (from EINA-MEINS) and order price unit (from EINE-BPRME) and all conversion factors from purchase info record. In that case, system will allow changing both order unit and ordering price unit.

==>Note: You can always change the order unit in info record (EINA-MEINS) as per your requirement, but system will not update any old purchasing document which was already created by using this info record. It will effect only for new purchasing document.


Third priority will be material master record. If you are not using any reference document or any purchase info record, then system will fetch the order unit and conversion factor (from MARM table) from material master (in that case, order price unit will be same as order unit). First, system will search for the order unit maintained in material master (MARA- BSTME), if there is no order unit, and then system will pick the base unit of measure from material master (MARA- MEINS) as order unit in purchase order line item.

==>Note: If you are using Variable Purchase Order Unit as active (1 or 2), then system will propose base unit of measure as order unit in purchasing document, if there is no order unit maintained in material master. If you active Variable Purchase Order Unit, then system will allow you to change order unit as per your requirement, you just need to maintain the conversion factor in material master. Remember, if you change the order unit manually, then system will not change order price unit automatically, system keeps the existing order price unit, you need to change it manually also.


For the conversion factor, system will always fetch the conversion factor accordingly with regards to the reference document (if any). In case of batch specific conversion, system will ignore all other conversions. The prerequisite is your order unit has to be matched with batch unit.

At the time of creating a service purchase requisition or purchasing document (by using item category D), system will use a default unit of measure (T165-PER_MEINS) which is defined in ML91 and you can’t change it further. For a service requisition or purchasing document, system will always consider the unit of measure which is entered in service tab (ESLL- MEINS) for further process. By the way, changing the order unit (EKPO-MEINS) is controlled by field selection of item category D (field selection PT9F).

==>Note: As of release 606, system will change automatically the purchase order line item’s order unit (EKPO-MEINS) by service tab’s order unit (ESLL-MEINS).


In case of creating an intra-company stock transport order (by using item category U and document type UB), system will not consider the order unit. System will fetch the value from unit of issue (MARC- AUSME). Cause of this behavior, plant to plant transfer is not correspond to purchasing, it quite comes under transfer posting; hence system will not pick the order unit which is maintained in material master. If there is no value defined in this field (unit of issue), then system will fetch the base unit of measure as order unit in stock transport order. In case of using Variable Purchase Order Unit (1 or 2), system will consider Unit of issue as order unit, but then it is possible to change it as per requirement. For inter company stock transport order (using document type NB), system will consider order unit as per normal purchase order.

==>Note: This field (unit of issue) value can be stored in material master (MARC-AUSME) different with regards to plant and also by using unit of issue in material master (MARC- AUSME), system will also consider this unit of measure as ‘Component unit of measure’ in CS01 (STPO-MEINS).


Remember, system will never change any conversion factor or order unit in purchasing document automatically. If there are any changes in material master or info record after a purchasing document created, then you have to create a new purchasing document to bring this new effect. If you carry out any further process (e.g. goods receipt) for any existing document, then system will carry the old order unit or conversion factor for further process.


During goods receipt with regards to a purchase order or schedule agreement, system will always propose you order unit as ‘Unit of Entry’, but you can always change this unit as per your requirement. You just need to be sure that conversion factor of this new unit is maintained in material master; system will pick this conversion from material master. In the same way, during transfer posting, system will allow you to enter different unit of measure in the field ‘Unit of Entry’, system will take the conversion factor from material master. If you will not enter any unit of entry during transfer posting, then system will pick the base unit of measure as unit of entry. For valuation during goods receipt, system will always use the order price unit for GR/IR clearing account’s value and base unit of measure will be considered for stock account line item posting. During physical inventory document, you have the option to enter Unit of entry in MI04 (during count) and MI10 (Create List of Differences w/o Doc.) manually. System will always propose the base unit of measure in this field (Unit of entry (physical inventory)) (ISEG-ERFME), But you can change it from default to any other as per your requirement. You just need to be sure that the conversion factor is maintained in material master. System will take the conversion from material master (MARM table). Once you will enter a different unit of entry in this field, system will calculate the quantity for Base Unit of Measure (ISEG-MEINS) automatically as per maintained conversion in material master.

==>Note: Even though you are using any different unit as ‘Unit of Entry’ during a goods receipt or transfer posting or physical inventory process, system will always update stock as per stock keeping unit (which is base unit of measure). System will update all unit of measures in MSEG table (ERFME = Unit of Entry, MEINS = Stock keeping unit, BSTME = Purchase order’s order unit). Conversion factor will be used as ERFME to MEINS will be picked from material master (MARM table); BSTME to MEINS will be picked from purchasing document (EKPO table). In MB52, you can only see the unit for stock as per base unit of measure, but in MMBE, you can see the stock with different alternative unit of measure by selecting the unit in the field ‘Display Unit of Measure’. In that case, system will calculate the conversion from material master. If you are changing the alternative unit of measure frequently (after done some posting), then you may can see wrong data by using this option, as because system will always take the current conversion from material master.


During sales order creation, system will propose the Sales unit (MVKE-VRKME) from material master for sales order line item (VBAP- VRKME), if the field Sales unit (MVKE-VRKME) is blank in material master, then system will pick the base unit of measure as sales unit. Here, system will allow you to change the unit of measure for sales order item (VBAP- VRKME); you just need to be sure that conversion factor is maintained in material master. You can maintain a different conversion factor for this sales order line item. Once you will change the Sales unit, then you need to change the Condition unit in the document manually. System will not change the Condition unit in the document automatically.

==>Note: In material master, you can use different sales unit as per combination of Sales Organization and Distribution Channel. You may be able to restrict changes for this field via screen variant.


Here is some reference documents for more details about unit of measure.

SAP help documents:
Units of Measure in Purchase Orders – Purchasing (MM-PUR) – SAP Library

Units of Measure in Inventory Management – Inventory Management and Physical Inventory (MM-IM) – SAP Library


Reference OSS notes (KBA and Recommendation note):

187511 – Redesign quantity conversion

1836255 – Units of Measure used in the Valuation of WRX and BSX

77525 – Quantity unit conversion in inventory management

1772735 – Stock Report with Alternative Unit of Measure

1981710 – Wrong unit of measure in RFQ (reference for quotation )

1795967 – If the requisition is generated via MRP the Order unit is not copied from the source list

445239 – ME56/ME57-Source Overview displays numerous OUn

2027096 – Service Purchase Requisition UOM is defaulted and can not be changed at item level.

138767 – Changing the base unit of measure

1597737 – Purchasing Order unit is not defaulted into UB Document type

1994263 – Change of order unit does not update condition unit in Info record

2100007 – Fields about PO Conversion of Order Unit to Base Unit can not be set as editable

1980679 – Why the field ‘Unit of Issue’ of the supplying plant is taken in STO?

SAP OSS notes for program correction regarding unit of measure:

1304204 – Purchase requisition services, no ISO unit of measure

885453 – ME21N: Message 06 480 for PReq without material number

1662759 – Order Unit not derived while creating Outline Agreement

872955 – ME5xN: F4 help for units of measurement in item overview

1115005 – ME51N: Check against the unit UoM of the source of supply

1128924 – Quantity conversion doesn’t happen from PR->PO

1714849 – MIRO: Qty conversion in base unit of measure (ACCTIT-MENGE)

1607326 – ME11: Order Unit not taken from material master

1719704 – ME12: Wrong conversion factor after order unit change

1068670 – Units of measure using BAPI_SAG_CREATE/BAPI_CONTRACT_CREATE

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