SAP MM02 — Change Material
The material master is the single record describing a thing your company buys, makes, stores or sells. Almost every logistics document in SAP points at one: purchase orders, sales orders, production orders, goods movements, invoices.
It is large, so SAP splits it into views. Basic Data holds facts true everywhere. Purchasing holds settings the buyer needs. MRP holds planning settings. Accounting holds the valuation class and standard price. Sales holds the selling settings. You never open the whole material — you pick the views you want to work on.
The second split is by organisational level. Basic Data applies to the whole client. Purchasing and MRP apply to a plant. Storage data applies to a storage location within a plant. Sales data applies to a sales organisation and distribution channel. So the same material can legitimately have a different MRP type in two plants, and that is not a data error.
Those two splits explain nearly every MM02 question. "I cannot see the field" almost always means the view is not selected. "The change did not take effect" almost always means it was made at the wrong organisational level.
When you would actually use MM02
- Changing an MRP type, lot size or reorder point for one plant.
- Updating a material description or material group.
- Correcting a purchasing value key, a base unit of measure entry error, or a gross weight.
- Setting a material status to block a material from purchasing or from sales.
- Extending an existing material to a view or plant it does not yet have.
What the screen looks like
General data
MRP procedure
The fields, in plain English
MARA-MATNRThe material number. It may be assigned by the system or typed in by the user depending on the material type’s number range configuration.
Watch out: Material numbers are often stored with leading zeros on older systems. A number that "does not exist" may just need the zeros, or may need them stripped — the search help settles it.
MARA-MTARTThe classification that decides which views are even possible and how the material is valued. ROH is raw material, HALB semi-finished, FERT finished, HAWA trading goods, DIEN service. It is set at creation and cannot be edited on this screen.
Watch out: Changing material type is a separate, restricted transaction and has accounting consequences. It is not something to do because a view is missing.
MARA-MEINSThe unit everything else is converted to — stock quantities, BOM quantities, order quantities. PC for pieces, KG for kilograms, L for litres.
Watch out: Once stock exists or documents have been posted, SAP will refuse to change this. That is correct behaviour, and it is why getting the base unit right at creation matters more than any other single field.
MARC-DISMMHow this material is planned in this plant. PD is deterministic MRP driven by actual requirements, VB is a manual reorder point, ND means no planning at all.
Watch out: This is plant-specific. Changing it in plant 1000 does nothing in plant 2000, and forgetting that is a common cause of "MRP did not create anything".
MBEW-BKLASThe key that decides which G/L accounts a goods movement for this material posts to. It lives on the Accounting view and it is where materials management meets financial accounting.
Watch out: Changing it once stock exists will normally be blocked, and where it is allowed it moves value between accounts. Treat it as a finance change, not a data tidy-up.
MARC-MMSTAA code that restricts what can be done with the material in one plant — block purchasing, block production, warn on use. The cross-plant equivalent sits on Basic Data and applies everywhere.
Watch out: This is the polite way to retire a material. Deleting a material master with history behind it is not usually possible or wise.
Step by step
- 1Enter the material number and press Enter.
- 2Tick the views you need in the Select View(s) popup.A view shown in a different colour or marked as not maintained does not yet exist for this material.
- 3Fill in the organisational levels popup — plant, storage location, sales area — for the views you chose.
- 4Make the changes on the tabs. Check the organisational unit shown at the top of each tab.
- 5Save with Ctrl+S.
- 6Reopen in MM03 to confirm the change landed where you intended.
Errors you will hit, and what they mean
The material does not exist or is not activated
Why: Wrong number, leading-zero mismatch, or the material exists but not with the views you asked for.
Fix: Use the search help on the material field rather than typing. If the material is found but a view is missing, extend it with MM01 rather than looking for it in MM02.
Base unit of measure cannot be changed
Why: Stock exists, or documents have already been posted against the material in the current unit.
Fix: There is no clean workaround. If the unit is genuinely wrong, the usual answer is a new material number and a plan to move stock and documents across — not a forced change.
Material R-1001 is currently locked by user DMANCUSO
Why: Another user has the material open in change mode.
Fix: Wait for them to finish. Note that the lock is on the material, so it blocks every view, not just the one they are editing.
Field is displayed but cannot be changed
Why: The field selection configuration for the material type, plant or transaction has set that field to display.
Fix: This is intentional configuration, not a fault. Raise it with whoever owns material master governance rather than looking for another transaction that lets you past it.
Common questions
What is the difference between MM01, MM02 and MM03?
MM01 creates a material, and is also what you use to add a view or a plant to a material that already exists. MM02 changes data on views that are already there. MM03 displays without any possibility of changing. Most people need MM03 far more often than they think.
Why can I not see the MRP view for this material?
Either it was never created for that plant, or you did not tick it in the Select View(s) popup. If the view genuinely does not exist, MM01 is what extends it — MM02 can only change what is already there.
How do I change the same field on hundreds of materials?
Not one at a time in MM02. Mass maintenance transactions exist for exactly this, and for very large or structured loads a migration tool is the right answer. Ask before you start clicking — an afternoon of MM02 is usually a ten-minute job in the right transaction.
Transactions that go with MM02
Reading about it only gets you so far
Practise SAP transactions in a safe simulated environment and keep what you learn.
Practise SAP transactions hands-on
Interactive modules, games, and an AI tutor — free to start.
Get started free →