Does a WMS replace the ERP?

No. The WMS does not invoice or keep the accounts. What it does is run the warehouse in a level of detail the ERP does not have, and send it back the data once confirmed.

Which one owns the stock, the ERP or the WMS?

The WMS knows the physical stock by location and lot; the ERP knows the book stock. Integration keeps them in line: every receipt, shipment and adjustment in the WMS is passed on to the ERP.

If I change ERP, do I have to change WMS?

Not necessarily. The integration is rebuilt for the new ERP; the warehouse processes stay the same.

Can I use a WMS without an ERP?

The WMS needs something to give it the articles and the orders. Usually that is the ERP, but it can also be an online shop or files from customers, as at many logistics operators.

How much does it cost to add a WMS to the ERP?

It depends on the modules and the integrations. With Caotic it is quoted once the operation is known; according to its product sheet, the investment pays back within a year.

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Comparison guide · WMS and ERP

WMS or ERP: what each one does and when you need both.

Updated on 27 October 2026 · Binari Software Solutions

Short answer

An ERP runs the company: sales orders, purchasing, invoicing and book stock per warehouse. A WMS (warehouse management system; SGA in Spanish) runs what happens inside the warehouse: which slot each pallet is in, with which lot and expiry date, who moves it and in what order orders are picked. They do not compete: the WMS receives orders from the ERP and sends back receipts, shipments and real stock. You need a WMS when the warehouse has enough SKUs, locations, lots or orders for paper and people’s memory to start letting you down.

Comparison

Criterion	ERP	WMS
What it is for	Running the company: sales, purchasing, invoicing, accounting.	Directing and recording the physical work in the warehouse.
How it sees stock	Quantity per article and warehouse (book stock).	Quantity per location, pallet, lot, expiry date and serial number.
Who uses it	Administration, sales, purchasing, management.	Operators, warehouse managers and, at a logistics operator, its customers.
Locations	Usually not, or a simple list.	Every slot coded; the system decides where to put away and where to pick from.
Lots and expiry dates	Records them on documents.	Applies them when reserving: FIFO, FEFO, quality blocks, quarantine.
Operator tasks	Does not direct them: it prints lists.	Gives the next task on the RF terminal or by voice and confirms it with the barcode.
Stock count	Periodic count and adjustment.	Permanent inventory: every movement is recorded on the spot and counting never stops.
Transport	Delivery note and invoice.	Lorry loading, carrier labels, manifests and the control document (DeCA).
How you notice it is missing	Invoices and orders that do not add up.	Picking errors, slots nobody can find, expiry dates that slip through.

What an ERP does

The ERP is the company’s central system. It records what is sold and bought, what is invoiced and what is in each warehouse for accounting purposes. It knows you have 400 boxes of an article, but it usually does not know which slot they are in, which lot each pallet belongs to or which operator has to go and fetch them.

What a WMS does

The WMS runs the inside of the warehouse. It decides where each receipt is put away, generates the replenishment of picking slots, sequences order picking and gives each operator their next task. Every step is confirmed by scanning a barcode, so stock by location is always up to date and every pallet can be traced from receiving to dispatch.

Is the ERP’s warehouse module enough?

For a small warehouse, with few SKUs, no lots or expiry dates and two or three people who know it by heart, often yes. It falls short when you need to direct several operators at once, work with RF terminals or voice, apply FEFO when reserving, use chaotic location storage, give customers access to their stock or prepare the lorry load and the transport paperwork.

How they work together

Normally they coexist. The ERP sends the WMS the articles and the purchase and sales orders; the WMS sends back what has been received, what has gone out and the stock adjustments. Integration is done through EDI (EDIFACT or XML), web services or files, and it is the part of the project most worth designing carefully: it decides which system owns each piece of data.

What suits you

The ERP is enough if…: you have few SKUs and locations, you do not work with lots or expiry dates, picking errors are rare and stock counts add up without stopping the warehouse.
You need a WMS if…: the warehouse depends on someone knowing where everything is, you pick many orders a day, you work with lots, expiry dates or serial numbers, you are a logistics operator with several customers or you are asked for traceability.
You need both, integrated, if…: you already have an ERP that works for the company and the problem is the warehouse. This is the most common case: you do not change the ERP, you add a WMS to it.

Frequently asked questions

Does a WMS replace the ERP?: No. The WMS does not invoice or keep the accounts. What it does is run the warehouse in a level of detail the ERP does not have, and send it back the data once confirmed.
Which one owns the stock, the ERP or the WMS?: The WMS knows the physical stock by location and lot; the ERP knows the book stock. Integration keeps them in line: every receipt, shipment and adjustment in the WMS is passed on to the ERP.
If I change ERP, do I have to change WMS?: Not necessarily. The integration is rebuilt for the new ERP; the warehouse processes stay the same.
Can I use a WMS without an ERP?: The WMS needs something to give it the articles and the orders. Usually that is the ERP, but it can also be an online shop or files from customers, as at many logistics operators.
How much does it cost to add a WMS to the ERP?: It depends on the modules and the integrations. With Caotic it is quoted once the operation is known; according to its product sheet, the investment pays back within a year.