Short answer
A warehouse management system (WMS) tracks which bin every item sits in, where incoming goods should go and which bin to pick from first. ERP knows how many you have and what they are worth. You need a WMS with many SKUs, several warehouses or zones, lot or expiry control, or hundreds of picks a day.
Key points
- ERP answers how many and how much; a WMS answers where, and which bin to pick next.
- FIFO and FEFO only work when the system knows which lot sits in which bin.
- Try the storage locations in your current ERP's inventory module before buying a separate WMS.
- Warehouse rollouts usually fail on starting data that does not match the shelves, not on the software.
What is a warehouse management system (WMS)?
A WMS tracks stock by its physical location, such as zone A, shelf 3, bin 12. Every time goods arrive, move or leave, staff scan the item barcode and the bin barcode, so the system knows where things are, not just how many there are.
A good WMS tells staff where to put stock away and which bin to pick from, instead of relying on memory.
- ReceiveCheck incoming goods against the purchase order
- Put awayThe system names the bin; staff scan it to confirm
- PickPick each order from the bins the system assigns
- Pack and shipPack to the order and dispatch
- Cycle countCount in rounds and compare with the system
What is the difference between ERP and WMS?
ERP answers how many and how much. A WMS answers where, and what to do next. They work together: the WMS posts receipts and issues back to ERP, which does the accounting.
| ERP or accounting inventory | WMS | |
|---|---|---|
| Answers | Quantity, value, cost of sales | Location, where to store, where to pick |
| Tracks by | Warehouse or branch | Bin, lot and expiry date |
| Main users | Accounting, purchasing, sales | Warehouse staff and supervisors |
| Hardware | Office computers | Phones or barcode scanners on the floor |
| Success means | Correct financial statements | Right item, fast picks, counts that match |
Signs you need a warehouse system
If several of these apply, the problem is not the count in the system but that nobody knows where things physically are.
- The system says it is in stock but nobody can find it
- Wrong models, colours or sizes are picked and come back as returns
- Every annual stock count disagrees with the system
- Older lots or near-expiry goods should go first, but do not
- You run several warehouses or zones and transfer stock between them often
- New staff take a long time to learn where things are kept
What is the difference between FIFO and FEFO?
FIFO (first in, first out) ships the oldest stock first and suits general goods. FEFO (first expired, first out) ships whatever expires first, for food, medicine, cosmetics and anything with a shelf life.
Both only work if the system knows which lot sits in which bin. When it only knows the total, staff pick from the nearest bin.
System knows totals only
- Knows how many, not which lot is where
- Staff pick from the nearest bin
- Old or near-expiry stock sits at the back
System knows lots by bin
- Points staff to the lot that must leave first
- FIFO or FEFO happens on every pick
- Nobody has to remember which lot is where
What are the options for a warehouse system?
You do not have to start with a full WMS. Many ERPs have an inventory module with storage locations, such as Odoo Inventory. If you already run that ERP, switch those locations on first.
If your warehouse has its own steps, such as receiving from a production line, cutting lots by recipe or connecting to a transport system, a purpose-built warehouse system linked to your existing ERP usually fits better.
- Switch on storage locations in your current ERP's inventory module
- Subscribe to an off-the-shelf WMS and connect it to your ERP or accounting software
- Build a warehouse system for your workflow, with phone barcode scanning, posting totals to ERP
How to roll out a warehouse system without stalling
Get the starting data to match the shelves first. Warehouse systems break most often at go-live, and the cause is rarely the software. The order that works:
- Bin codesCode every bin and label it with a barcode
- Product codesClean duplicates so each product has one code
- Opening countCount zone by zone and record it as the opening balance
- One zone firstStart in one zone until scanning every move is habit
- Cycle countsReplace the annual count with weekly counts of one section at a time
Before investing in a warehouse system
- Is the problem wrong counts, or not finding items?
- Does every bin have a location code?
- Does each product have exactly one code?
- Do you need lot or expiry control?
- Does your current ERP already support storage locations?
- How will warehouse movements post back to accounting?
Frequently asked questions
Do I need both ERP and a WMS?
Not always. A business with one warehouse and a modest product range is often fine with ERP inventory and barcodes. A separate WMS pays off with large or multi-zone warehouses, high daily pick volumes, or lot and expiry control. If you run both, the WMS must post receipts and issues back to ERP automatically.
Is there a free warehouse management system?
Yes. There are free stock programs and open-source ERPs with an inventory module, such as Odoo Community. But the real cost of a warehouse system is usually coding the bins, labelling them with barcodes, counting the opening stock and training staff, not the software licence.
Can I run a warehouse on Excel?
Early on, yes, while the product range is small and one person edits the file. Once several people receive and pick at the same time, the spreadsheet drifts away from the shelves, because nothing records the movement at the moment and place the goods actually move.
Can Odoo work as a warehouse management system?
To a point. Odoo's Inventory module supports storage locations inside a warehouse, so if you already run Odoo, switch that on before buying a separate WMS. If your warehouse has specialised steps, such as receiving from a production line or connecting to a carrier, a purpose-built system linked to Odoo usually fits better.