How to: Stock adjustments across sales channels and locations

Most product businesses think of an inventory adjustment as a way to add stock. But across the SMBs we work with, nearly half of all stock adjustment entries are reductions. That points to a workflow driven more by correction than addition – what most inventory systems call an inventory adjustment rather than a stock replenishment: reconciling physical counts to system records, writing off damaged stock, or fixing an oversell after a busy sales period.  

This guide covers how location and channel affect the way adjustments work, and how to get them right. 

What are the types of stock adjustments? 

There are two types of stock adjustments: quantity adjustments and cost adjustments.  
Each affects different parts of the inventory record and requires a different kind of fix. Running a cost adjustment when the count is wrong leaves the wrong number of units on record. Running a quantity adjustment when the cost is wrong leaves the wrong inventory value. 

A quantity adjustment changes the unit count at a specific location, up or down. Use it when the physical count doesn’t match the system – a missing unit, a damaged item, an oversell. 

A cost adjustment changes the recorded value per unit without touching the count.  
A common trigger is receiving a shipment at a different cost than the purchase order price – the units are in stock, but the valuation needs correcting separately. 

Knowing which type to use is the first variable. The second is location – and for merchants operating across more than one, it’s where most adjustment errors happen. 

How do stock adjustments work across multiple locations? 

Each location holds an independent inventory record. An adjustment made to one doesn’t carry to another. 

Multi-location operations are increasingly common – 38.9% of Katana customers who make stock adjustments do so across more than one location. For those merchants, the same SKU often needs correcting at each location separately. 

Start by identifying which locations are affected – these can be a warehouse, a secondary storage site, or even an FBA location. For each one, create a separate adjustment entry and select that specific location before entering the SKU and quantity. The adjustment only affects the location selected, so working through them one at a time ensures each record is corrected independently. 

For corrections covering many SKUs across multiple locations, a bulk import is faster and produces a cleaner audit trail than individual entries. Katana supports both, keeping multi-location adjustments manageable without switching between systems or maintaining separate spreadsheets. 

The same location mechanic applies when you add a sales channel. Each channel connects to a specific location, and updates reach the channel only when the adjustment targets the right one. 

How do stock adjustments work across sales channels? 

Each sales channel connects to a specific inventory location. That mapping determines which stock the channel draws from, and it’s what makes location selection critical when making an adjustment – the adjustment needs to land in the location the channel is mapped to. 

Shopify 

Shopify displays whatever stock count it receives, whether that’s a manual update, a spreadsheet, or an automated push from an inventory system. An adjustment that doesn’t flow through to Shopify leaves the storefront showing an incorrect count, with no error to flag it. 

For teams managing inventory manually, any stock adjustment needs a corresponding update in Shopify as a separate step. For businesses using an inventory system with a Shopify integration, the count should update automatically, but only if the adjustment targets the location mapped to that store. Katana makes that mapping explicit, so there’s no ambiguity about which location drives the storefront count. 

Amazon FBA 

FBA sits in Amazon’s fulfilment network as a separate inventory pool, outside your warehouse and outside Shopify’s native visibility. Adding it creates a second inventory location by definition — one that needs its own adjustment workflow, independent from the warehouse. Adjustments to the warehouse don’t affect FBA counts, and adjustments to the FBA location don’t affect warehouse stock. Both require their own reconciliation cycle. 

In practice, this means setting up FBA as a dedicated location in your inventory system, separate from your warehouse, and running adjustments against it independently. When FBA stock needs correcting, the adjustment targets the FBA location. When warehouse stock needs correcting, it targets the warehouse. The two never overlap. 

Both Shopify and FBA adjustment needs increase significantly during high-volume selling periods, and the data on this is worth knowing before planning your operations calendar. 

How to handle stock adjustment peaks 

Stock adjustments follow sales pressure more than the calendar. Across the businesses we work with, adjustment volume runs 2 to 2.5 times higher in November and December than in January – driven by the same forces that make Q4 the busiest selling period: high order volumes, elevated return rates, and FBA reconciliations after peak velocity. Holiday return rates alone run 17% above the annual average (NRF, 2025), with 20 to 25% of holiday purchases returned. Each returned unit re-entering stock is a quantity adjustment. 

This isn’t a pattern that affects every company equally. It’s most pronounced for businesses running high-volume sales events – the correction workload from a Black Friday or Cyber Monday campaign is meaningfully higher than a typical month. 

To stay on top of it: 

Before the peak 

Confirm FBA location counts are current and location mappings are correct across all channels. 

During the peak 

Process returns as they arrive rather than batching them. Each return that re-enters stock needs a quantity adjustment against the right location. 

After the peak 

Run oversell corrections and FBA reconciliations before the next selling period opens. Deferring them to year-end means running the next period on stale counts. 

How to run stock adjustments at scale 

Individual entries work well for isolated corrections, a single SKU at a single location. For stocktake corrections and post-peak reconciliations covering many SKUs across multiple locations, a bulk approach is more practical. 

For teams managing inventory in spreadsheets, this typically means maintaining a master file with location, SKU, quantity, and cost per unit, updating it after each correction, and pushing the changes to each sales channel manually. It works at low volumes, but as the number of locations and channels grows, the risk of version mismatches and missed updates grows with it. 

A dedicated inventory system handles the same corrections through a bulk import, with the audit trail, channel syncs, and location tracking built in. In Katana, every bulk adjustment is timestamped and recorded alongside your orders and stock movements – giving you a single, traceable history of what changed, where, and when. 

One detail worth getting right from the start: location names. Bulk imports reference locations by name. Renaming a location after building templates breaks the mapping, and imports fail without a clear error indicating why. Treat location names as fixed once your workflow is in place. 

Andreia Mendes

Andreia proves that even the most technical topics can (and should) be interesting. At Katana, she works with exclusive data from thousands of product SMBs and turns those insights into practical content for growing brands — covering everything multi-channel merchants need to know about inventory management.