What is Multi-Source Inventory (MSI)?

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Multi-Source Inventory (MSI) is a native Adobe Commerce (Magento) feature that lets a merchant manage stock across multiple physical locations — warehouses, stores, drop-ship suppliers — from within Magento, rather than tracking a single pooled quantity. Each location is a “source,” and MSI tracks stock per source, then decides how available inventory is presented and where orders are fulfilled from.

The problem MSI solves is that most real businesses hold stock in more than one place, but basic inventory tracking assumes one number. Without MSI, a merchant with three warehouses can’t accurately reflect where products actually are, which leads to overselling, wrong availability, and inefficient fulfillment. MSI models the real-world footprint — multiple sources feeding one or more sales channels — inside Magento natively.

Its core concepts are worth knowing:

• Sources — the physical locations where stock is held (warehouses, stores, suppliers)
• Stocks — virtual groupings of sources mapped to sales channels/websites
• Salable quantity — the aggregated available-to-sell figure calculated across sources
• Source selection algorithm — the logic that picks which source(s) fulfill a given order

MSI matters for merchants running multiple warehouses, physical stores, or fulfillment locations, where accurate per-location stock and smart order routing directly affect shipping speed, cost, and oversell prevention. For simpler operations it can also introduce unnecessary complexity — a single-warehouse store doesn’t need it. For larger or omnichannel operations, MSI provides native order-orchestration basics, though very complex fulfillment often still calls for a dedicated OMS. Its accuracy ultimately depends on stock data staying in sync with the systems of record via ERP integration.