Routing orders to the right fulfilment centre is a science. Discover how proximity rules, carrier rates, and stock levels interact to minimise shipping costs.
For any merchant operating more than one warehouse or fulfilment location, order routing is one of the most consequential decisions made thousands of times per day — often without any human involvement. Getting it right can cut delivery times by 40% and reduce shipping costs by 25%.
The naive routing approach is geographic proximity: send every order to the nearest warehouse. This works when all warehouses are fully stocked, but breaks down the moment any location runs short on a high-demand SKU. A proximity-first router will send an order to a closer but stockless warehouse, triggering a split shipment or a delay while stock transfers.
Stock-aware routing checks real-time inventory at every eligible location before assigning an order. If Location A is closer but only has 3 units of a 5-unit order, the router should prefer Location B which has adequate stock — even if it's slightly further from the customer.
Carrier rate integration adds another dimension. Different fulfilment locations may have negotiated different rates with the same carrier, or may have access to different carrier networks altogether. A routing engine that considers carrier rates alongside geography and stock can find lower-cost routes that a purely geographic router would miss.
SLA-aware routing ties the decision to delivery promise dates. If a customer selected two-day delivery, the router should only consider warehouses capable of meeting that SLA given current processing queues and carrier transit times — not just the ones that are geographically closest.
Packro's order routing engine evaluates all four factors — geography, real-time stock, carrier rates, and SLA feasibility — simultaneously for every incoming order. Routing decisions are made in milliseconds, and the decision rationale is logged for every order so you can audit and improve your routing rules over time.
The result for operators running multiple locations is typically a 30–40% improvement in average delivery time, a meaningful reduction in split shipments, and lower carrier spend — all without any manual intervention.
Key Takeaways
- Proximity-only routing fails when high-demand SKUs are unevenly distributed across warehouses
- Stock-aware routing checks real-time inventory at every location before assignment
- Carrier rate integration finds lower-cost routes invisible to geographic routers
- SLA-aware routing ensures only feasible locations are considered for a given delivery promise
- Multi-factor routing typically delivers 30–40% delivery time improvement