Warehouse slotting for ecommerce: cut walking without creating new bottlenecks

Good warehouse slotting puts frequently picked products in locations that are easy to reach, easy to replenish and suitable for the product. Start with how often a SKU appears in the picking workload. Then account for its size, handling requirements and the products usually ordered with it.

The aim is to reduce the work needed to ship an accurate order. A shorter walk helps, but a crowded aisle or constantly empty pick bin can consume the time you saved.

You can test a better layout in one small zone before moving the whole warehouse.

Rank products by picking work, not sales revenue

A high-priced item sold twice a week may generate more revenue than an inexpensive accessory picked 150 times a day. The accessory usually deserves more attention in a slotting review.

Export four to eight representative weeks of order lines as a starting point. Separate unusually large promotions so they don't silently dictate the everyday layout. Shopify's order export documentation identifies the order ID, line-item SKU and line-item quantity fields. Additional items can occupy separate rows, so a row count isn't an order count.

Create one row per SKU with these fields:

Use warehouse management system task data when available. In batch picking, one visit may supply several orders. Counting every order line as a separate physical trip would overstate the opportunity.

Also flag stockout periods. A SKU that couldn't be purchased for half the month may look slow simply because it was unavailable.

Give each SKU a suitable home

A useful “golden zone” is the area where repeated picks require little bending, reaching or unnecessary travel. Its height and depth depend on the person, product and equipment.

The Canadian Centre for Occupational Health and Safety recommends placing heavy and frequently used materials around waist height, while considering the people who use the storage area. Its storage layout guidance also addresses aisle space and avoiding awkward access.

Apply those principles within the location's load rating and the site's handling procedures. A popular product doesn't belong on a convenient shelf if that shelf cannot safely support it.

Before allocating the fastest locations, rule out unsuitable ones:

• Products with temperature, security or segregation requirements need compatible storage.
• Bulky items may need a different route or handling equipment.
• Fragile products need access that doesn't invite crushing or repeated handling.
• Similar packaging needs clear identification and scanning controls; placing near-identical variants side by side may increase selection errors.

For dated stock, the pick arrangement must also support the operation's required stock rotation. Saving steps is no help if workers have to reach past newer stock to retrieve the correct lot.

Size the pick face around replenishment

The pick face is the location from which orders are picked. Reserve storage holds the stock used to refill it. Making every pick face small can create repeated refill trips during the busiest part of the day.

Suppose an accessory sells 180 units on a representative busy day, but its accessible bin holds only 60. Even if the bin starts full, two replenishments are needed to supply that day's 180 units. More may be necessary if demand exceeds the forecast or the initial quantity is lower.

The right answer might be a larger bin, a second controlled pick location, or replenishment before the rush. It depends on available space and how the system directs picks.

Plan a minimum quantity that triggers replenishment, who handles the task, and how long a refill typically takes. Keep that warehouse movement separate from purchasing decisions: reorder points for supplier stock solve a different problem.

Test companion products and congestion together

Products frequently bought together can be candidates for nearby locations. Check actual order combinations before grouping an entire collection by appearance or marketing category.

For example, a bottle and its replacement lid may share many orders. Placing them along the same picking route could help. Putting every bestseller in one narrow aisle could instead create queues when several workers arrive together.

Watch a normal busy period. Record where people wait, where replenishment interrupts picking, and whether carts block access. Distribute high-traffic locations when the resulting reduction in congestion outweighs a slightly longer route.

A second pick location needs system support, location-level quantities and clear replenishment ownership. An informal extra box under a packing table creates another place for stock to disappear from view.

Calculate the saving without overstating it

Consider this illustrative pilot, using measured task times across a comparable workload:

This estimate assumes the measured travel saving doesn't count the same shared route more than once. Include all workers involved in the extra replenishment time.

The result is 160 minutes of potential daily labour capacity, not an automatic payroll reduction or a promise of more shipped orders. The gain may be scattered across shifts. Packing, carrier collection or another stage may still limit output. Use a fulfillment capacity stress test to check whether the time can actually relieve the bottleneck.

Run a controlled move and review it

Start with a manageable group of SKUs and record the old locations. Count the stock, update the warehouse system, relabel the locations and verify a test pick before resuming normal work. Check both the vacated and new locations so stock isn't left in limbo.

Compare similar shifts before and after the move. Track total pick and replenishment minutes per completed order, selection errors, empty-bin interruptions and congestion. Separate one-time moving and training work from recurring operating time.

Keep the new arrangement when the combined results improve. Adjust it when shorter routes create more errors or refill work. Revisit the layout when promotions, product launches or order combinations materially change demand.

If you are reviewing a fulfillment partner's warehouse approach, contact 247 Fulfillment with your SKU list, product dimensions and representative order lines. Those details make a slotting discussion far more useful than total monthly order volume alone.