Online grocery is no longer a side channel. According to NIQ and FMI, online sales now account for about one-fifth of total grocery spending. In 2025, eCommerce contributed close to 75% of the category’s dollar growth, while in-store sales stayed relatively flat.
That growth shows up on the warehouse floor. Orders arrive more often, with more lines and tighter delivery windows, and many distribution centers were designed for a different kind of order. Warehouse design is now one of the biggest levers a grocery operation has to keep up with demand.
The challenge is that online orders don’t behave like store orders. They’re smaller, more frequent, and expected faster, and that puts real strain on a warehouse built around pallets and full cases. The good news is that a lot of that strain can be solved without a bigger building.
The forecasts point in one direction. NIQ and FMI project U.S. online grocery sales will reach $452 billion by 2028, growing at an annual rate of 11.6%. The monthly numbers suggest the pace is holding. Brick Meets Click reported that July 2026 eGrocery sales rose 21.5% year over year while in-store sales fell 2.6%.
Shopper behavior matters as much as the totals:
Most grocery distribution centers were built to move pallets and full cases to stores, and that model works well when orders are large and predictable. Online orders ask for something different. They pull a wider range of products in smaller quantities and on tighter timelines, and the layouts that served store replenishment start to show their limits in these key areas.
When orders are built from broken cases and individual items, pickers touch more product on every order and cover more ground. Brick Meets Click reported that average order frequency rose 14.9% year over year in July, while delivery order values contracted, consistent with more orders carrying fewer items each. In a layout designed for full-case movement, travel and search time quickly become the largest share of the pick cycle, and every extra step is multiplied across thousands of order lines per shift.
Online assortments tend to expand faster than the space allocated to them, and new or seasonal products often arrive with little warning. A pick area slotted for last year’s product mix can become a bottleneck within months, because every new SKU needs a home that is close to the picker, easy to reach, and sized for its carton. Operations that can only re-slot by rebuilding racks end up choosing between crowded pick faces and long stretches of disruption.
Cooler and freezer square footage carries a premium to build and operate, so wasted space in those zones costs far more than in ambient storage. Pickers also move more slowly in the cold, and longer trips into those areas add up in labor and in the energy lost each time a door opens. Dense, well-organized pick faces matter more here than almost anywhere else in the building.
With short shelf lives and frequent orders, a slip in first-in, first-out (FIFO) handling rarely stays hidden in the back of a rack. It shows up as expired product, write-offs, or a customer who receives an item with less shelf life than expected. Layouts that depend on pickers and replenishment crews to rotate stock by hand leave plenty of room for those mistakes, especially during peak periods.
Each of these pressures traces back to how the space is laid out rather than how hard people are working, which is good news, because layout is something an operation can change. The principles below show where to start.
Most of the pressures above come down to the same question: is the warehouse built around where product sits, or around how product moves? Five principles help answer it.
Static storage treats a rack as a place where product waits. Online grocery fulfillment works better when the pick area functions as a flow system: product enters at the back, moves forward as it’s picked, and is replenished from a separate aisle. Separating picking from replenishment keeps pickers and replenishment crews out of each other’s way, which matters more as order frequency rises. Gravity-fed lanes, for cartons are the practical expression of this idea, since they keep the pick face stocked and rotate product in the right order without anyone touching it.
Many facilities use their floor space well but leave much of their cube unused. Pallet rack levels are often set for pallets and then hold lightly stocked product, leaving plenty of usable height between the beams. Building out takes capital and time, and demand is growing now. The least expensive space an operation can add is often the space already inside the building, especially in cold zones, where every cubic foot costs more. Look for solutions that integrate easily into existing racks and turn that unused height into pick faces.
Think of time in the cooler or freezer as a budget. Every minute a picker spends in the cold costs productivity, and every open door costs energy. The design goal is to concentrate product into dense, well-organized pick faces so each trip is short and each stop yields more lines. Fewer steps, less searching, and less reaching all shrink the time spent in those zones, and the savings repeat on every shift.
Most pick areas are slotted for the product mix of the moment, but a facility's mix in 18 months is hard to predict. A useful test is to ask how long it takes to move a SKU from one location to another. If the answer is a maintenance project, the layout is working against the operation. Storage that can be re-slotted quickly, without rebuilding the rack, turns SKU growth into a routine task and removes the need to forecast the future perfectly.
Labor is a major cost in any pick operation, and the way a pick face is built affects speed, accuracy, and how long people want to stay in the job. Product at comfortable heights, with minimal deep reaching and no need for step stools, helps pickers work faster with fewer errors. A logical, consistent layout also shortens training time for new hires, which matters in an environment with steady turnover and seasonal peaks. Ergonomics belongs in the design conversation from the start.
Two ideas run through all five principles: moving product by gravity so it flows to the picker, and packing more pick faces into space the operation already owns. Before looking at solutions, though, it helps to get specific about which of these matter most in your facility.
Principles are a useful starting point, but every operation has a different mix of constraints, and the right design depends on which ones cost the most today. A cold chain distributor fighting for freezer space faces a different problem than a regional grocer whose SKU count has doubled, even though both are feeling the same online growth. Taking time to diagnose the operation before changing anything helps avoid solving the wrong problem, or adding capacity in one area while the real bottleneck sits somewhere else.
The questions below are a good place to start. They work best when the people closest to the floor help answer them, including pickers, replenishment crews, and shift supervisors, since they often know where time is being lost long before it shows up in a report.
The answers show whether the priority is flow, density, or flexibility, which points to the right solution.
The design principles above keep pointing back to the same two ideas: let gravity move product to the picker, and fit more pick faces into existing space the operation already owns. That’s where UNEX solutions come in. SpanTrack carton flow and Pallet Track pallet flow were engineered around exactly those ideas, and they work inside standard pallet rack, so grocery operations can add capacity and speed without starting over on the building.
The right fit depends on what and how you're picking. SpanTrack is best suited for medium- to fast-moving case picking and each picking applications. Pallet Track is best suited for very fast-moving SKUs that are better off being picked directly from pallets to avoid double handling. Both solutions deliver significant savings in space, time, and cost by reducing travel time, minimizing unnecessary handling, and making picking operations more efficient.
SpanTrack is an engineered-to-order carton flow solution that drops into new or existing pallet rack, with no shelves or intermediate supports required. Product loads from the back and flows by gravity to the pick face, supporting FIFO rotation and keeping the face stocked.
Grocery operations have put this to work. FreshDirect, which serves about 63,000 orders per week, added 500 SKUs in one year while improving pick rates. A wholesale distributor in a freezer held at -10 degrees created a pick area six times denser.
Not every product belongs in carton flow. For the fastest movers, picking straight from pallets avoids the double handling of breaking a pallet down and loading it into carton flow. Pallet Track keeps those pallets organized and moving seamlessly to the point of pick. It is dynamic storage for pallet positions that loads pallets from the rear and removes them from the front, creating a first-in, first-out system that increases storage density.
Together, SpanTrack and Pallet Track allow grocery operations to match their storage and picking systems to SKU velocity, keeping high-volume products moving efficiently while maximizing space and reducing unnecessary handling.
Online grocery growth continues to put pressure on how distribution centers are designed and operated. Grocery operations that leverage gravity flow, maximize vertical space, and maintain flexible picking configurations will be better positioned to handle increasing order volumes, improve efficiency, and make better use of existing space without expanding their facilities.
Contact UNEX today to learn how SpanTrack carton flow and Pallet Track pallet flow can help your grocery operation increase capacity, improve picking efficiency, and adapt to growing online demand.