Symbotic's software figures out the best possible order to stack products onto a shipping pallet — factoring in which items are fragile, how heavy they are, what store aisle they belong to, and dozens of other rules — then directs two robot arms to build the pallet at high speed. If something goes wrong mid-build, the system recalculates the entire plan in seconds without stopping.

The palletization algorithm evaluates an enormous number of possible stacking sequences to find the one that maximizes pallet density while respecting constraints including crushability, allergen separation, caustic materials, center of gravity, and store planogram layout (grouping items by store aisle and department). Two robotic arms on opposite sides of a pallet work in tandem, placing a case every three seconds or less. The result is pallets that are 30–50% denser than manually built ones, at a throughput of 1,350 cases per hour per outbound cell pair. When an anomaly occurs — for example a case placed incorrectly — the system uses real-time replanning to recalculate the remaining sequence without interrupting the pallet build.