Velocity-based slotting is not enough: the case for affinity slotting

Warehouse slotting refers to where you place items within your warehouse layout. Most WMS implementations recommend "velocity-based slotting" — placing high-rotation items near the dispatch dock and slow-rotation items in the back.

While this is a step up from random layout, it misses a massive source of efficiency: affinity.

The Case for Affinity Slotting

Affinity slotting analyzes invoice history to group items that are frequently purchased together.

For example, if clients who buy item A also buy item B 85% of the time, placing item A at the front of aisle 1 and item B at the back of aisle 5 forces your pickers to walk the entire warehouse length for a single order. Placing them in adjacent bins saves kilometers of walking distance.

By implementing affinity-based slotting in a regional 3PL warehouse, picker walk distances were reduced from an average of 11 km to 4.2 km per shift, doubling pick rates without adding extra staff.