Slotting

Slotting is the process of determining the optimal storage position for each item in a warehouse. The goal is to minimise picker travel time, reduce handling effort, and maximise space utilisation. High-velocity items are placed in ergonomic, easily accessible positions (golden zone at waist to chest height). Heavy items go at floor level. Slow movers are assigned to higher or more remote locations.

In a warehouse with thousands of SKUs, poor slotting can add kilometres of unnecessary walking per shift. Studies show that travel time accounts for 50 to 60 percent of a picker's working hours in an unoptimised warehouse. Proper slotting can improve picking productivity by 10 to 30 percent without any additional investment in automation or labour. It is one of the highest-return optimisation activities available.

Demand patterns change seasonally, with promotions, and as product ranges evolve. A static slotting assignment becomes suboptimal over time. Regular re-slotting — typically quarterly or after major range changes — uses updated pick frequency data to reassign locations. A WMS can recommend re-slotting moves and schedule them during off-peak hours to minimise disruption to normal operations.