Picking orders

Picking is usually the biggest cost in a warehouse, because it's done by hand and involves a lot of walking. How you organise it makes a big difference.

In discrete picking, one picker takes one order at a time, walking the aisles until it's done. It's simple and hard to get wrong, but slow when orders are small. Batch picking has one picker collect several orders in one walk, usually with a cart split into a tote per order, so the walking is shared.

Zone picking gives each picker one area of the warehouse. An order passes from zone to zone (often on a conveyor) and each picker adds the items from their zone. Wave picking releases orders in groups at set times, timed to when each carrier's truck leaves, so the right orders are ready for the right truck.

Pickers are measured by pick rate: order lines picked per hour. If a shift needs 3,600 lines picked in 8 hours and a picker does 150 lines an hour, that's 3,600 ÷ (150 × 8) = 3 pickers. Accuracy matters as much as speed: a wrong item means a return, a re-ship and an unhappy customer.

A warehouse management system (WMS) runs all of this: it knows every location, tells pickers where to go in the shortest order, and checks each scan. Barcodes are scanned one at a time; RFID tags can be read by radio, many at once and without a line of sight. Goods-to-person systems go further: robots bring shelves or totes to a picker who stays in one place.