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Order picking
Order picking is retrieving products from storage to fill a specific customer order. It is the most labour-heavy job in most warehouses — estimated at as much as 55% of total warehouse operating expense. Pickers work order by order, in batches, by zone or in waves, and the choice decides how far they walk.
Four methods
| Method | How it works |
|---|---|
| Discrete | One picker picks one order at a time |
| Batch | One picker picks several orders in one tour, by article |
| Zone | Each picker picks the part of the order in an assigned zone |
| Wave | Orders are released together for picking in several areas |
The review defines picking as retrieving products from storage, or buffer areas, in response to a specific customer request, and estimates its cost at as much as 55% of total warehouse operating expense; the Georgia Tech textbook traces the figure to Frazelle's work in the 1990s. OSHA's warehousing guidance targets the physical load: it suggests reducing case weights to 35 pounds or less, and placing high-volume items near standing elbow height — the same rule behind the golden zone in slotting.
Worked example: picking labour for one day
1,200 order lines a day ÷ 30 lines an hour = 40 picker-hours · at 77.4 lines an hour ≈ 15.5 picker-hours30 lines an hour was the median and 77.4 the best-in-class threshold in WERC's 2011 benchmark, as reported by DC Velocity; the 1,200 lines are illustrative.
The mistake people make
Choosing a picking method by habit. A warehouse of small e-commerce orders run discretely sends a picker the length of the building for each one; a warehouse of full-pallet orders run in batches gains nothing. Match the method to order size and the truck schedule, then slot the stock to suit it. Measure lines picked per hour before and after the change.
FAQ
Order picking: common questions
- What is the difference between batch and wave picking?
- Batch picking groups several orders into one picking tour. Wave picking releases a set of orders at the same time across several areas, usually so they are ready for the same dispatch.
- What is a good pick rate?
- It depends on the product and the method. In WERC's 2011 benchmark the median was 30 lines an hour, and best-in-class warehouses picked 77.4 or more.
- Why is order picking so expensive?
- Because it is labour, and most of that labour is walking — about half of a picker's time in the typical split the de Koster review gives. That is why picking can be as much as 55% of warehouse operating expense.
Sources
- Design and control of warehouse order picking: a literature review — de Koster, Le-Duc and Roodbergen, European Journal of Operational Research, 2007
- Warehouse & Distribution Science, release 0.98.1 — Bartholdi and Hackman, Georgia Tech, 2019
- Warehousing: hazards and solutions — OSHA
- DC Measures 2011, the annual metrics study — DC Velocity, 14 March 2011
Related terms
- SlottingTerm
- PutawayTerm
- Warehouse management system (WMS)Term
- On-time in-full (OTIF)Term
- Cross-dockingTerm
On Traqo: 3D Load Planner shows how every box and pallet fits inside the truck before dispatch.