How To Design Your Warehouse Locator System

Winston Churchill once said: “We shape our buildings; thereafter they shape us.” How you design your warehouse locator system, pick flow and slotting strategy will profoundly impact your productivity throughout the building’s lifetime. It drives how cost, service and order quality define your business. Using colors and shape mnemonics in signage will produce immediate benefits.

So why do mispicks occur? It is usually a slight distraction, not gross mistake that offsets a picker train of thought. A casual conversation or looking ahead at their next pick often causes a slight miscalculation and a product is selected from a location directly next to, or above the target. Rarely do they mispick from a location cattycorner to the target.

There are clear trends that can be mitigated with simple visual hints that reinforce accuracy. What types of hints are effective?

Think how we learn things as children and eventually how we are trained on the task at hand. We have to acknowledge that we all learn differently. Some people learn best by reading documentation, others by observing and some by doing.

Most early learning tasks leverage this knowledge. Why are toy building blocks and xylophones colored and often numbered? While the true cause of some mispicks will continue to gray the hair of warehouse managers and remain a mystery, others can be diagnosed into continually replicated, common denominators. While pick methods vary by technology and equipment, the people factor can always be improved.

Consider a multi-layered approach that supports the basic numeric location (i.e. the “target” destination of pickers). This approach introduces a universal, second tier of location information using color and shape mnemonics. With modern label and printer technology, it’s a low cost solution that rivals RF, pick-to-light and voice directed picking technology in some environments.

So what are the contributing factors for a picker to be in the wrong place?

Attention and focus yes, but also signage. Poor signs or no visible locator map can get a new hire lost quicker than a sailor’s paycheck on shore leave. Good, clear signage improves picking accuracy. When you are driving in your car and lost, what information do you want from your GPS or co-pilot? The next turn! Do I go left, right or straight? Where is it? How far away is it? I need this information so I can start looking for it right away.

The quicker I know it, the faster I can travel until I arrive. Will my reference point be a building, street sign, traffic light? It seems simplistic, but walk through your operation with a new hire’s eye, and observe your signage. Can the building, zone or aisle signage be quickly identified? From all areas?

You’ll be surprised by the number of blind spots, especially within an aisle. Try asking an observant new hire to identify them vs. a trained staffer. How quickly can you see your next destination sign? How easy are the signs to distinguish? If they are all the same color and shape, it may translate to nothing less than camouflage to a new hire or someone with less than perfect vision.

Pick sequences can be a “directional beacon”, but how fast will the staff move if they are not very sure of when the next turn is? Some pickers work best from the numeric approach. Others have an affinity to colors, and others shapes. So why not leverage ALL three? Why do we so often choose only one?

Here are some helpful tips for both the slotting products and providing effective signage.


Store like items close, but not too close. You can reduce mispicks by up to 60% with thoughtful and non-contiguous slotting of the same style item. Store same vendor SKUS together to speed putaway, but use a “checkerboard” strategy to avoid horizontal or vertical assignment of SKUS that look alike or are different consumer sizes of the same item. Storing them adjacently confuses rookie pickers and fuels mispicks.

Speed picking and reduce fatigue. Most of you store high velocity items in your “Golden Zones”, but do you assign high velocity SKUs to ergonomically effective levels to avoid stretching and stooping? Do you do the opposite for slow movers by slotting them on low or high locations? Fatigue reduces quality and speed.


Use shapes and colors with large, bold fonts to identify all unique identifiers that add value. If you can’t produce colored or shaped labels with your current technology, there are several label and sticker companies like Smead, Avery, and Planetlabel that can provide pressure sensitive labels or stickers to support your signage efforts. Try doing a section a week to minimize constraints on your daily workload.

Use square labels for diamonds and boxes and then cut them in half for triangles.

Identify all “blind” spots, where the section is not clear and add signs as required.

Use simple forms of number sequences on labels and numbering system for your locator. It’s not a NASA project so don’t turn it into one.

Have clean copies of your locator map on posters, clipboards and picking carts to reinforce new hire learning and impress new visitors to your facility.

What’s your experience with picking and order quality? Please share your thoughts any ideas you have implemented that have improved your picking speed and reduced order errors.

Stephen G. Martin ( is an efficiency expert and a 30-year veteran in operations management.

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