What is Order Picking? - Importance, Systems, and Best Methods

Last Updated: June 30th, 2022
Researched and Written by: Russ Davidson

Order picking is one of the most critical tasks in warehousing and supply chain management. If you can’t quickly and efficiently find the right product in your warehouse, your entire operation will lag behind in fulfilling orders, and your reputation as a distributor will suffer. Whether you’re looking to streamline an existing system or implement new warehouse management software from the ground up, these tips will get you on track for success.

Warehouse operations include receiving inventory, putting the inventory away, moving inventory around the warehouse for increased efficiency or for a first-in-first-out strategy (FIFO), and picking orders for shipment. When you understand the components of warehouse operations, you can better understand why order picking is so important.

Order picking is not just a manual activity and tends to be automated through specific order picking methods. If you want your warehouse to run smoothly, you need to find the right order-picking solutions. However, given a large number of methods available, you need to review the pros and cons of both.

Note: The picking techniques detailed in this post are simplified and distilled down to the basics. In practice, most high volume environments won’t employ a single picking method, but instead combine a hybrid of methods.

What is Order Picking?

Order picking is the process by which warehouse workers pick the individual items to satisfy the fulfillment of a customer’s order. Order picking is part of the order fulfillment process. The term “picking” refers to the practice of manually selecting items from inventory. Order picking is distinct from order packing. Workers who pick orders manually scan items and place them into boxes and then put those boxes on pallets. In contrast, workers who pack orders select items first and then put those items in boxes or bags.

In fulfilling a customer order, the process needs to have little to no bottlenecks in order to ensure the customer receives their items by the guaranteed delivery date. The order-picking order and instructions are usually managed by a WMS, but can also be purchased as a standalone warehouse order-picking software.

Why is a Warehouse Order Picking System Important?

Order picking is an important and critical part of warehousing operations because it helps fulfill customer orders. If you can’t quickly and efficiently find the right product in your warehouse, your entire operation speed slows down and begins to impact the delivery time of a customer’s order. To ensure that your warehouse runs smoothly and efficiently, you need to find the right order picking process that can pave the way towards automation.

With the volume of order-picking strategies that exist, it’s important to focus on ones your business can easily implement, increase efficiency, improve order accuracy, and simultaneously boost customer satisfaction.

One important thing to remember is that order picking is not just a manual activity. When you understand the components of warehouse operations, you can better understand why order picking is so important. This is because warehouse operations consist of:

  1. Receiving inventory
  2. Putting the inventory away
  3. Moving inventory around the warehouse
  4. Picking orders for shipment

Each of these activities is important, as they support one another and work together to create an efficient warehouse operation. If just one of these operations is not done well, the entire supply chain suffers.

Discrete Order Picking

Discrete picking is one of the most common types of order picking. It is a manual order picking method that is focused on picking one item at a time from specific locations.

Discrete picking is also referred to as single order picking, individual order picking, or piece picking. In this method, a picker goes through one order at a time, grabbing an item line by line before moving on to the next order.

Single-order discrete picking diagram
Simple example workflow of a single order pick.

Discrete order picking is often used in distribution warehouses where products are stocked in aisles and cartons/bins and sorted by SKUs and/or serial numbers. Warehouses that utilize discrete picking often use barcode scanners to scan items. This helps the warehouse workers quickly pick the right items for an order.

When order volume becomes high, the most common bottleneck in order throughput is picker walking time. Most warehouses using discrete picking have computerized picking and putaway systems. This makes the picking process more efficient. It also helps the warehouse workers know what to pick and from where.

According to a now-famous study, a Dutch distribution center obtained a “reduction between 17 and 34% in walking time, by simply routing the pickers more efficiently.” Further reduction can be made by clustering orders and optimizing warehouse layouts.

Batch Order Picking

Batch picking can also be referred to as consolidated or multi-order picking. With this method, a single picker grabs items with the same SKU for multiple orders at the same time. Batch picking is best for high order volumes with a high rate of shared SKU overlap.

Multiple order batch picking diagram
Example workflow of a consolidated order batch pick.

Batch picking is very similar to discrete order picking in terms of the process and types of warehouses that use it. The main difference between discrete and batch order picking is the types of orders each method is used for.

Batch order picking can be used for lots of different types of orders. However, batch pickers usually pick orders that are all similar. For example, batch order picking is often used to pick orders that contain a mix of items from multiple bins. Batch order pickers select items and put them in batches. Then the batches are put on pallets and moved to the shipping area.

Batch order picking is often used for products that are not labeled. For example, batch order picking is used for bulk items where each unit is not marked with an individual lot or bin number.

Zone Order Picking

Zone picking is typically more expensive than batch. With zone picking, SKUs are divided into separate areas, or zones. Each picker is assigned to pick from a single zone per shift.

If an order requires items from multiple zones, an order box moves down (often using a conveyor) to next zone. This is also called “pick and pass” or “sequential zone picking.”

Single order sequential zone picking diagram
Simple example of a single order workflow in sequential zone picking.

Zone order picking is another common order picking method. Zone picking is often used in warehouses where products are organized by product type. Many warehouses that use zone order picking organize products into product zones, or pick zones. Then, the items in each zone are stored in specific areas of the warehouse.

Warehouses that use zone order picking have pick guides. Pick guides are used to help the warehouse workers quickly find the right items for the orders they are picking. Many warehouses that use zone order picking have computerized picking and putaway systems via inventory management software or WMS systems–which make the picking process more efficient. It also helps the warehouse workers know what to pick and where to put things once they are picked.

Single order simultaneous zone picking diagram
Simple example of a single order workflow in simultaneous zone picking.

Some warehouses that use zone order picking have existing shelving or are currently installing a new warehouse management system (WMS) and are looking for optimal efficiency while lowering operating costs. This helps increase the likelihood of the following benefits:

  • Reduced picker congestion in high-volume environments.
  • Instead of a “pick and pass” zoned system, each zone can be picked at the same time. This is called “pick and merge” or “simultaneous zone picking.”
  • In simultaneous zone picking, parts from each zone are consolidated at a packing station (rather than one at a time via a conveyor belt).
  • The parallel nature of pick and merge can often lead to faster order fulfillment than other methods.

Wave Order Picking

Wave picking is conceptually similar to batch picking. Like batch picking, ordered items are queued and grouped (batched) into combined pick lists.

Wave order picking is another type of manual order picking method, which occurs when the warehouse workers use a sort of assembly line to pick and put away items. This method is often used in warehouses that have large-scale operations.

Wave order picking is often used with sophisticated warehouse systems. This helps the warehouse workers know what to pick and where to put things (pick locations) once they are picked. Wave order picking is often used in warehouses with lots of pallets. It is also used in warehouses that store items in bulk bins.

Traditionally, batch picking is done once per day and solely focused on maximizing the amount of product overlap between orders. Wave picking, on the other hand, is executed multiple times per day (or shift) and balances more factors than product overlap.

In addition to maximizing product overlap, wave picking balances pick list capacities, product weight, shipping schedules, worker shifts, and more, in order to avoid picking errors.

Cluster Order Picking

Cluster picking is a method of order picking that groups orders together so that one employee can pick multiple orders at the same time. This reduces the amount of time an employee needs to spend at each station and increases their speed.

Cluster picking helps pickers fulfill multiple orders without intermixing the orders–letting each warehouse worker put the items into boxes or totes in order to keep the orders separated. This process begins once multiple orders have been assigned to an order picker. Labels are attached to each container, tote, or box. These labels are generated by the warehouse management software that helps cluster the orders into the most efficient and most likely to be fulfilled from a single location.

The biggest advantage of cluster order picking is that orders can be satisfied in bulk, mostly because the material handling done by the order picker simultaneously organizes the picked items into their appropriate shipments. There is no need to further parse through the collected SKUs later on to “build” the orders.

Comparison Table

In reality, the comparison below is simplified. Typically in high order volumes businesses will employ hybrid models i.e. a combination of batch and zone, allowing pickers to pick multiple orders at a time for each zone.

Discrete Batch Zone
Complexity Very low Mid High
Cost Low Mid High
Picker Walk Time Highest Low Mid
Order Throughput Low High Very high
Fulfill speed Slow Slowest Mid (sequential), fast (simultaneous)
Best For Low order volumes, large/heavy products High order volumes with common SKUs High order volumes, alleviate picker congestion, multiple daily ship deadlines (simultaneous)
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