Order Picking Methods Compared: Which One Fits Your Warehouse?

Picking is where a warehouse spends much of its time. Pickers walk, search, reach, and carry, and every metre of unnecessary walking is paid for in wages. Two warehouses with the same stock and the same orders can differ widely in how much effort it takes to fill them, simply because they pick in different ways.

There is no single best method. The right one depends on how many lines each order has, how big the building is, how many people pick at once, and when the carrier collects. This guide describes five methods, works through a walking-time example, gives you six questions to choose with, and explains what a system adds.

The Five Methods

1. Discrete picking (one order at a time). One picker takes one order and collects every line.

• Best when: orders are few, large, or urgent.

• Watch out for: a lot of walking when many small orders are picked one by one.

2. Batch picking. One picker collects several orders’ items in a single trip, then the items are sorted into orders.

• Best when: orders are small, often a line or two, and many contain the same products.

• Watch out for: the sorting step, which can cancel out the walking saved.

3. Zone picking. The warehouse is split into zones. Each picker stays in a zone and picks the lines for that area, then the order moves on.

• Best when: the building is large and the range is wide.

• Watch out for: queues in a busy zone, and the need to bring partial orders together.

4. Wave picking. Orders are released in groups, or waves, timed to carrier cut-offs or packing capacity.

• Best when: dispatch follows fixed schedules, such as courier collections.

• Watch out for: a rigid schedule, because a late order can miss its wave.

5. Cluster picking. A picker collects several orders at once into separate containers on one cart, so there is little sorting afterwards.

• Best when: orders are small and a cart can hold several containers.

• Watch out for: mix-ups between containers, which scanning can reduce.

A Worked Example: Walking Time

Suppose 20 small orders must be picked, each from a different part of the warehouse. Assume a picker walks at about 4.5 km an hour, or 75 metres a minute.

• Discrete: each order is a separate trip of about 120 metres, so 20 × 120 = 2,400 metres, or 2,400 ÷ 75 = 32 minutes of walking.

• Batch: four orders per trip means five trips. Each trip is longer, at about 160 metres, so 5 × 160 = 800 metres, or 800 ÷ 75 = about 10.7 minutes of walking.

• Sorting: at 0.5 minutes per order, 20 × 0.5 = 10 minutes.

• Total for batch: 10.7 + 10 = about 20.7 minutes, against 32 minutes for discrete.

Batch picking saves about 11.3 minutes, or 35%, but nearly half of its time goes on sorting. If sorting took 1.5 minutes per order instead, the total would be 10.7 + 30 = 40.7 minutes, slower than discrete picking. The figures are illustrative, so time your own trips.

Six Questions to Choose With

1. How many lines does a typical order have? One or two lines point towards batch or cluster picking.

2. How large is the building? A big site with a wide range points towards zone picking.

3. How many pickers work at once? Several pickers in one aisle can queue, which zone picking can make worse.

4. When does the carrier collect? Fixed cut-offs suit wave picking.

5. How much space is there for sorting or packing? Batch picking needs a sorting area, so check that one exists.

6. How accurate must picking be? If mix-ups are costly, favour methods with scanning at each step.

Mixing Methods

Most warehouses combine methods. A common pattern is zone picking for a large building, batch picking within each zone for small orders, and wave release to match courier collections. Start with one method for one class of orders, measure the result, and add others only when the numbers justify them.

Common Picking Mistakes

• Using one method for everything. A method that suits small orders can be slow for large ones.

• Skipping the scan. Without confirmation at the shelf, errors are found by customers.

• Mixing methods in the same aisle at the same time. Batch pickers and discrete pickers can block each other.

• Never measuring. Without trip times and error counts, a change in method is a guess.

What a System Adds

Picking methods are easier to run when software directs the work:

• Pick lists are generated in an efficient sequence.

• Orders are prioritised by urgency, location, and picker availability.

• Scans confirm each pick against the order.

• Different roles see only the tasks that are theirs.

• Pick times and error counts are recorded, so you can compare methods.

For teams that want software to direct this work, HashMicro warehouse picking software supports batch picking operations, receiving notes, and delivery order management, with barcode scanning across stock movements. Features differ by version, so ask to see it handle your own orders.

A demo test is simple: give each vendor 20 real orders and ask it to generate pick lists under two different methods. Compare the routes, the number of scans, and how the orders are brought back together.

Singapore Notes

• Tight space: where floor space is expensive, aisles are often narrow, so zone picking can create congestion in the same aisle. Plan pick paths to avoid it.

• Multi-level sites: lifts and ramps add time that a flat distance estimate ignores, so include them when you time trips.

• Peak dates: a method that works on an ordinary day may struggle during a sales peak, so test it with a peak-sized batch.

Match the Method to the Order

The best picking method is the one that matches your order profile, and the profile changes as you grow. Time your current trips, test one alternative on a small set of orders, and keep the one that is faster without raising errors.

If you are comparing systems that can direct several methods, a guide to warehouse management systems in Singapore is a useful place to start.