A mispick happens at the shelf, during order fulfillment, when a picker or a machine pulls stock for an order. What happens next depends on where it is found. A picker who notices it fixes it on the spot; a check at packing sends the order back for a re-pick; a mispick that slips past every check ships to the customer. Researchers at the Technical University of Munich (TUM) put it plainly in a study of picking errors: the later an error is found, the heavier its consequences.
Types of Mispicks
A mispick takes one of three forms. Each has a check that catches it:
- Wrong item. A different product is picked in place of, or as well as, the right one. Scanning the item's barcode against the order catches it.
- Wrong variant. The right product in the wrong size, color, flavor or pack size, often a look-alike from the next slot. It has its own stock keeping unit (SKU), so a barcode scan catches this too.
- Wrong quantity. Too many or too few units of the right item, including a whole line skipped. Confirming the count at the location, or weighing the finished order against its expected weight, catches it.
A mispick is not the same as a packing error, where the right items go into the wrong box, or a shipping error, where a correct order goes to the wrong address. All three can end with a customer who did not get what they ordered, but each has a different fix.
How to Calculate the Mispick Rate
Divide the mispicked order lines by the total lines picked in the same period and multiply by 100. Pick accuracy is the other side of the same number: 100% minus the mispick rate.
Two choices change the result, so agree on them before comparing numbers. First, count by line or by order: one wrong line in a five-line order is one mispicked line out of five, but one mispicked order. Second, count every mispick found, at the shelf, at the packing check and by the customer, or the rate measures only the errors that got away. A rate built only from customer complaints measures something closer to order accuracy.
What Causes Mispicks?
- Look-alike products side by side. Variants of one product in near-identical packaging, stored in neighboring slots, are the classic trap.
- Inaccurate inventory records. When the system says a slot holds one SKU and it holds another, the picker is sent to the wrong stock.
- No scan at the pick. On paper pick lists, the picker's eyes are the only check.
- Unclear locations and labels. Worn or missing labels, and location codes that are easy to misread, send pickers to the wrong slot.
- Speed pressure and fatigue. Pick-rate targets that reward speed alone, long shifts and peak-season volume all raise the error rate.
- New or temporary staff. Pickers who do not yet know the products confuse variants more often.
How Warehouses Catch and Prevent Mispicks
- Scan the location and the item. A warehouse management system (WMS) with handheld scanners checks each pick against the order before the picker moves on.
- Guide the picker. Pick-to-light lights the right slot and shows the quantity. Voice picking directs the picker by audio and has them confirm each pick by voice; the TUM study notes that spoken check digits can confirm that the right article or the right quantity was taken.
- Weigh the order at packing. A scale compares the packed order with the weight the system expects from its items. The TUM study notes that check-weighing works when the item weights are in the WMS and the products differ enough in weight; it can then catch skipped lines, wrong quantities and many wrong items.
- Slot look-alikes apart. Slotting optimization separates products that are easy to confuse, so a reach into the neighboring slot finds something obviously different.
- Keep inventory records right. Cycle counting catches slot errors before they send a picker to the wrong stock.
- Check before shipping. A quality control (QC) check at packing, by a second person or a scan of every item, stops a mispick from shipping.
- Trace each mispick to its cause. Logging every mispick by product, location, picker and shift shows whether the fix is a slot move, a label, training or a missing scan.
More checks cost time, so the right level depends on what an error costs. The TUM study concludes that a 100% check aimed at zero picking errors is not worth it for every operation.
What a Mispick Costs
A mispick caught at the shelf costs a few seconds. One caught at packing costs a re-pick and, if the wrong item has left its slot, a putaway and an inventory correction. One that ships costs the most when the customer finds it: customer service time, a return, a replacement shipment, often by a faster service, and a customer who may not order again. If the returned item cannot be resold, it is lost too. Our guide to ecommerce returns management covers how a returned wrong item is received and restocked.
If a 3PL picks for you, ask how it counts mispicks, by line or by order and at which check, and what accuracy figure its contract or service level agreement (SLA) commits to.