The shelf says fifty. You count thirty-two. It probably did not walk out in one go. More often it leaves a little at a time: a supply used chairside and never logged, a return that went back on the shelf without a scan, a count that was close enough last quarter so nobody checked it again. Now the number you order from, calculate costs from and plan from is wrong, and you only found out because you happened to look.
You are not the only one. In a study of nearly 370,000 inventory records across 37 stores of one retailer, 65 percent of the records did not match what was physically on the shelf (DeHoratius and Raman, Management Science).
Why the number drifts
The system only knows what someone tells it. Every time stock moves without a record, the count on the screen and the count on the shelf move apart. The usual causes are ordinary, not dramatic:
- Items used or pulled during a busy day and never written down.
- Returns and swaps put back without being entered.
- Deliveries received short, or counted as cases when the system expects single units.
- Counting mistakes. Lightspeed's guide for retailers says most stock gaps come from errors during the count itself, like bad math or a typo, with theft and receiving mistakes as other causes (Lightspeed).
Each one is small. They add up because nobody checks often enough. A restaurant guest column in Restaurant Dive makes the point plainly: if you count once a month, you have no way to tell when during the month the problem began (Restaurant Dive).
What the gap costs you
When the shelf is short, a wrong count costs you twice. First, the missing stock itself. Second, the decisions you make from the wrong number. Researchers who modeled this found that even a small rate of loss the system never records can throw off reordering and leave items running out, and the sales lost when they run out can far outweigh the stock that went missing (Kang and Gershwin, IIE Transactions).
It also bends the numbers you read every month. The same Restaurant Dive column shows that a $500 miscount on a $75,000 month moves food cost by about two-thirds of a percentage point. You could be chasing a price problem that is really a counting problem.
And it is not only restaurants. The American Dental Association calls supply management one of the easiest targets for abuse because most dentists are too busy to watch what is ordered, used or "going out the door" (American Dental Association). One optometrist wrote that she believed her practice held about 1,000 frames and found close to 2,000 when she looked (Review of Optometric Business). The gap runs both ways.
A short count you can run this week
You do not need a full count to learn whether you have a problem. Start with the items that make up a large share of what you spend. In restaurants, for example, Restaurant365 notes that roughly 20 percent of items make up about 80 percent of the cost of goods sold (Restaurant365). Start there.
- Pick the three items you spend the most on each month. Proteins in a kitchen, implant or ortho supplies in a practice, top frame lines in an optical, your best sellers in a shop.
- Print or screenshot what the system says you have of each, right now.
- Count every place the item is kept: shelf, stockroom, cooler, treatment room or second location.
- Count between deliveries. If a delivery is already entered in the system, count it too, even if it is not put away yet.
- Count in the same unit the system uses. Singles against singles, cases against cases.
- Write the gap for each item, in units and in dollars.
- Do it again next week, same day, same way.
Illustrative: a two-location restaurant group counts brisket, salmon and ribeye on a Monday. Two items match within a pound. Salmon is short 18 pounds at one location only. That points to one kitchen and one item, not the whole company, and now the owner knows where to look first.
When the gap is real
One bad count can be a counting mistake. Count the item again, carefully, before you do anything. Check the unit, check partial containers, check whether a delivery landed in the wrong week. If the gap shows up again after a careful recount, treat it as real and trace where it happens. The question changes from "how much" to "where."
Walk the item's path: how it arrives, where it is stored, who uses it, how returns come back. Look for the handoff where the record gets skipped. Then keep counting those few items weekly. The same study that found 65 percent of records wrong also found that stores with stronger auditing practices tended to have more accurate records (DeHoratius and Raman).
Questions owners ask
How often should I count?
The Restaurant Dive column suggests your highest-spend items weekly and a full count at month end. Lightspeed suggests short rotating counts through the year, for example a few short counts every day, so gaps show up within days instead of months.
Does a gap mean someone is stealing?
Not on its own. Unlogged use, receiving mistakes and counting errors all create the same gap. Recount and trace the item's path before you draw a conclusion.
What if my system is right?
Good. Now you can trust the number you order from. Keep the weekly count so you find out early if that changes.
If you want to see where else money may be slipping without anyone noticing, take the free 2-Minute Gap Check.