Bar shrinkage: how much is actually lost and how to detect it

Shrinkage is the difference between the amount of alcohol poured and the money collected for it. According to Diageo Bar Academy and BevSpot, in standard operations this ranges from 20-25 %. In a bar with monthly turnover of 500 000 Kč, this represents a loss of around 60-80 thousand Kč per month, and owners are mostly unaware of it.

Where shrinkage most commonly occurs

1. Overpour (largest share)

The jigger says 40 ml, but the bartender pours 45-50 ml. On a shot costing 80 Kč it looks harmless, but with 150 shots a day you lose 1 500-2 000 Kč. That is 45 000 Kč a month. The cause is usually habit or compromising generosity towards guests.

2. Unbilled drinks (35-40%)

A friend at the bar, personal consumption, "one to calm down". The bartender pours, the bottle empties, the till stays silent. This is internal theft, hardest to prove without continuous monitoring.

3. Spills and Returns

Poorly poured shot, guests preferred something else, cocktail failed. Total 2-5 % of turnover. Undetectable by standard inventory, looks like shrinkage, but it is legitimate loss. Only time-based records can distinguish one from the other.

4. Theft in deliveries

Less common, but it does happen. It can be verified simply by checking receipts against the bottles actually on hand. Digital inventory handles this automatically.

How to measure shrinkage

Traditionally, shrinkage is calculated weekly: you weigh the bottles, compare them with sales from the till, and convert the difference to ml. The problem is latency: an issue that started on Monday is only discovered on Sunday. And weighing 50 bottles once a week takes 3-5 hours of work.

Continuous monitoring via AI camera does the same in real time. Whenever bottle levels drop, the system logs it and pairs it with sales from the POS. A gap over 10% triggers an immediate alert, not a weekly inspection.

Typical pilot results

• First 30 days: Baseline collection without interventions. We measure actual shrinkage: typically 18-23 %.
• 30-60 days: Simply by bartenders knowing about monitoring, shrinkage drops to 10-14%. A psychological effect.
• 60-90 days: Specific alerts show when and where incidents occur. Targeted intervention reduces shrinkage to 6-8 %.

For a bar with a turnover of 500 thousand, the difference between 22% and 7% shrinkage is significant. 75 000 Kč per month - that is 900 000 Kč per year.

Pragmatic recommendations before deploying AI

1. Jigger calibration, every bartender has their own, and not everyone pours the same amount. A common standard and spot checks recover ~5 %.
2. Implement random stocktakes at least twice a week on 3-5 top movers (gin, vodka, premium rum) to increase vigilance.
3. Recording of claims and spillages as separate items in the till. Distinguishes legitimate losses from shrinkage.
4. Cameras only where they make sense, above the back bar and work surface. Insurance and basis for DPIA.

If shrinkage remains above 10 % even after these steps, it is time for continuous monitoring.

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