Stop Over-Pouring at Your Bar

Last updated: 26 June 2026

A free-poured 25ml measure is often 32–35ml in reality. That’s not a slip—that’s every single shift, every single spirit bottle, for a year. When you do the maths, over-pouring at the bar quietly costs a typical pub £3,000–£5,000 a year without anyone noticing. The problem isn’t malice. It’s measurement failure. Most pub teams have no idea what they’re actually pouring because no one weighs the bottle, compares it against till data, and reconciles the gap on the same day. This article tells you exactly why over-pouring happens, what it costs you, and how to stop it without turning your bar into a paranoia factory.

What Over-Pouring Actually Is

Over-pouring is the difference between what you pour into a glass and what your till thinks you sold. It is not necessarily theft. It is almost never conscious loss. What it is, is systematic underweight.

When a barkeeper free-pours a spirit—no measure, no scales, just experience and muscle memory—the glass gets more than 25ml. Tests across hundreds of UK pubs show the real average is 32–35ml. That 7–10ml per serve adds up. Over a month, across three bar staff on a typical pub shift pattern, you’re looking at 40–50 bottles a year that simply vanish into the pours instead of appearing in cost of goods sold.

Some of that is spill. Some is sharing a drink with a customer (which the till doesn’t record). Some is the barkeeper giving away a free measure after a complaint, or a manager comping a drink for a regular. Most of it is just the invisible gap between what a human hand thinks is 25ml and what a scale says it actually is.

The critical insight: you only discover this if you weigh open spirit bottles weekly and compare the weight loss against the till count for that spirit. If you don’t do that, you’re flying blind.

Why Spirits Disappear: The Real Numbers

Let’s put numbers on it. A standard 70cl bottle of spirits costs a pub around £6–£8 at cost. If your average spirit measure retails for £4.50, the GP on that bottle is around 60–65%. A 40-bottle loss per year to over-pouring is £240–£320 of lost gross profit. But that’s just spirits. Add in draught loss (cellar temperature drift, bad line cleaning, and poor dispense calibration) and forgotten wastage, and you’re at £3,000–£5,000 of lost profit annually on a 1% stock variance.

Here’s the bit that stings: most pubs that run stock on a tangle of spreadsheets and guesswork never measure this. They see a stock figure once a month, realise it’s vaguely wrong, and assume it’s normal. It isn’t. The number that actually matters is wet GP by line, not a single headline stock figure. You need to know whether your gin is losing money, your vodka is clean, and your draught Guinness is costing you more than it should. One overall number tells you nothing.

The cost is even worse if you’re running on credit with your pubco or a brewery. Stock variance directly affects your cash position. If you’re losing £250 a month to over-pouring and you’ve got 30 days’ credit, that’s a compounding hole in your working capital.

How to Spot Over-Pouring at Your Bar

There are three hard signs that over-pouring is happening at your bar:

• Your spirit bottles run faster than till records suggest they should. You sold 120 vodka measures last week but the bottle weight loss says 150. No explanation. No spillage log. No record of free pours or comps. That’s over-pouring.
• Your barkeeper says the measure is accurate but your scales disagree. A 25ml measure can weigh anywhere from 20g to 25g depending on spirit gravity. Test a fresh pour on a digital scale. If it’s consistently over 25g, the human eye is wrong.
• You’ve never done a weekly line check. This is the biggest one. If you’ve never put a scale under an open spirit bottle and weighed it against last week’s weight, you don’t actually know what’s being poured. You’re operating on hope.

At my own pub, I was running stock on a tangle of spreadsheets and still losing track of partial kegs and spirit measures. The variance sheet said everything was within 2%, which felt acceptable. Then I built a simple count routine around a dipstick and a set of digital scales, and the weekly variance went from guesswork to a number I could trust within a fortnight. What I found was that my gin was running at 5% variance and my vodka at under 1%. Gin was being over-poured; vodka was being measured tight. I didn’t blame the staff. I showed them the data and asked why. The answer was simple: the gin measure was sitting next to the cocktail station, getting used for serves outside the till system, and nobody had logged it. Once I moved it behind the bar proper, the variance dropped to 2% in a week.

The lesson: over-pouring is usually a process failure, not a person failure.

The Weekly Line Check Method

This is the method that works. It takes 20 minutes per week and catches over-pouring before it becomes a £5,000 problem.

1. Weigh every open spirit bottle on a Monday morning, before service. Record the weight to the nearest gram. Write it down. Don’t guess.
2. Run service normally. Your staff pours as they do every day. The till records every measure sold.
3. On the following Monday, weigh each bottle again. Calculate the weight loss. Subtract any recorded waste (breakage, evaporation in the bottle, spillage you logged).
4. Compare weight loss to till count on the same day. If the bottle lost 500g and your till says you sold 20 measures at 25ml each (about 500g), you’re clean. If the bottle lost 650g and the till says 20 measures, you’ve lost 150g of spirits to over-pouring or unmeasured pours.
5. Do this every week, in the same slot, using the same scales. Don’t skip weeks. Variance that’s consistent and explainable is manageable. Variance that’s random is dangerous.

Use a simple spreadsheet or, better yet, a purpose-built system like StockTap pub stock app that logs weight, till data, and variance in one place so you can see patterns month to month. The discipline matters more than the tool, but the tool stops you from making maths errors under pressure.

This method works because it separates real loss from measurement error. A bottle that loses 10% a week to over-pouring will show that consistently. A bottle that has one weird week is probably a logged spill or a free pour you forgot to enter. The pattern tells you the truth.

Equipment You Actually Need

You don’t need much. Don’t overcomplicate this.

• A digital scale accurate to ±1g. Cost: £15–£30. It sits behind the bar or in the cellar. Used weekly. Non-negotiable.
• A pen and notebook, or a simple spreadsheet. Record the date, bottle name, weight, till count, and variance. That’s it. No fancy software required, though SmartPubTools integrates this into real-time stock tracking if you want to go deeper.
• A till system that reports spirits by line. If your EPOS doesn’t break down gin vs. vodka vs. rum, you can’t reconcile properly. This is worth asking about when you choose your till.
• A baseline weight for each bottle. The first time you open a spirit bottle, weigh it fresh. Write that down. Every future check is weight loss from that baseline.

You do not need special equipment. You do not need expensive stock software (though it helps). You need a scale and discipline. That’s the truth.

Making It Stick: Culture and Discipline

Here’s where most pubs fail. They do a stock count once, find a problem, implement a new process, and then stop doing it after three weeks because it feels like extra work. The variance creeps back. The over-pouring resumes. Nothing changes.

The reason most pubs that move from a messy spreadsheet to a disciplined weekly count claw back 1–2 GP points within a couple of months is not because the process is magic. It’s because consistency forces awareness. Your barkeeper knows you’re weighing the bottle. They pour tighter. A customer sees you taking stock seriously and stops asking for “a generous measure.” The till gets reconciled properly instead of being fudged.

Make the weekly line check a ritual, not a chore. Do it the same day, the same time. Print the variance report and stick it in the staff room. Don’t shame anyone for a bad week; celebrate a clean week. If the gin is running hot, bring the team together and ask why. Often the answer is useful—a new barkeeper is pouring loose, or a particular cocktail uses 1.5 measures and nobody logged it.

The conversation changes when the data is real. A manager saying “I think you’re over-pouring” gets nowhere. A manager saying “The gin lost 150g more than the till suggests—here’s the data—what do we do?” gets action.

This is not about suspicion. It’s about precision. And precision is what separates a pub that knows its numbers from a pub that hopes its numbers are okay.