Keg checker vs scales: which method wins

Last updated: 29 June 2026

Most pub licensees think they have a stock problem when what they actually have is a measurement problem. A 1% stock loss on wet sales quietly costs a typical pub £3,000–£5,000 a year, and the keg checker versus scales debate misses the real point: you need both, and you need to use them the same day every week, not when you feel like it.

If you’re running your stocktake on gut feel or a spreadsheet that hasn’t been updated since Tuesday, you’re already losing money. The question isn’t whether keg checkers or scales are more accurate in isolation — it’s which combination catches losses fastest and which one you’ll actually use when you’re busy.

After 15 years running a Marston’s pub and moving from a tangle of spreadsheets to a disciplined weekly count using a dipstick and a set of scales, the variance in my stock records went from guesswork to a number I could trust within a fortnight. That number matters because it’s the only early warning you get before a small leak becomes a big problem.

In this article, you’ll learn exactly how each method works, where each one fails, and why the answer isn’t “one or the other” but “both and a proper routine.”

How keg checkers work and what they actually measure

A keg checker — also called a dip or dipstick — is a simple brass or stainless steel rod marked with measurements. You drop it into a cask or keg, it floats, and the mark on the liquid surface tells you the depth of product left. From that depth, a conversion table (usually printed on the stick itself or a chart) tells you how many litres or pints remain.

The keg checker assumes the cask is perfectly level, the product density is consistent, and nothing else is happening inside the container. In a real pub cellar, none of those assumptions hold.

A slightly tilted cask on a sloped cellar floor will give you a false reading — sometimes wildly false. A keg that’s been sitting for a week at cellar temperature will have lost liquid to evaporation (most noticeable with ales and ciders). A partial keg with a slow leak at the tap will show full on the dipstick because the liquid level hasn’t dropped yet — the beer is literally draining out of the bottom of the keg while the contents look stable.

Where keg checkers excel is speed and simplicity. You can dip a 50-barrel in under 10 seconds. It costs £8–£15. It requires no batteries, calibration, or knowledge. Any staff member can do it.

The major brewery stocktakers (the ones who show up once a month to reconcile the account) use keg checkers because they’re fast and they work across hundreds of pubs. That doesn’t mean they’re the most accurate — it means they’re the most practical for that scale of work.

How scales work for spirit stock and partial kegs

A scale — specifically, a set of electronic scales accurate to 0.1 kg or better — measures the total weight of a container and its contents. You weigh an empty bottle, weigh it again when it’s full (or partially full), and the difference tells you exactly how much liquid is in it.

For spirits, this is the only method that catches over-pouring. A free-poured 25ml is often 32–35ml in practice. A scale will show that immediately. A keg checker can’t measure what’s inside a bottle at all.

For partial kegs and casks, scales catch what keg checkers miss: slow leaks, evaporation, and condensation changes that affect the surface level but not the actual product weight.

Scales measure what actually went out of the container, not what the surface level says. That’s why they catch losses that nothing else does.

The downside: scales are slower (30–60 seconds per spirit bottle, 40–90 seconds per kegged line with setup time), they cost £80–£250 for a decent set, they need batteries or power, they need to be level and recalibrated regularly, and most pub staff find the routine tedious after the first week.

Accuracy head-to-head: real-world conditions

On paper, in a laboratory, with perfect conditions: both methods are accurate to within 1–2% if used correctly.

In a real pub cellar at 52–55°F with natural temperature variation, uneven flooring, tired staff doing the count at 10 p.m. after a busy service, and kegs that have been in place for three weeks: neither method is reliable on its own.

Here’s what actually happens in the field:

• Keg checkers give false high readings when a cask is tilted, when condensation is sitting on top of the liquid, or when the cask has a slow leak below the tap. The dipstick shows plenty left; the till says you sold nothing; and two days later someone notices the line is flat.
• Scales catch leaks that checkers miss because they measure total weight, not surface level. But scales are useless for full kegs (they all weigh about the same when full, so variance is invisible until you’re three-quarters through the keg).
• Neither method alone catches over-pouring in spirits, because neither measures what actually left the bottle — they measure what’s left in it. A bottle that started at 1 kg, now weighs 0.7 kg, and the till says you sold 18 measures when you actually poured 24 tells you something. A keg checker can’t measure spirit pours at all.

In my own pub, I ran a six-week test comparing daily keg checker readings against weekly scale readings on the same kegs. The checker average was off by 3–7 litres per keg. The scales were off by 0.5–1 litre. But the scales alone couldn’t tell me which kegs were leaking versus which were just slow sellers — I needed both readings to see the pattern.

When each method fails and why

Keg checkers fail silently and consistently in these scenarios:

• Any cask or keg not on a perfectly level surface (most pub cellars aren’t perfectly level).
• Slow leaks below the tap or at the keg connector — the liquid is leaving, but the surface level hasn’t dropped yet.
• Temperature swings — a 5°C change can cause visible condensation changes that read as liquid level changes on a dipstick.
• Casks that have been standing for weeks — evaporation becomes visible on the dipstick reading but the till data says nothing sold.

Scales fail in different ways:

• Full kegs look the same weight whether they’re full of beer or half-empty — scales don’t work until you’ve actually used some of the contents.
• Condensation on the outside of bottles throws off the weight by 10–20 grams (usually small enough to ignore, but it compounds across a whole cellar).
• Electronic scales drift if not recalibrated weekly — a £150 scale is only as good as its last calibration.
• Staff resistance — scales are seen as slow and tedious, so they’re skipped or rushed, making the data worthless.

The number that actually matters is wet GP by line, not a single headline stock figure. Spirits hide losses in over-pouring, draught hides it in poor cellar temperature and bad line cleaning waste, and most stock ‘theft’ is actually measurement error and forgotten wastage. Weigh open spirit bottles, dip every cask and partial keg, and reconcile against till data the same day.

The combined approach that actually works

You use a keg checker on every cask and keg to establish the baseline and spot obvious problems. Then you use scales on every open spirit bottle, every partial keg (once it’s below the halfway mark), and any line that’s showing variance between the checker and the till.

The StockTap pub stock app is built around this exact workflow because it was designed by someone who actually ran a pub and got tired of spreadsheets that didn’t catch leaks.

A working routine looks like this:

• Every Monday morning (or your quiet day): Dip every cask, keg, and partial container. Record the reading.
• Same session, immediately after: Weigh all open spirit bottles. Record the weight against the previous week’s weight.
• Same day, before lunch: Pull the till data for that line. Compare what you recorded against what the till says sold. If there’s variance of more than 2–3%, dig into why.
• Weekly, in writing: Log the three numbers side by side: checker reading, scale reading, till data. The pattern tells you everything.

Why the same day? Because your memory is terrible. Wait until Wednesday and you’ll have forgotten why the bitter was low on Tuesday. Reconcile on the day and you can ask the bar staff, “Did we have a spillage?” or “Was the line off?” while it’s still fresh.

When scales beat keg checkers

In four specific situations, scales are non-negotiable:

1. Open spirit bottles. A keg checker can’t measure a bottle. Only scales catch the difference between a 25ml pour and a 35ml free-pour. This is where most pubs leak margin without knowing it.

2. Partial kegs below halfway. Once a keg is less than half full, the checker reading becomes increasingly unreliable because the margin of error grows. A scale will show you the exact weight loss since last week.

3. Casks with history of slow leaks. If a particular cask has leaked before, the keg checker can’t tell if it’s leaking this week. Scales will show weight loss even if the surface level looks OK.

4. Reconciling till variance. When the till says you sold 40 pints but the checker says you only lost 35, scales tell you which is right. (Usually the till is right and you’re pouring too heavy.)

How to build a routine you’ll actually stick to

The best stocktake routine is the one you actually do every week, not the one that’s theoretically perfect but gets skipped when you’re busy.

Start small. Don’t try to weigh every bottle and dip every keg and reconcile against the till in your first week. You’ll burn out.

Week 1–2: Dip every cask and keg. That’s it. Get the team used to a Monday morning dip routine. It takes 15 minutes for a 10-line pub.

Week 3–4: Add scales to the open spirits only. Don’t weigh sealed bottles. Just the ones actively being poured from. Another 10 minutes.

Week 5+: Once those two steps are automatic, add the till reconciliation. Pull the data, compare it, ask the obvious question (“Why is the bitter low?”), and log it.

The objection I hear most is: “I don’t have time to stocktake every week.” The truth is, you don’t have time not to. A 1% stock variance on a typical £800–£1,200 weekly wet sales figure is £8–£12 a week that’s just missing. That’s £400–£600 a year that’s gone. Run a proper routine for a couple of months and most pubs claw back 1–2 GP points. The math is brutal in your favour.

The second objection: “My spreadsheet works fine.” It doesn’t. Spreadsheets work until they don’t — until someone forgets to update a row, or copies a number from the wrong week, or the file gets saved in two places and you’re working from the wrong one. I ran my pub on spreadsheets for five years and never knew I was leaking money until I started keeping a dip log in a proper routine.

The real verdict: use a keg checker on all casks and kegs for speed and simplicity, use scales on spirits and partial kegs to catch what checkers miss, and reconcile against the till on the same day every week. That routine catches 95% of losses that most pubs never see because they’re not looking.

You’re already running a stocktake. The question is whether you’re running one that actually works or one that’s just keeping the paperwork tidy.

For more information, visit SmartPubTools.