Tenthing bar inventory method explained

Last updated: 26 June 2026

Most pub licensees don’t know they’re haemorrhaging money on draught lines every single week. A 1% stock loss on wet sales quietly costs a typical pub £3,000–£5,000 a year, and the worst part is you won’t see it coming if you’re just eyeballing your kegs. The tenthing bar inventory method is one of the oldest ways to spot that loss before it becomes a real problem, but it’s been quietly forgotten in favour of spreadsheets and guesswork. If you’re running a pub and you’ve never heard of tenthing, or you’ve heard of it but dismissed it as old-fashioned, you’re probably losing money right now. This article explains exactly how the tenthing method works, when to use it, and why it catches losses that most pubs never even notice until the damage is done.

What is the tenthing bar inventory method?

The tenthing method is a quick weekly check on your draught lines that tells you whether the amount of beer in the cask matches what you’ve sold through the till. It’s called “tenthing” because you’re dividing the cask into ten equal parts mentally (or physically, depending on how you set it up), and marking where the level sits on each cask at the start and end of the week.

The idea is brutally simple: if your till says you sold 40 pints of ale on Tuesday, and the cask level has only dropped 35 pints worth of space, something is wrong. That 5-pint gap is either waste, over-pouring, line cleaning loss, or a till error. Most of the time it’s a combination of all four, and it compounds week after week until it’s a real problem.

The method got its name because traditional pubs used to mark ten horizontal lines on the side of a cask with chalk or a marker, creating ten equal segments. You’d note where the beer level was on Monday morning, and where it was on Friday evening, then cross-reference that against sales volume. Modern pubs use the same principle but with a StockTap pub stock app or a simple spreadsheet with a measuring scale.

It’s not a full stocktake. It’s a weekly health check designed to catch small losses before they become big problems.

How the tenthing method actually works

Here’s the operational reality: you need three pieces of information to run a tenthing check.

First, you need to know how much beer you sold. That comes straight from your EPOS. Pull your draught sales by line for the week. A good EPOS will give you pints sold per line per shift.

Second, you need to know how much space one pint takes up in your cask. This varies by cask size and shape, but a standard 36-pint cask has roughly 1 inch of depth per 3.6 pints. A 50-litre cask (common in the UK) has roughly 2 inches of depth per 5 litres. You need to measure your own cask and create a simple conversion table. I did mine with a dipstick and a marker pen in about ten minutes.

Third, you need to physically measure where the cask level is at the start and end of the period. Use a simple wooden or plastic dipstick. Drop it straight down into the cask until it hits bottom, mark where the surface of the beer hits, and measure the depth. Write it down or log it in your system.

Then the maths: if your cask dropped 45 pints worth of depth, but your till only shows 40 pints sold, you’ve got a 5-pint variance. That’s your loss figure for the week.

In my own pub, I was running stock on a tangle of spreadsheets and still losing track of partial kegs and spirit measures. I built a simple count routine around a dipstick and a set of scales, and the weekly variance went from guesswork to a number I could trust within a fortnight. Now I run it every Monday morning before service, takes about 20 minutes for my six draught lines, and I know by 11 am whether the previous week was clean or whether there’s a problem to investigate.

Why tenthing matters more than a full stocktake

Most pubs run a full stocktake once a month or once a quarter. That’s a useful number for your accounts, but it’s too late if you want to actually stop losses as they happen.

A full stocktake tells you: “In March, you lost £400 on stock.” By then the damage is done. A weekly tenthing check tells you: “Last Tuesday something went wrong on the bitter line.” That’s actionable.

The number that actually matters is wet gross profit by line, not a single headline stock figure. If your cask variance for the week is consistently 5–8%, you’ve got a cellar or line issue. If it’s 2–3%, that’s normal breakage and expected waste. If it’s zero or negative, someone’s making a mistake on the measurement or the till isn’t ringing through properly.

Weekly tenthing also catches seasonal and operational patterns that a monthly stocktake completely misses. A busy Saturday might see heavy over-pouring. A heatwave might push your cellar temperature up and cause more line waste. A new staff member might not know how to clean the lines properly. A tenthing check every week will show you all of that within days, not weeks.

SmartPubTools customers who switch from a messy count routine to a disciplined weekly tenthing check typically claw back 1–2 GP points within a couple of months. That’s real money for a pub turning 25–30% wet GP.

Where draught losses hide

Understanding where the loss is coming from is half the battle. Tenthing catches it, but you need to know what to do about it.

Cellar temperature drift

If your cellar is warmer than it should be (anything above 13°C for cask ale), the beer expands slightly and more of it comes out of the tap as foam or waste. You might not see a dramatic change, but over a week it adds up. A tenthing check that shows a consistent 4–5% variance usually means a temperature problem, not a theft problem.

Line cleaning and purging

Every time you clean your draught lines (which should be weekly if you care about your margins), you’re running a pint or two of beer down the drain to flush out the old product. If your line cleaning is sloppy or your lines are longer than they should be (anything over 40 feet is too long), that waste doubles. A new pump or line replacement usually pays for itself within months.

Over-pouring and free pours

This is the killer loss that nobody wants to admit. A hand-poured 25ml spirit measure is often 32–35ml in real life. A “generous pint” is usually 28–32oz instead of 20. A tenthing check won’t catch this directly (you’d need till reconciliation for that), but a rising variance on your draught lines combined with flat or falling sales is a sign your staff are pouring heavy. It’s not always malice. It’s often just bad habit or kindness to regulars. You still need to address it.

Forgotten wastage

Dropped glasses, spoilt kegs, beer left sitting out at the end of service, partial kegs that got tipped down the sink. Most pubs have no record of this. It just vanishes from the till count into thin air. A proper tenthing check forces you to account for it, and you can then decide whether to write it off or investigate further.

How to run a tenthing check in your pub

What you need

• A simple wooden or plastic dipstick (or a ruler that won’t absorb moisture)
• A notebook or a spreadsheet with columns for: line name, day, cask opening level, cask closing level, till pints sold, calculated loss
• Your EPOS reports for the period you’re checking
• A conversion table showing how much depth equals how many pints for each cask size you use

The weekly routine

Step 1: Pick a fixed day and time. Monday morning before service is ideal because you’ve got fresh data from the whole previous week. It takes 10–15 minutes per draught line.

Step 2: For each cask in use, drop your dipstick to the bottom and mark where the beer surface hits. Write down the measurement. Do this before anyone starts pouring for the day.

Step 3: Pull your EPOS report for the previous week and extract pints sold by draught line. Most systems will give you this broken down by shift or by day.

Step 4: Calculate what the cask level should be. If you sold 140 pints of bitter last week, and one pint of depth equals 1.1 inches of drop (use your own ratio), the cask should have dropped 1.54 inches. Measure what it actually dropped. The difference is your variance.

Step 5: Log the variance and watch for patterns. One-off variances of 2–5% are normal. Consistent variances above 5% every week mean you have a recurring problem. Zero variance means either everything is perfect (unlikely) or someone isn’t measuring correctly.

What to do if you find a loss

Don’t panic. First, check your numbers are right. A measurement error is the most common culprit. Second, check whether you’ve logged any wastage (spoilt cask, line cleaning, dropped glasses) that accounts for it. Third, if it’s on a draught line, check your cellar temperature and line length. If it’s consistent week on week, call an engineer to look at the pump and lines. If the variance is only on certain shifts, you’ve probably found a staff training issue.

Tenthing vs. other inventory methods

Tenthing vs. full monthly stocktake

A full stocktake gives you a precise picture once a month, but by then losses are already baked in. Tenthing gives you early warning. Use both: tenthing weekly to catch problems, full stocktake monthly to reconcile against your accounts.

Tenthing vs. spreadsheet-only tracking

Most pubs use a spreadsheet and hope for the best. The problem is that spreadsheets are passive. You input data and file it away, but you never really look at it until the month is over. Tenthing forces you to physically check the cask every week, which makes you notice things: a pump that’s running slowly, a line that’s always producing excessive foam, a cask that never seems to match the till. A spreadsheet is a record. Tenthing is an action.

Tenthing vs. an app or POS integration

A system like StockTap pub stock app automates the logging and the variance calculation, which saves time and removes arithmetic errors. But the method underneath is still tenthing. You still physically measure the cask and record the result. The app just makes it quicker and gives you better reporting so you can spot patterns and trends faster.

The advantage of using an app is that you get weekly variance trends, historical comparison, and alerts when a line goes out of spec. A spreadsheet gives you the same data, but you have to manually create the charts and spot the patterns yourself. For most pub operators, time is the limiting factor, not cost.