What cask ale ullage is and why it matters

Last updated: 29 June 2026

Most pub operators confuse ullage with profit, and that confusion costs them thousands a year. Ullage is not the space at the top of a cask—it’s the total amount of beer missing from a full cask, whether sold, wasted, or genuinely lost. The difference between understanding this and ignoring it can be £3,000 to £5,000 a year in unaccounted-for loss on wet sales alone. This guide explains what cask ale ullage actually is, how to measure it properly, and why most pubs never see the real number that matters: wet gross profit by line, not a headline stock figure.

What is ullage in a cask?

Ullage is the volume of beer missing from a cask at any point in its life—sold to customers, poured down the sink during line cleans, lost to leaks, or unaccounted for. The word comes from old French and literally means “the amount by which a container falls short of being full.” In a pub cellar, it’s the gap between what you bought and what’s actually in the barrel right now.

Most landlords think of ullage as just the headspace at the top of a cask. That’s wrong. A full cask sits with a tiny air gap at the very top. Once you start selling from it, the gap gets bigger. At the end of the cask’s life, when you’ve sold 80 litres and there’s 12 litres left with a 8-litre headspace, you have a total ullage of 20 litres—the 8 litres of headspace plus the 12 litres still in the barrel that haven’t been sold yet. Neither of those 20 litres is making you money.

This is why weekly dipping matters. You’re not tracking headspace. You’re tracking the total volume of unsold beer in every cask, so you know exactly how much is moving and how much is stuck.

The three types of ullage every pub should track

Sold ullage

This is the beer that actually left your pub through the tap as a paid pint. It’s the good kind. It’s revenue. A full cask is 36 litres. If you sell 28 litres and the cask is empty except for 8 litres of sediment and headspace, you’ve achieved 28 litres of sold ullage—that’s what you want.

Waste ullage

This is beer that left your pub but didn’t generate revenue. Line cleaning waste. A bad pour that went down the sink. A cask that was breached and lost three litres. A customer who sent a pint back. A staff member’s training pour. A sample for the brewery rep. Every pub loses 8–12% of draught volume to waste ullage before it ever reaches the till, and most operators have no idea where it goes. This is the single biggest controllable loss in draught beer.

Dead ullage

This is the remaining beer in a cask at the end of its saleable life. When a cask runs dry but still has 2–4 litres sitting on top of the sediment that’s impossible to pull through the tap, that’s dead ullage. It’s also normal. Every single cask has it. The mistake is thinking it’s theft or wastage—it’s neither. It’s inevitable physics.

What matters is tracking all three so you can spot the pattern. If your sold ullage is consistently 24 litres per cask when it should be 28, you have a problem. If your waste ullage is 4 litres when it should be 2, you have a line cleaning or training problem. If your dead ullage keeps creeping up to 5 litres, your cellar temperature is too warm or your cask handling is rough.

How to measure cask ullage properly

You need three pieces of kit: a dipstick, a notebook, and till data from the same day.

The dipstick method

A dipstick is a simple wooden or plastic rod marked in litres. You insert it into the shive hole at the top of the cask until it touches the bottom, pull it out, and read the level. Most brewery reps will give you one free. If yours won’t, buy one for £8–12. It takes 30 seconds per cask.

The process:

• Every Tuesday morning (or whatever your weekly stock day is), dip every active cask before service starts
• Record the litre reading next to the cask ID (e.g. “Guinness 001 = 18L”)
• Do the same for every partial keg or spirit bottle—weigh the bottle on a set of kitchen scales if it’s spirits, measure the keg if it’s lager
• Pull till data for the same 24-hour period (Monday 6am to Tuesday 6am is easiest)
• Reconcile on the same day: the difference between last week’s dip and this week’s dip should roughly match the till sales for that line, plus or minus expected waste

This is not a five-minute job. A pub with eight draught lines and six spirit bottles takes about 20 minutes. But it’s the only job that stops you losing £3,000–£5,000 a year. I was running stock on a tangle of spreadsheets and still losing track of partial kegs and spirit measures. Once I built a simple count routine around a dipstick and a set of scales, the weekly variance went from guesswork to a number I could trust within a fortnight.

Why spreadsheets fail

A spreadsheet can record your dip readings. But a spreadsheet can’t tell you why a cask of Timothy Taylor is showing a 2-litre shortfall. It can’t flag that your line cleaning waste jumped from 1.2 litres to 2.8 litres. It can’t compare your Guinness draught profit to your lager draught profit in real time. That’s why the StockTap pub stock app exists—to do the reconciliation and variance spotting automatically so you see the actual problem, not just the number.

Why your spreadsheet isn’t catching your losses

The reason most pub stocktake spreadsheets miss ullage problems is simple: they only record the final number. A cask shows 16 litres. Last week it showed 24 litres. The difference is 8 litres. Your spreadsheet says “8 litres sold—great.” But what if the till only rang 6 litres? Where’s the other 2 litres?

Your spreadsheet doesn’t know. It doesn’t care. It just stored two numbers and subtracted them.

The number that actually matters is wet gross profit by line, not a single headline stock figure. Spirits hide losses in over-pouring—a free-poured 25ml is often 32–35ml. Draught hides it in poor cellar temperature and bad line cleaning waste. Most stock “theft” is actually measurement error and forgotten wastage. The only way to see it is to weigh open spirit bottles, dip every cask and partial keg, and reconcile against till data the same day.

Your spreadsheet can do this. But it requires you to build the logic in every single row, for every single line, every single week. That’s where most operators fall behind. They record the numbers, they forget to reconcile, or they reconcile once and then stop. And by the time they realise there’s a problem, they’re already six months behind.

This is why most pubs that move from a messy spreadsheet to a disciplined count routine claw back 1–2 gross profit points within a couple of months. It’s not magic. It’s just actually noticing the variance instead of ignoring it.

The real cost of ignoring ullage

A typical three-barrel pub with four draught lines loses about 2–3 litres a week to unmeasured waste and unspotted shortfall. That’s roughly 100–150 litres a year. At an average draught margin of £1.80 per litre, that’s £1,800 to £2,700 a year. Add spirits over-pouring (even a conservative 10% on spirit sales across four optics), and you’re easily over £3,000. Add the cost of stock that never gets rung in because the till operator forgot to log a void, or a delivery that was received but not counted, and you’re at £4,000–£5,000.

For a tenanted or leased pub running on a margin of 50–55%, that lost £3,000–£5,000 represents real money you never see. It’s the difference between a pub that covers its overheads and one that doesn’t.

The worse part: most of this loss isn’t theft. It’s not a staff member pulling pints into their own pocket. It’s:

• Over-pouring during training or slow service
• Line cleaning waste that nobody tracked
• Casks left sitting at room temperature for three days before being tapped
• A delivery that was counted wrong when it came in
• A till void that was never logged
• Spillage during a cellar change that was binned without recording

None of that is fraud. All of it is money out the door. And none of it shows up if you’re not measuring ullage properly.

How to stop the bleed

Step 1: Establish a weekly dip routine

Pick one day a week. Tuesday morning before service is ideal because it’s far enough from the weekend that you’re not catching someone else’s mess, and you have time to act on what you find. Dip every cask. Weigh every open spirit bottle. Record it in the same place every week so you can see a trend.

Step 2: Reconcile the same day

Don’t wait until Friday. Pull till data for the 24 hours up to your dip time, subtract this week’s dip from last week’s dip, and compare it to the till. If a cask of Guinness should have sold 8 litres based on till data and the dip shows 8 litres missing, you’re clean. If the till says 8 litres but the dip says 10 litres missing, you have a 2-litre variance. That’s your flag.

Step 3: Investigate variances above 10%

A 1–2 litre variance on a 30-litre cask is normal measurement error. A 5-litre variance is a problem. It could be:

• A leak nobody noticed
• A line clean that was logged in the wrong week
• A till error (void not logged, ring-in error, or till crash)
• A cask that was tapped and breached during service
• Over-pouring on a busy shift

Ask questions. Don’t assume. Most of the time, the operator knows what happened—they just didn’t write it down.

Step 4: Track waste ullage separately

Create a simple log: every line clean, every training pour, every void, every breach. Record it at the time, not at the end of the week. This is where SmartPubTools saves time—it logs each event and totals them weekly so you’re not manually adding up 50 line cleans.

Step 5: Train your staff

Your team needs to understand that over-pouring is loss. A 25ml spirit poured as 32ml is a 28% giveaway. Over one month, that’s dozens of pounds. Make it a counting exercise, not a lecture. Show them: “We poured 120 spirits this week. If each one went 7ml over, that’s 840ml we didn’t charge for. At £28 per bottle, that’s £24 in loss before you even see the cask numbers.”

People change behaviour when they see the number.

---