How many pints in a half keg?

Last updated: 29 June 2026

Most pubs lose money on draught beer without ever realising it, and the confusion starts with the numbers themselves. A half keg—the one sitting in your cellar right now—contains exactly 40 pints. But knowing that number and actually counting what’s left are two very different things, and that gap is where money walks out the door. You can’t manage what you don’t measure, and I’ve watched licensees spend years guessing at their stock instead of knowing it.

This matters because a 1% stock loss on wet sales quietly costs a typical pub £3,000–£5,000 a year. That’s not theft. That’s measurement error, poor cellar temperature, bad line cleaning, and the quiet drain of over-pouring on the till. A proper weekly line check—and I mean actually dipping every cask and partial keg—catches it before it becomes a habit.

In this guide, I’ll show you the real number in a half keg, how to measure what’s left, and why your spreadsheet isn’t catching what’s actually going missing.

How Many Pints in a Half Keg

A half keg holds 40 pints of finished product. This is the standard measure across UK pubs, whether you’re running a Marston’s tied house, a free trade, or anything in between. A full keg is 80 pints, a quarter keg is 20 pints. The half keg is what most independent pubs and many chains run as their primary draught measure.

But here’s what most licensees don’t realise: that 40-pint figure is the number in a full half keg. The moment you crack it open and start pouring, you need to know what’s actually left, and that’s where most pubs fail. You can’t just look at the keg and guess. You can’t trust what the brewery’s delivery note says went out. You can’t rely on last week’s count. You need a number from today, in your cellar, taken the same way every time.

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. That’s when I actually saw where the leaks were.

How to Measure Stock Left in a Partial Keg

The only reliable way to count what’s left in a half keg is a hand dipstick. Here’s the process:

• Get a dipstick. This is a simple graduated ruler, usually plastic, marked in centimetres. Any brewery supplier will have them. Cost is minimal. No excuses.
• Place the keg on a level surface. Sloped cellar floors will throw your reading off. Use a spirit level if you need to.
• Insert the dipstick vertically from the top of the keg until it touches the bottom. Mark or note where the liquid surface is.
• Measure the depth to the liquid surface. Every keg has a standard conversion chart printed on it or available from your supplier. Depth in centimetres converts directly to litres remaining, which converts to pints (divide litres by 0.568 to get pints, or use a ready-made chart).
• Write the number down immediately. Don’t rely on memory. Date it, line name it, note the time if you’re being thorough.

That’s it. Five minutes per keg. A standard pub with four draught lines on rotation takes twenty minutes a week. This is not optional if you want to know your numbers.

Why this matters: a visual guess or a scale weight alone won’t work reliably because you can’t judge how much beer is left by looking at the keg from the outside, and a scale tells you weight but not pints consumed. A dipstick reading converts directly to pints, which is the only currency that matters on your till.

Why Your Count Matters More Than the Brewery’s

The brewery stocktaker comes once a quarter, maybe once a month if you’re lucky. They count what they deliver, and then you’re responsible for everything that happens in your cellar. By the time they show up again, three months of losses, errors, and unmeasured wastage has compounded.

Your count—done weekly, in your cellar, reconciled against your till on the same day—is the only one that actually tells you whether you’re making money on that line. The number that actually matters is wet GP by line, not a single headline stock figure. Spirits hide losses in over-pouring (a free-poured 25ml is often 32–35ml in a busy service), draught hides it in poor cellar temperature and bad line cleaning waste, and most stock ‘theft’ is actually measurement error and forgotten wastage.

When I started reconciling my weekly dip count against what the till said sold on each line—same day, no time lag—I found variance I’d never seen before. Variance is information. It tells you where the problem is. And it’s only visible if you’re counting yourself, consistently, every week.

Common Mistakes That Hide Draught Losses

Here are the mistakes I see most often, and what they cost you:

Counting inconsistently or too infrequently

If you count one week and skip the next, you can’t tell whether a variance happened in week one or week two. If you sometimes use a scale and sometimes a dipstick, your numbers won’t compare. You lose the thread. Count the same line, the same way, on the same day every week. That’s the only way to spot a trend.

Ignoring cellar temperature

Beer expands and contracts with temperature. A cellar that drifts from 13°C to 16°C will show higher pints consumed on the till than actually poured. The beer itself is losing CO₂, head retention drops, and you pour a bigger measure to compensate. Your variance will spike, and you’ll blame theft or pour control when the problem is the thermostat. Check your cellar temperature log weekly. Keep it between 12–14°C.

Not cleaning lines properly

Old beer left in the lines after a pull-through doesn’t show on your till. It shows as a gap between what the dip says and what you sold. Line cleaning waste is real, it’s invisible, and it can be 2–3 pints a week if your lines are running more than 3 metres. Know your line length. Know how much you’re flushing. Account for it.

Reconciling with a time lag

If you dip the keg on Tuesday but check the till on Friday, you’ve lost the thread. Changes in stock, voids on the till, staff changes—they all blur together. Dip and reconcile on the same day, ideally the same hour. Same-day variance is actionable. Three-day-old variance is guesswork.

Measuring in units that don’t match your till

Your till records pints sold. Your spreadsheet needs to track pints remaining and pints consumed. If you’re counting in litres, converting badly, or mixing measures, your variance will be meaningless. Convert once, carefully, using a standard chart. Stick to pints.

Weigh open spirit bottles, dip every cask and partial keg, and reconcile against till data the same day. That’s the real method. It sounds tedious. It is. But it’s the only way to know whether you’re making money.

Building a Weekly Count Routine

This is where most pubs fail. They know what to do but don’t have a system, so it doesn’t happen. Here’s what actually works:

Pick a day and time

Tuesday morning, 10am. Before service. Same time every week. Make it a habit, not a decision. You won’t do it if it’s optional.

Get the right kit

A dipstick for kegs, a set of digital scales for spirits, a pen, a notebook or spreadsheet, and your till reconciliation report for that day. Nothing fancy. Nothing expensive.

Document everything

Date, line name, keg number (if you rotate), depth reading, pints remaining, pints sold (from till), variance, and any notes (line flushed, temperature drift, cask change, etc.). The notes are where you spot patterns.

Reconcile immediately

While you’re still in the cellar or immediately after. Pints remaining today minus pints remaining last week equals pints consumed. Compare to pints sold on the till. The gap is your variance. If it’s under 2%, you’re doing well. Over 3%, investigate.

Review monthly

Take your four weekly counts for each line. Plot them. Look for trends. One bad week is noise. Three rising weeks is a problem. That’s when you adjust temperature, change your line, or check pour control.

This system takes about 30 minutes a week for a four-line pub. Most licensees waste more than that on admin that doesn’t actually tell them whether they’re making money. A proper weekly line check catches stock loss before it becomes a habit. Most pubs that move from a messy spreadsheet to a disciplined count claw back 1–2 GP points within a couple of months. At typical turnover, that’s £4,000–£8,000 a year sitting on the table waiting to be counted.

Making the Numbers Actionable

Knowing you have a 4% variance on your best-selling bitter is one thing. Knowing what to do about it is another. Here’s the framework:

Variance under 2% on all lines

You’re in control. Keep doing what you’re doing. Document it for the brewery. Use it as proof your cellar is being managed properly.

Variance 2–3% on a single line

Check your cellar temperature. Check your last line clean date. Check whether that line has been changed recently and the old stock is still draining. One week of variance is noise. Two weeks is a signal. Three weeks is a problem.

Variance above 3% on any line

Something is wrong. Options: (1) Temperature is drifting—check the thermometer. (2) Line is dirty—pull it through and clean it. (3) Keg is faulty—swap it immediately and keep the old one separate. (4) Till is recording differently—check your point-of-sale setup and staff pour discipline. (5) You’re measuring wrong—re-check your dipstick reading and conversion maths. Don’t guess. Test each one.

Track variance as a percentage, month on month. Most pubs run 2–5% variance when they’re not managing it. A properly run cellar runs 0.5–1.5%. The difference is not a sign of genius—it’s just consistency. Same method, same day, every week, reconciled immediately.

When you have reliable numbers, you can see which lines are actually profitable, which are hiding losses, and where your real GP is coming from. Most pubs don’t know their wet GP by line. They know their headline beer margin, but they don’t know whether their best-selling lager is more profitable than their cask ale when you account for wastage, temperature loss, and line cleaning. The keg count is the foundation of that visibility.

If you’re running your stock count on a spreadsheet, you’re not wrong—but you’re also not capturing the context. You need to see your count, your till, your cellar temperature, and your staff shifts all in one place, reconciled automatically, so you can spot when something changed. StockTap pub stock app does this by design. It’s built by a working pub landlord who got tired of switching between five different screens to answer a simple question: did we make money on this line this week? The system logs your keg readings, reconciles them against your till on the same day, flags variances above your threshold, and stores the history so you can spot trends. It’s not fancy. It’s not a subscription. It’s just the count routine you should be doing anyway, with the paperwork done automatically.

For more information, visit SmartPubTools.