Calculate cask ale wastage percentage

Last updated: 29 June 2026

Most pub licensees have no idea what their actual cask ale wastage percentage is—they just know their stock doesn’t add up. The frustrating truth is that a 1% stock loss on wet sales quietly costs a typical pub between £3,000 and £5,000 every single year, yet most pubs never measure it properly. You’re probably running partial kegs you’ve forgotten about, losing product to slow pours, bad cellar temperature, or poor line cleaning waste, and blaming it on theft when it’s actually measurement error and untracked wastage. The good news is that calculating your real wastage percentage is straightforward—if you have a dipstick, a set of scales, and fifteen minutes a week. This article will show you exactly how to do it, and what the number actually tells you about your cellar operation.

What cask ale wastage percentage actually means

Your cask ale wastage percentage is the difference between the stock you should have (based on your till and delivery records) and the stock you actually have (based on your physical count). The most effective way to understand your cask ale wastage percentage is to measure it as the gap between what your till says sold and what your cellar physically shows you have left.

This is not just about beer spilled during line cleaning or a pint left in the glass. Real wastage in a pub cellar includes:

• Product left in lines after a line clean (the biggest hidden loss in most pubs)
• Slow pours and over-pouring (a free-poured 25ml is often 32–35ml in reality)
• Beer lost to poor cellar temperature or carbonation drop
• Partial kegs you forgot about that didn’t get fully used
• Measures poured but not rung through the till
• Spillage, samples, staff drinks, and actual theft

The reason most pubs can’t calculate this accurately is that they don’t have a baseline to measure against. You need a starting point: your opening stock value. Once you have that, you can track every delivery, every till sale, and every physical recount. The difference between what you mathematically should have and what you physically do have is your wastage.

The formula for calculating wastage percentage

Cask ale wastage percentage = ((theoretical stock in litres – actual stock in litres) ÷ theoretical stock in litres) × 100.

Here’s what each part means:

• Theoretical stock = opening stock plus all deliveries minus all till sales (in litres)
• Actual stock = what you physically count in your cellar (in litres)
• The result = your wastage percentage for that period

Example:

Let’s say you opened Monday morning with 100 litres of cask ale. You took a 50-litre delivery on Wednesday. Your till rang through 130 litres of sales over the week. On Friday, you dip every cask and partial keg and measure 18 litres remaining.

• Theoretical stock = 100 + 50 – 130 = 20 litres
• Actual stock = 18 litres
• Wastage = ((20 – 18) ÷ 20) × 100 = 10%

That 2-litre difference is your wastage—10% of what you should have had. In a real pub with a busier cellar, you’d spot this at once and know something’s wrong with your line cleaning or temperature control.

The key is that you must count the same way every time. StockTap pub stock app automates this calculation for you once you’ve entered the numbers, but the measurement itself has to be done manually in the cellar.

How to measure and record your data

Forget spreadsheets that lose rows or where you forget whether a keg was already half-empty. Here’s what a working routine looks like:

Weekly count process

• Same day, same time each week — I count on Thursday morning before service. Consistency matters because if you count Monday one week and Friday the next, you’re measuring different stock volumes and the variance becomes useless.
• Dip every cask and partial keg — use a simple dipstick (under £5). Measure depth in centimetres and convert to litres using your keg size chart. A standard 36-pint cask needs a different conversion than a 50-litre keg.
• Weigh open spirit bottles — grab a digital scales (£15 from any catering supplier). Record the weight, then weigh the full bottle on your next spirit delivery and the difference is what was sold versus what you thought went out.
• Record deliveries the day they arrive — don’t wait until Thursday. Write down quantity and product code on a simple sheet, or snap a photo of the docket.
• Reconcile against till data the same day — pull your EPOS report for the same period and match it against your count. The gap is your wastage.

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. Once you can trust the number, you can act on it.

What to record

You need four pieces of information each week:

• Date of count and opening stock (litres)
• Deliveries received (litres and product name)
• Till sales (litres, pulled from EPOS)
• Closing stock (litres, physically dipped and weighed)

That’s it. From those four numbers, you calculate wastage. SmartPubTools has templates for this, but a notebook and a calculator will work just as well if you do it consistently.

Why your numbers don’t match the brewery’s

The brewery does a stocktake when they visit—usually every 4 weeks, sometimes less often. They measure what’s physically there and cross-reference it against delivery dockets and till data. But here’s the catch: they’re checking total stock, not your wastage percentage. Their job is to confirm you’re not running a massive shortfall; your job is to spot the small leaks that add up to thousands of pounds a year.

Your number will almost never match theirs exactly, and that’s fine. The number that actually matters is your weekly or fortnightly variance, not a single headline stock figure. If you’re within 2–3% every single week, you’re sound. If you suddenly jump to 8% one week, you know something changed—a new cellar person, a new line cleaning routine, a temperature spike.

The brewery’s four-weekly visit is a checkpoint, not your management tool. Your weekly dip and weigh is the early warning system. Most pubs that move from a messy spreadsheet to a disciplined count claw back 1–2 GP points within a couple of months, simply because they start spotting and fixing the leaks before the brewery visit even arrives.

Common mistakes that hide real losses

Forgetting partial kegs

You ran out of Doom Bar on Saturday night, grabbed a new keg, and put the half-empty one behind the stillage. Three weeks later, it’s still there and you’ve written it off mentally. Meanwhile, your count sheet assumes it’s gone. That’s a 20-litre loss that never actually happened—it’s just a data error.

Fix: Mark every partial keg with a sticker and a date. Dip it every week even if it looks empty. Get it out of the cellar once you’ve verified it’s genuinely flat.

Not accounting for line loss

A standard cask ale line (10 metres, 3/16-inch diameter) holds about 1.5 litres. When you clean the lines, all that beer comes out. If you clean lines twice a week, that’s 3 litres of product gone to waste every week, or 156 litres a year. Most pubs just accept it as part of the game and never measure it.

Fix: Calculate your line volume once, then subtract it from your weekly count as a known loss (not mystery wastage). Then measure everything else against what’s left. This turns a hidden leak into a visible, manageable cost.

Mixing till data with cash sales

If your EPOS only records card and contactless payments, and you’re taking 30% cash, your till data is missing a third of your sales. That means your theoretical stock calculation is fundamentally wrong. Your wastage percentage will always be sky-high because you’re comparing actual product against incomplete sales data.

Fix: If you’re still running a hand-written cash till alongside your EPOS, add those numbers manually to your sales total. Or, better, move all cash through the till. Most modern EPOS systems can handle cash just as easily as cards.

Over-pouring and not measuring it

Spirits hide losses in over-pouring. A free-poured 25ml measure is often 32–35ml in reality. If you pour 20 pints of bitter a day at 5ml more per pint than you’re charging, that’s 100ml a day you’re not ringing through. Over a year, that’s 36 litres you’ve given away for free.

Fix: Weigh your spirit bottles weekly. A 70cl bottle of 40% ABV spirit weighs roughly 700ml before opening. Record the weight when you open it, then weigh it every Thursday. The difference between what you weighed and what your till says you sold tells you whether you’re over-pouring.

What a healthy wastage percentage looks like

For cask ale, a well-run pub should sit between 2–3% wastage. This accounts for line cleaning, spillage, and minor temperature loss. If you’re at 5% or above, you have a real problem—either your lines are filthy and need aggressive cleaning (losing more beer than they should), your cellar temperature is drifting, you’re measuring wrong, or there’s genuine theft happening.

Here’s what the ranges mean in real terms:

• 1–2%: Excellent. You’re tight on controls and your cellar person knows what they’re doing.
• 2–4%: Normal. This is the range most decent pubs sit in. You have minor losses but nothing systemic.
• 4–6%: Warning sign. Something’s slipped. Check your line cleaning routine, cellar temperature, and whether you’re measuring accurately.
• Above 6%: Crisis. You need to stop, audit everything, and get the brewery involved.

Remember: this percentage varies by product type. Cask ale is usually tighter than draught lager (which loses more to temperature and carbonation), and spirits vary wildly depending on whether you free-pour or use optics.