Why Guinness Will Show Over 100% Yield on Your Stocktake Report

David Holden

Sep 1

7 min read

Updated: Sep 4

This is Part Two of a four-part series on reading your own stocktake report properly.

Catch up on Part One: Your Stocktake Report Is Either a Goldmine or a Shambles

A Guinness keg of 88 pints that returns 92 pints in sales isn't a mistake on your stock report. It's meant to happen. If it isn't, then you ought to be investigating why not.

Every keg over 100% yield gets the same reaction on social media: somebody's fiddling the numbers and the customers.

Take Guinness. I'd challenge anybody to pour a pint without a head being formed. The sixty-second settle is all part of the ritual, it's not bar staff adding froth on top. A branded glass that is fill to the brim is going always going to generate a minor gain.

The law never actually settled this. In 1985 the Weights and Measures Act said the gas in a beer's foam should be disregarded when measuring what you'd been served, which would have meant a full pint of liquid, head on top, free. That clause was quietly repealed in 1994, and nothing's replaced it since. So in 1993, with the law already shaky, the BBPA agreed its own guidance with what was then the Department of Trade and Industry, long since split into other departments: a pint served with a head has to be at least 95% liquid. Staff shouldn't hand one over until they're satisfied it clears that quantity, and a top-up, if you don't want the head, should never be refused.

That's the standard that the whole trade runs on. Pour a keg beer properly and consistently, and a keg's worth of liquid will legitimately stretch further in pints sold than it does in pints of liquid it physically held. A 5% head isn't a rip-off. It's the industry's own answer to a question the law walked away from.

So when a variance report shows a keg yielding 100%, or a touch over it, that's not a red flag, it's good control.

Part One of this series covered how a variance report gets built, line by line, into one overall number. This part we look under the bonnet to identify why a variance number on its own doesn't tell you anything until you know what "normal" actually looks like for that specific product. How normal isn't one number. That it's a different number for every category, and every one of those numbers has a real, physical reason behind it.

The formula stays the same throughout

Yield % = quantity sold through the EPOS ÷ quantity consumed from stock × 100

You can calculate this by whatever method you choose: pints, litres, bottles, or £'s.

It's the same calculation that we covered in Part 1 with the Guinness and bottled product examples. When it's calculated with revenue figures, these should include VAT, as this mirrors how your stock movements are calculated on your stock reports.

There are two versions of this figure worth knowing apart:

Yield before allowances doesn't take promotions into account, so a promo period shows up as a lower number here, measured against the full price on the stock report.
Yield after allowances (adjusted) does take promotions into account, because that lower revenue isn't the result of poor control, it's a controlled choice, and treating it as an allowance adjusts for that.

What changes, category by category, is what number you should actually expect to see come out the other end.

Cask Beer: around 95%

On a firkin, 72 pints, that works out to just under 4 pints lost. That's the allowance for tapping, venting, and the waste that's unavoidable at the end of a barrel. Lose more than that and it's worth investigating. Another way to say the same thing: 95% yield means selling 7.6 pints for every gallon (8 pints).

If casks are selling well, line cleaning shouldn't be adding much loss either. A cask turning over more than once a week means there's the opportunity to clean between casks and minimise waste rather than adding to it.

Keg Beers & Lagers: 100%, Sometimes a Little More

If the cellar's in good condition, cooling's working properly, lines are clean and dispense is consistent, keg beers and lagers should generally return a yield of around 100%. In some cases, they may produce a small surplus. A properly presented pint with a decent head (around 28ml, 1 floz) can add up across a full keg, meaning an 88-pint container may legitimately generate sales equivalent to around 92 pints.

That surplus is what usually offsets the unavoidable waste created by line cleaning. Taken together, those two factors are why 100% yield isn't an ambitious target for keg products, it's what a well-run operation with a good volume of sales should normally expect.

Turnover plays a major role, though. A fast-selling keg allows that natural surplus to work in your favour. A slow-selling keg does the opposite. The waste associated with line cleaning is largely fixed regardless of how much product is sold, so the fewer pints a product sells, the harder it becomes to maintain yield.

There's a quality consideration too. Suppliers generally recommend that a connected keg be sold within 5 to 7 days. Beyond that point, quality can deteriorate, and issues such as fobbing become more likely. Fobbing isn't just a quality problem, it's a yield problem too, increasing waste every time the product is poured.

This is why container size matters. Ordering a keg that's too large for the rate of sale slows turnover, increases the likelihood of quality issues and raises the amount of fixed waste relative to what's actually sold. Where keg products consistently underperform, turnover and ordering decisions are often the first places worth looking.

Draught Cider: 96 to 98%

The nature of cider means that you won't be generating a surplus on these products as there is no head retention. Converting well on this product means landing in that range specifically, a little better than cask beer, not just "roughly the same."

Guinness & Other Stouts

This is the one that surprises people. These products naturally return a yield over 100%, not under it. Surpluses of up to 4 pints could be anticipated on an 11-gallon container. 104% to 105% is a realistic target to aim for here specifically. Losing money on a product that could be generating a small surplus is a warning sign that you need to take note of because the baseline expectation is different to other beers.

Wines: Should Be Pretty Flat

Using government stamped stainless steel thimble measures, 125/175/250ml, there's no real reason to be sustaining losses here at all. Where variance does turn up on wine, it's usually the same cross-keying problem covered in Part 1: no till discipline, the wrong wine or the wrong glass size getting rung through, manufacturing a variance that was never really there.

Sparkling wine, prosecco specifically, is a different kettle of fish! Some of the loss may come from cocktails, where the prosecco pour isn't being measured to spec. But a major contributor can be sales by the glass. Prosecco's delicate so measuring it into a thimble and then pouring it into a glass spoils it, so pours by the glass where there is no line are usually done by eye instead. That's the same risk as free-pouring anything else, and it shows up as real shortages, especially at volume.

There's a genuinely good trick for this that doesn't involve touching the actual product to measure it. Fill a flute with a 125ml measure of coloured liquid, not prosecco itself, and leave it on the back bar as a reference. Line a real flute up against it, and pour until the level matches. Consistent pour, no thimble near the product, nothing spoiled and 125ml served.

Pre-Packed Products: 100%, No Exceptions

Bottled beers, cider, RTDs, bottled minerals, mixers, packets of snacks. No pouring, no head, no dispense process involved, so what goes in should come out exactly the same. If there's a shortfall here, the only real explanation should be breakage, a dropped bottle, not the kind of variation you'd expect from anything drawn through a line.

What Good Actually Looks Like, Pulled Together

"Well-controlled" isn't one number. It's hitting the right number for each product: around 95% on cask, 100% or a touch over on keg, 96 to 98% on cider, 105%+ on stout, close to flat on wine, and 100% on anything pre-packed. Miss any of these by more than the allowances already built into that target, more than the pre/post gap explained earlier can account for, and that's genuinely worth investigating, not just noting and moving on.

Why The Mechanism Matters More Than The Number

None of these numbers are arbitrary. Each one comes from something physical: foam, a government stamped measure. Understanding why each target is what it is means that you don't need a memorised list of percentages for every product. You can look at any drink you sell, work out what physically happens when it's poured, and reason out roughly what its yield should be, even one never mentioned in this piece.

I'm David Holden, with 30 years of experience across stock control, financial management, and internal audit, I help hospitality operators find exactly where profit is being made and lost.

Knowing what a good yield looks like is one thing. Achieving it consistently is another.

Every venue has products that quietly leak margin through overpouring, poor dispense practices, line issues, ordering decisions, or simple process problems. Most don't appear as dramatic variances, they show up as profits that never quite make it to the bank.

If you'd like a second pair of eyes on your stock performance, yields, and overall profitability, get in touch. I work with operators to identify where margin is being lost and put practical changes in place to put it back where it belongs.

Send me your stock report and I'll show you where I'd be looking first.

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