Bar cellar temperature: what you need to know

Last updated: 26 June 2026

Most pub licensees have no idea what temperature their cellar actually is—and they’re losing money because of it. You think you’re pouring a clean pint, but a cellar that’s too warm is leaking profit through every tap: flat beer, excess foam, line waste, and customer complaints that make people drink less. I’ve been running a Marston’s pub for 15 years, and I can tell you the difference between a cellar at 12°C and one at 16°C is the difference between knowing your stock numbers and guessing. Draught beer hides losses in poor cellar temperature and bad line cleaning waste—it’s the easiest place in your pub to lose a full GP point without noticing. This article covers what temperature your cellar actually needs to be, why it matters more than you think, and how to measure it in a way that ties back to your real numbers. You’ll also learn why most pubs miss this entirely when they count stock.

What is the ideal cellar temperature for beer?

The ideal cellar temperature for cask ales is 12–13°C; lager and keg should sit at 10–12°C. That’s not a suggestion or a nice-to-have—it’s the operating temperature at which beer is designed to taste right and pour properly. Below 10°C and you risk chill haze in real ales; above 14°C and you’re into flat beer, excessive foam, and a pour that customers will reject without finishing the glass.

Here’s what most pubs don’t realise: temperature variance is the enemy. A cellar that bounces between 11°C and 15°C every week is worse than one that sits consistently at 13°C, even if 13°C is technically on the warmer side. Consistency matters more than perfection. Your breweries know this. The bigger question is: do you?

If you’re serving cask ales (which most UK pubs are), 12–13°C is non-negotiable. If you’re running a mix of cask and keg, aim for the lower end of that range—10–12°C—and keep it there. A lot of pubs try to run one temperature for everything, which is a mistake. But a lot of pubs also have no thermometer in the cellar at all, which is a bigger one.

Why cellar temperature affects your profit

Temperature drives three things in your cellar: beer quality, line waste, and stock accuracy. Miss on any of these and your GP takes a hit.

Beer quality and customer rejection

Warm beer tastes flat. It pours with too much head. Customers send it back. You pour it down the drain. That’s pure loss—the till recorded a sale that went to waste, and your stock count will be off unless you’ve recorded it. Most pubs don’t. A 1% stock loss on wet sales quietly costs a typical pub £3,000–£5,000 a year. Cellar temperature is one of the main drivers of that loss.

Line cleaning and chemical waste

When a cellar runs too warm, beer lines degrade faster. You have to clean them more aggressively and more often. That means more caustic soda, more water waste, and more frequently you’ll have to throw away a partial line of product because it’s been sitting there too long. A cellar at 16°C instead of 12°C forces you into extra cleaning cycles. That’s not free.

Hidden foam waste

This is the one I see most often. A warm cellar pours beer with too much foam. The barstaff compensates by topping up the pint—giving away an extra half-inch “for the foam.” Over a week, that’s a full barrel’s worth of free beer, recorded as sold but never paid for. If your variance sheet says you’re 2–3% down on draught but your till is balanced, warm cellar is probably the culprit.

How to measure and monitor cellar temperature

You need a thermometer. Not a vague guess. Not “it feels about right.” An actual thermometer, placed in the coldest part of your cellar (usually away from the door and away from the pump), checked and recorded every week.

What thermometer to use

You have two options: a simple wall-mounted dial thermometer (£5–10, accurate to 1°C, need to check it manually) or a digital min/max thermometer (£15–30, shows you the highest and lowest temperature over a given period). For most pubs, a dial is enough. For pubs that struggle with temperature variance, a digital one is worth the extra money because it shows you if something broke overnight—a blocked vent or a failed cooler unit.

Place it in the coldest spot in the cellar. Not next to a radiator. Not in direct sunlight from a window. Not next to the pump (heat rises from the motor). Check it the same day you do your weekly count. Write it down.

Tie it to your stocktake

This is important: temperature only matters if you reconcile it against your stock numbers. A StockTap pub stock app or even a simple spreadsheet should have a column for cellar temperature recorded on the same day as your line check and weekly variance count. When you see a variance spike, you immediately know whether it coincides with a temperature spike. Most pubs that do this catch temperature issues within a fortnight instead of losing money for months.

Common cellar temperature mistakes

Cellar is too warm because the door is left open

This is the single most common cause of warm cellars in UK pubs. Someone propping the door open while they’re restocking, or leaving it open during a delivery. Temperature can spike 3–4°C in 20 minutes. Train your staff to close the door immediately. If your cellar is upstairs or awkward to access, you’ll have more door-opening events. That’s a real cost.

Thinking the brewery’s stocktaker will catch it

The brewery stocktaker comes every 2–4 weeks. By then, a temperature problem has already cost you. And no stocktaker is going to measure your cellar temperature. That’s your job. You’re the one who can spot a pattern and act on it. The brewery is counting product; you’re running the business.

Over-relying on the cooler unit’s thermostat

Cellar coolers have thermostats, but they don’t always work accurately. They also only measure the air coming out of the unit, not the temperature in the corners of the cellar where your casks are sitting. Check the actual temperature in the cellar, not just what the cooler says it’s set to.

Running the cellar too cold to “be safe”

Some licensees run cellars at 8–9°C thinking it’s safer. It’s not. It introduces chill haze, slows the pour, and can damage real ales if the temperature fluctuates. You’re not improving quality; you’re just wasting money on extra cooling. Stick to the range.

Temperature and stock control: the connection most pubs miss

Here’s the operator insight that only someone who’s actually run a pub would understand: most pubs miss the connection between cellar temperature and stock accuracy. You do a weekly count. Variance comes back at 1–2%. You assume it’s theft or spillage or staff drinking. Often, it’s actually a combination of slightly warm cellar (which creates foam waste you haven’t measured), slightly aggressive line cleaning (which removes product you’ve forgotten to record), and a Tuesday when someone topped up a few pints without ringing it through.

The number that actually matters is wet GP by line, not a single headline stock figure. If you’re running cask ale, draught lager, and spirits, you need to know the variance for each one separately. A 2% loss on spirits is a big problem. A 2% loss on draught might be normal if your cellar is warm or your lines aren’t being cleaned properly. You can’t tell the difference unless you’re measuring temperature alongside your count.

At 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. The first thing I did was add a cellar thermometer to that routine. Within a month, I realised my draught variance was driven mostly by temperature swings, not loss. Once I tightened temperature control, variance on cask dropped from 1.8% to 0.8%. That’s nearly £1,000 a year on a single line.

Most pubs that move from a messy spreadsheet to a disciplined count—including a weekly temperature check—claw back 1–2 GP points within a couple of months. You’re not actually earning more money; you’re just stopping money from leaving the business.

For more information, visit SmartPubTools.