Every drink you pour over the bar has a legal size, and most of the rules are older than the people pouring them. Here's the short version for a UK pub: what you can serve, what you have to offer, what has to be on show, and one question landlords ask more than you'd think. Does the scale you use for your stocktake have to be trade approved? No, and I'll show you why.
The measures you can serve
These are the quantities allowed for drinks you pour yourself (not sealed bottles and cans), per the Trading Standards guidance on Business Companion:
| Drink | What you can serve | Doesn't apply when |
|---|---|---|
| Draught beer and cider | ⅓ pint, ½ pint, ⅔ pint, or multiples of ½ pint | It's mixed with another drink (shandy, lager top) |
| Gin, rum, vodka, whisky | 25ml or 35ml, or multiples of it | It's in a cocktail of three or more liquids, or the customer asks for a mix |
| Still wine by the glass | 125ml or 175ml, or multiples of either | Under 75ml, or mixed with another drink |
| Wine in a carafe | 250ml, 500ml, 750ml or 1 litre | |
| Port and sherry | 50ml or 70ml |
Two catches people miss. First, you pick 25ml or 35ml for gin, rum, vodka and whisky, and the same measure has to be used in every bar on the premises. You can't have 35ml in the lounge and 25ml in the bar. Second, the rule only covers those four spirits. Vodka is in, tequila isn't, so a 50ml shot of tequila isn't breaking this rule.
The small measures you have to offer
Separately, the mandatory licensing conditions say every pub has to have these available and tell customers they are:
- Beer or cider: a half pint
- Gin, rum, vodka or whisky: 25ml or 35ml
- Still wine in a glass: 125ml
"Tell customers" means on the menu, price list or other printed material they can see. If the wine list only shows 175ml and 250ml prices, that's the one that catches pubs out. The condition doesn't apply to drinks sold in a sealed bottle or can.
What has to be on display
- Spirits notice. A notice telling customers which measure you use, for example: "Gin, rum, vodka and whisky are served on these premises in 25ml measures or in multiples of 25ml."
- Wine glass sizes. On the menu, price list or a notice, for example: "Wine by the glass is served on these premises in measures of 125ml and 175ml, or in multiples of those quantities."
The kit Trading Standards actually checks
Your glasses and optics are what count as the legal measure, so they're what gets checked. Lined glasses, brim-measure glasses and optics have to carry the crown stamp, the CE mark or the UKCA mark. A brim glass has to be filled to the top, and a lined glass to the line. On a frothy pint, customers can ask for a top-up to a reasonable level. A free-pour spout on its own doesn't count as a measure.
Does my stocktake scale have to be trade approved?
No, as long as you only use it for your own stock control. The law on trade-approved scales (the green "M" sticker) only applies to equipment used "for trade". The Weights and Measures Act 1985 defines that as use in a transaction that is "by reference to quantity", where money changes hands and the scale is used to work out that quantity. A deli weighing cheese to charge for it is using its scale for trade.
Weighing your own open bottles to see how much gin is left isn't a sale, so nobody is being charged by what the scale says. Any decent kitchen scale that reads to the gram is fine for a stocktake. What matters for an honest count is using the same scale each time, zeroing it, and putting it on a flat surface. If you ever do start selling something by weight, ask your local Trading Standards first, because that's a different story.
That's how weighing part bottles works in StockTap: put the open bottle on the scale and type the grams. If StockTap doesn't know the bottle yet, you weigh one full, sealed bottle once, and it works out the empty bottle from the drink's strength.
The "pint of wine" that never really arrived
In December 2023 the government said shops could sell prepacked wine in a new 568ml "pint" bottle. It covers bottles in shops, not wine by the glass in pubs, so the 125ml and 175ml rules above didn't change.
The same announcement answered a public consultation on bringing back imperial units. It had 100,938 responses, and 98.7% of them wanted to keep buying and selling in metric. So nothing else changed: draught beer and cider stay in pints, and everything else behind the bar stays metric.
Sources
- Business Companion (Trading Standards), Selling alcohol in licensed premises: permitted quantities, the same spirit measure in every bar, notices, and stamped, CE or UKCA-marked equipment.
- The Weights and Measures (Intoxicating Liquor) Order 1988, article 3: 25ml or 35ml for gin, rum, vodka and whisky, and the mixture exemptions.
- Home Office, Guidance on Mandatory Licensing Conditions: the small measures that must be available, and making customers aware of them.
- Weights and Measures Act 1985, section 7: the meaning of "use for trade".
- GOV.UK, Choice on units of measurement: consultation response (27 December 2023): 100,938 responses, with 98.7% in favour of metric.
- GOV.UK, 'Pints' of wine stocked on Britain's shelves (27 December 2023): the 568ml size is for prepacked wine only.
- This is a plain-English summary, not legal advice. Your local Trading Standards or licensing team has the final word.