Pint to line or pint to brim: the markings a cup needs to serve beer

If a cup is used to measure the drink you sell, it stops being merchandise and becomes a measuring instrument. That single fact drives everything else on this page.

Line and brim, in plain terms

Two shapes of cup do the same job. A brim cup holds the measure when filled to the top. A line cup is slightly oversized and carries a line showing where the measure sits, which leaves room for a head on the beer.

Both are in ordinary use at bars and events, and both exist across the reusable event cup range. The choice is operational rather than legal: a line cup is more forgiving to pour into at speed, a brim cup uses less material for the same measure.

What the law calls them

In Great Britain, a cup used to measure and serve a drink is a capacity serving measure under the Measuring Instruments Regulations 2016. The GOV.UK guidance for those regulations sets out the capacities allowed for draught beer or cider: a third of a pint, half a pint, two thirds of a pint, one pint, two pints, four pints, eight pints and sixteen pints. Other liquids have their own list in millilitres and litres.

The marking requirement is written into the same guidance. A manufacturer must affix the relevant conformity assessment marking and the M marking "visibly, legibly and indelibly to the measuring instrument".

UKCA, CE, and what changed

This is where a lot of supplier copy is out of date.

Legislation in force from 1 October 2024 continues recognition of the CE marking for measuring instruments in Great Britain, and businesses can choose either UKCA or CE marking to place these goods on the GB market. In Northern Ireland the CE mark applies, with the CE and UKNI combination where conformity assessment was carried out by a UK approved body.

What has not changed is that the conformity marking travels with the M marking, and the marking set includes the year and the approved or notified body number. A cup that shows a bare logo and nothing else is not carrying the marking the regulations describe.

The crown is decoration now

The crown stamp goes back to 1698 as the declaration that a glass held an honest pint. It stopped being the conformity marking in 2006, when the EU Measuring Instruments Directive brought in the CE mark for this class of product.

Since then the crown has come back on a voluntary basis, and GOV.UK is explicit about its status: it "is limited to use as a decorative mark only and no meaning as to measurement accuracy should be inferred".

So a crown on a festival cup is a design choice. It says nothing about whether the cup measures what it claims.

What to ask a supplier

Three questions settle it. Which conformity marking does the cup carry, and does the M marking appear with it? Which approved or notified body carried out the assessment, and does its number appear on the cup? And is the capacity one of the measures allowed for the drink you are serving?

A supplier who can answer all three has a cup you can pour a pint into. One who answers "CE certified" and stops has told you close to nothing. Put the three questions in writing when you ask for a quote.