A - It seems the most common term for these things in the UK is 'beer mats' so that's what we generally go with, but 'coasters' is pretty popular too, especially over the pond in the USA.

In the United Kingdom, the small mats or plates used to protect a table surface from the heat or moisture of a glass or cup are almost universally referred to as coasters. While this term is standard, you might occasionally hear them called "beermat" in a pub setting, though "beermat" specifically refers to the disposable cardboard versions provided by breweries. In 2026, the term "coaster" remains the dominant noun across all social classes. Interestingly, for larger table-protecting items used under plates, the British typically use the term place mat rather than "charger" or "large coaster." If you are in a formal British home, "coaster" is the polite and correct word to use when asking for something to prevent a ring on the polished mahogany.