Have half a litre then. Speaking as someone from the only country that legally mandates beer in both pints (on draught) and metric (in bottles), I prefer a (UK, 20oz) pint if I'm drinking, because it's larger and I'm thirsty. For every other reason though litres are easier to reason about. The US 16 oz pint doesn't even have the benefit of being larger!
But usually in British pubs, beer is served in glasses that are a pint up to the brim, so if you are served beer with any head at all it’s probably closer to half a litre than a pint.
