There is no set size it is more of a tradition or cultural matter.
However in the UK there exists legislation as to how much liquid should be in a pint or half pint of lager or beer. The head is not classed as part of this liquid limit and should be in addition to the liquid. Generally about a centimetre is acceptable.
An Irish lager is a beer
Lager
in America it is lager
Budweiser, premium lager Bud Light, light lager Budweiser, Select light lager Bud Dry, dry lager Bud Ice, ice lager Bud Ice Light, light lager Michelob, premium lager Michelob Light low-carb, light lager Michelob Golden Draft, premium lager Michelob Golden Draft Light, light lager Michelob AmberBock, dark lager Michelob Honey Lager Specialty, honey lager Michelob ULTRA, low-carb light lager Michelob ULTRA Amber, light amber lager Busch Beer, lager Busch Ice, ice lager Busch Light, light lager Natural Ice, ice lager Natural Light, light lager Harbin Lager International, premium lager Rolling Rock, premium extra pale lager Anheuser World Lager, lager Bud Extra, specialty beer Bare Knuckle Stout Classic; Irish-style dry stout Stone Mill Pale Ale, organic pale ale Wild Hop Lager Organic, lager Bacardi SILVER, flavored malt beverage PEELS, flavored Malt Beverage Tequiza, fruit beer SPYKES, flavored malt beverage TILT, caffeinated malt beverage Hurricane, malt liquor Hurricane Ice, ice lager King Cobra, malt liquor 180 Blue, energy drink 180 Sport, sports drink 180 Energy, energy drink O'Doul's, non-alcohol O'Doul's Amber, non-alcohol Busch NA, non-alcohol
Gunnar Lager died in 1960.
Gunnar Lager was born in 1888.
John Lager died in 1961.
John Lager was born in 1887.
The population of Saint-Lager is 874.
Wrexham Lager was created in 1881.
Wrexham Lager ended in 2000.
Mildred Lager died in 1960.