Oktoberfest beer is especially brewed for Oktoberfest by Munich's six oldest breweries.
While beer didn’t play a major role in the founding years of Oktoberfest, it became so dominant towards the end of the 19th century, that the whole festival is today often perceived as a beer fest. Although the hosts were originally supplied by brewers from outside of the city, especially from Bad Tölz, today Munich’s brewery profit from a legal monopoly. The breweries, which are allowed to sell their beer at Oktoberfest are defined in paragraph 63 of the Oktoberfest decree. Today, these are Augustinerbrauerei, Hacker-Pschorr-Brauerei, Löwenbrauerei, Paulanerbrauerei, Spatenbrauerei und Staatliches Hofbräuhaus.
The term „Oktoberfestbier“ is a trade mark. Therefore, these six breweries are also the only ones, which are allowed to produce Oktoberfest beer and they have to guarantee a minimum wort of 13,5%. Until 1872 this was completely different. The beer sold at Oktoberfest was the regular summer beer. The extraordinarily warm summer of 1872 lead to a shortage of summer beer at the Franziskaner-Leist-Bräu. In order, not to have to sell winter beer, the brewery decided to experimentally offer a new beer style, the amber-colored Märzenbier. The experiment with this stronger, but also more expensive beer, was so successful that it stayed for the next eighty years.
In the second half of the 20th century, Oktoberfest became brighter again. Hacker-Pschorr is the last brewery to call its Oktoberfest beer Märzen, which can easily be told by its darker color. “Braunbier”, literally brown beer, was only popular at Oktoberfest between 1840 and 1860. Before that time, the beer sold at Oktoberfest was even brighter than today. Contemporary witnesses even described it as wine-colored.