Märzenbier is German for “March beer,” a golden to deep amber lager style with a full body and a moderate bitterness, which is related to both the oktoberfestbier and the Vienna lager. The historical origins of märzenbier lie in a decree issued in 1553 by the Bavarian ruler Duke Albrecht V, in which he forbade all brewing between April 23 and September 29. The decree was to prevent brewing during the warm season, when, unbeknown to microbially ignorant medievals, ambient bacteria would often infect the Bavarians’ beers and quickly spoil them. See bavaria and infection. Brewers, therefore, worked overtime in March to make enough beer to last until fall. These March beers were usually brewed slightly stronger than regular beers and they were stored cool, that is, they were lagered, so they would keep better. See lager and lagering.

As a beer style, however, märzenbier became fixed only in 1841, when the Spaten Brewery of Munich introduced, at that year’s Oktoberfest, the first lager officially labeled märzenbier. See oktoberfest. That same year, the Dreher Brewery of Schwechat, near Vienna, also came out with a märzen-like beer, which it called Vienna lager. See vienna lager. In the ensuing decades, both the märzenbier and the Vienna lager became standard brews in the portfolios of many breweries; and by 1872, the Spaten Brewery first used the name Oktoberfestbier for a märzen-style beer, which it had brewed specifically for that year’s Oktoberfest. Today’s Spaten oktoberfestbier is still based largely on that 1872 recipe. In the 19th century, of course, these three related beer styles were all made by a double-decoction method, a very labor- and energy-intensive brewhouse procedure that many breweries no longer employ because of the modern availability of highly modified malt. See decoction.

Technically as well as historically, there is a great deal of overlap in the specifications of märzenbier, Vienna lager, and oktoberfestbier; and brewers around the world do not apply these designations consistently on their labels. However, the following general guidelines do apply in most cases. Much of the base malt in a märzenbier and oktoberfestbier, then and now, is so-called Munich malt, a highly aromatic malt with a color rating of roughly 10 to 25 European Brewery Convention (EBC; roughly 3 to 10 degrees Lovibond), whereas much of the base malt in the Austrian brew is Vienna malt with a lighter color rating of roughly 6 to 10 EBC (approximately 3 to 4 degrees Lovibond). See munich malt. As a result, the märzen and oktoberfest beers tend to be primarily golden amber in color, whereas Vienna lagers tend to have a more reddish tinge. Also, märzen/oktoberfest brews used to be much darker, nearly brown, in the olden days, but there has been a general trend in recent decades toward lightening them, an apparent concession to modern tastes. To North American beer enthusiasts this is often a surprise, because, ironically, North American craft brewers almost always brew märzen/oktoberfest beers to the old style, preferring a fuller color than that of the contemporary German versions. In terms of bitterness, the Vienna brew tends to be just a touch hoppier and drier than the märzen/oktoberfest, with the latter often showing sweet, almost toffee-like maltiness combined with biscuit and bread flavors, as well as plenty of mouthfeel.

In Germany, incidentally, the name Oktoberfestbier is now legally reserved only for the six breweries—Augustiner, Hacker-Pschorr, Hofbräuhaus, Löwenbräu, Paulaner, and Spaten—who may serve their beers at the Munich Oktoberfest. All other breweries may use just the märzen designation for their Oktoberfest-style beers. In other countries, of course, especially in North America, where German law does not reach, märzen/oktoberfest is treated like any other beer style and has seen a great surge of interest, especially in the emerging craft brew sector, although some craft brewers occasionally stray and brew the beer as an ale rather than a lager.