BJCP 6C
A clean, crisp, delicately balanced beer usually with very subtle fruit flavors and aromas. Subdued maltiness throughout leads to a pleasantly refreshing tang in the finish. To the untrained taster easily mistaken for a light lager, a somewhat subtle Pilsner, or perhaps a blonde ale.
Served in a tall, narrow 200ml glass called a "Stange." Each Köln brewery produces a beer of different character, and each interprets the Konvention slightly differently. Allow for a range of variation within the style when judging. Note that drier versions may seem hoppier or more bitter than the IBU specifications might suggest. Due to its delicate flavor profile, Kölsch tends to have a relatively short shelf-life; older examples can show some oxidation defects. Some Köln breweries (e.g., Dom, Hellers) are now producing young, unfiltered versions known as Wiess (which should not be entered in this category).
Available in Cologne only: PJ Früh, Hellers, Malzmühle, Paeffgen, Sion, Peters, Dom; import versions available in parts of North America: Reissdorf, Gaffel; Non-German versions: Eisenbahn Dourada, Goose Island Summertime, Alaska Summer Ale, Harpoon Summer Beer, New Holland Lucid, Saint Arnold Fancy Lawnmower, Capitol City Capitol Kölsch, Shiner Kölsch
You can view the complete style details on the BJCP website. The 2008 style guide is obsolete but there is a similar 2015 style that you can view below...
OG: 1.044-1.050
FG: 1.007-1.011
IBU: 20-30
SRM: 4.0-5.0
ABV: 4.4-5.2%