Brown ale is a traditional British, top fermented ale. Flavor and color are very much like a pale ale, but sweeter and darker.
The Brewers Association (US) offers the following style parameters:
English-Style Brown Ale
"English brown ales range from deep copper to brown in color. They have a medium body and a dry to sweet maltiness
with very little hop flavor or aroma."
"Fruity-ester flavors are appropriate... ."
Original Gravity (ºPlato): 1.040-1.050 (10-12.5 ºPlato)
Apparent Extract/Final Gravity (ºPlato): 1.008-1.014 (2-3.5 ºPlato)
Alcohol by Weight (Volume): 3.3-4.7% (4-5.5%)
Bitterness (IBU): 15-25
Color SRM (EBC): 15-22 (30-44 EBC)
The BJCP offers the following style parameters:
11. ENGLISH BROWN ALE
Aroma: "Low to moderate malt aroma... (and) can include caramelly, grainy, toasted, nutty, chocolate, or lightly roasted. Little to no hop aroma."
Appearance: "Copper to dark brown or mahogany color. A few paler examples (medium amber to light brown) exist... Low to moderate off-white to tan head."
Flavor: "Generally a malty beer, although may have a very wide range of malt- and yeast-based flavors... (and) Can finish sweet or dry." "Low to moderate bitterness, enough to provide some balance but not enough to overpower the malt. Fruity esters moderate to none... and hop flavor low to none."
Mouthfeel: "Light to medium body... Sweeter versions may seem to have a rather full mouthfeel for the gravity."
Overall Impression: "A light-flavored, malt-accented beer that is readily suited to drinking in quantity."
History: "In modern terms, the name "mild" refers to the relative lack of hop bitterness (i.e. less hoppy than a pale ale, and not so strong)... the “mildness” may have referred to the fact that this beer was young and did not yet have the moderate sourness that aged batches had."
Ingredients: "Pale English base malts (often fairly dextrinous), crystal and darker malts... May use sugar adjuncts. English hop varieties would be most suitable, though their character is muted. Characterful English ale yeast."
OG: 1.030 – 1.038 FG: 1.008 – 1.013
IBUs: 10 – 25 ABV: 2.8 – 4.5% (most are 3.1 – 3.8%)
11B. Southern English Brown
Aroma: "Malty-sweet, often with a rich, caramel or toffee-like character... Very low to no hop aroma."
Appearance: "Light to dark brown, and can be almost black... Low to moderate off-white to tan head."
Flavor: "Deep, caramel-like malty sweetness on the palate and lasting into the finish... Hop flavor is low to non-existent... Moderately sweet finish with a smooth, malty aftertaste."
Mouthfeel: "Medium body, but... Low to moderately low carbonation."
Overall Impression: "A luscious, malt-oriented brown ale, with a caramel, dark fruit complexity of malt flavor."
History: "English brown ales are generally split into sub-styles along geographic lines. Southern English (or “London-style”) brown ales are darker, sweeter, and lower gravity than their Northern cousins."
Ingredients: "English pale ale malt as a base with a healthy proportion of darker caramel malts and often some roasted malts... English hop varieties are most authentic, though with low flavor and bitterness almost any type could be used."
Vital Statistics: OG: 1.035 – 1.042
IBUs: 12 – 20 FG: 1.011 – 1.014 ABV: 2.8 – 4.2%
Mann's Brown Ale (bottled, but not available in the US)
11C. Northern English Brown Ale
Aroma: "Light, sweet malt aroma with toffee, nutty and/or caramel notes."
Appearance: "Dark amber to reddish-brown color. Clear. Low to moderate off-white to light tan head."
Flavor: "Gentle to moderate malt sweetness, with a nutty, lightly caramelly character and a medium-dry to dry finish."
Mouthfeel: "Medium-light to medium body. Medium to medium-high carbonation."
Overall Impression: Drier and more hop-oriented that southern English brown ale, with a nutty character rather than caramel.
History/Comments: English brown ales are generally split into sub-styles along geographic lines. Southern English (or “London-style”) brown ales are darker, sweeter, and lower gravity than their Northern cousins."
Ingredients: "English mild ale or pale ale malt base with caramel malts. May also have small amounts darker malts (e.g., chocolate) to provide color and the nutty character. English hop varieties are most authentic."
Vital Statistics: OG: 1.040 – 1.052
IBUs: 20 – 30 FG: 1.008 – 1.013
SRM: 12 – 22 ABV: 4.2 – 5.4%