A style guideline isn't a recipe — it's a target window that generations of brewers converged on, independently, because it's where a particular combination of malt character, hop character, yeast character and strength tastes balanced and recognisable as that style. Knowing the window matters whether you're brewing to a competition guideline, trying to reproduce a commercial beer you liked, or just deciding whether the numbers your calculators are giving you land somewhere sane.
Every style page here states the approximate OG, FG, IBU, SRM and ABV range as commonly summarised from the BJCP 2021 Style Guidelines, alongside a short description of the style's real character and history — where it came from, what defines it, and how it differs from its closest neighbours. These figures are general-knowledge approximations rather than a verbatim reproduction of the published BJCP document, so if you're brewing for a sanctioned competition, always check the current official guideline PDF directly rather than relying on any secondary source, this one included.
The categories run from clean, delicate lagers (American light lager through Bohemian pilsner and the malt-driven German lager tradition) through wheat beers, the whole Belgian family (from a modest blonde through the enormous, warming dark strong ales), the British ale tradition (mild through ESB), the stout and porter family (dry Irish stout through Russian imperial stout), the modern American IPA lineage (pale ale through double IPA and the hazy New England style), and the biggest, strongest styles in barleywine and Baltic porter. Cider and mead get their own entries too — neither has a conventional IBU or SRM range in most references, and those fields are genuinely left blank rather than filled with an invented number, because an honest gap is more useful than a plausible-looking guess.
Once you've picked a target style, the calculators here do the rest: the ABV tool tells you whether your OG/FG pair lands where the style expects, the IBU tool tells you whether your hop schedule is in range, and the SRM tool tells you whether your grain bill will actually produce the colour the style calls for.
Style categories are grouped on this hub the way most brewers actually think about them — lager, wheat, Belgian, British, stout/porter, IPA, strong ale, cider and mead — rather than the more granular numbered sub-style scheme BJCP uses internally for competition judging.