Why do the simple and advanced ABV formulas give different answers?
The simple formula ((OG - FG) x 131.25) is a linear approximation of a relationship that isn't actually linear — it drifts increasingly high above roughly 1.075 OG. The advanced formula accounts for how the density of an alcohol/water/extract mixture changes as fermentation progresses, which is why it tracks more accurately at higher gravities. At normal beer strengths (roughly 1.040-1.065 OG) the two formulas usually agree within a couple tenths of a percent.
Why do Tinseth and Rager give different IBU numbers for the same hop schedule?
They're two independently developed models of hop utilization — how much of a hop addition's alpha acid actually isomerizes into dissolved bitterness during the boil — built from different data and different assumptions about how utilization responds to boil time and wort gravity. They routinely disagree on the same schedule, the disagreement tends to widen on big, high-gravity, heavily late-hopped beers, and it isn't even always in the same direction — see Tinseth vs Rager: why they disagree for the worked numbers. Neither is simply "more correct"; brewing software and published recipes are inconsistent about which one they default to, which is exactly why seeing both matters.
How accurate are the hop, malt and yeast figures?
They're typical published ranges aggregated from grower, maltster and yeast-lab sources, not a single lab result for a specific batch. Alpha acid, in particular, genuinely varies by crop year and growing region for the same hop variety. Always check the current Certificate of Analysis or product data sheet for the exact ingredient you're using if precision matters for the batch you're brewing.
Is this site affiliated with any yeast lab, maltster or hop grower?
No. GravityBench is an independent reference and calculator site. Brand names (Fermentis, Lallemand, White Labs, Wyeast, Weyermann, Briess and others) are used descriptively to identify real commercial products and are the property of their respective owners.
Why doesn't this site tell me how much I should drink or how strong to brew?
Because that's not what it's for. GravityBench is about measurement and process control — getting a gravity reading right, a carbonation target right, a mash temperature right. What you brew and how you enjoy it is entirely up to you, within your local legal drinking age and homebrewing regulations.
Do I need to create an account to use the calculators?
No. Every calculator and every reference page is fully usable with no sign-up, no account, and no data sent to us. The only place you'd ever enter an email address is if you specifically choose to email yourself a result or subscribe to updates — both entirely optional.