GravityBench — Homebrewing Calculators & Reference

GravityBench exists because homebrewing runs on arithmetic that most calculators hide from you. Type in two gravity readings, get a percentage back, and you have no way to tell whether that percentage is right — or whether it agrees with the number your brewing software gave you, or the number a friend's spreadsheet gave you, or the number printed on the side of a commercial bottle at the same claimed strength.

Every tool here shows its work. The ABV calculator computes both the simple formula homebrewers have used for decades and the more accurate formula that accounts for how alcohol itself changes a gravity reading — side by side, so you can see where they agree and where they start to diverge as gravity climbs. The IBU calculator runs Tinseth and Rager in parallel, because those two widely-used formulas routinely disagree on the same hop schedule — sometimes by 20-30%, sometimes by well over that on a big beer, and not even reliably in the same direction — and knowing that in advance is more useful than a single confident-looking number.

This is a measurement site, not a drinking site. The subject is process control: reading a hydrometer correctly, converting a mash ratio, working out how much priming sugar turns into how much dissolved CO2 at a given temperature. Nothing here is about how much to drink or how strong you can push a batch — it's about getting the number right so the process behind it is predictable, repeatable, and safe (over-carbonation is a real bottle-safety issue, and the priming calculator says so explicitly).

Behind the six calculators sits a reference layer built the same way: real hop varieties with their published alpha-acid ranges, real malts with their colour and diastatic power, real yeast strains with manufacturer-published attenuation and temperature ranges, and BJCP-style guideline ranges for OG, FG, IBU, SRM and ABV across dozens of beer, cider and mead styles. Every figure states where it came from, because a wrong number in a calculator's input data is invisible to a reader — it just produces a wrong answer that looks exactly as confident as a right one.

Start with whichever number you're chasing today. If it's "how strong did this actually turn out," the ABV calculator has both formulas and an explanation of why they disagree. If it's "how much hop character am I actually going to get," the IBU calculator runs both standard formulas against your real schedule. If it's bottling day and you don't want bottle bombs, the priming calculator corrects for the CO2 already dissolved in your beer at whatever temperature it's been sitting at — a detail plenty of quick calculators skip entirely.