Fermentation calculators.
Six tools for home brewers of beer, mead, wine, and cider. Every formula is shown on the page, every citation is visible, and every result is printable.
The math, with sources.
Each calculator opens its own page with the math, a worked example, and the references the formula is drawn from.
ABV Calculator
From original to final gravity, with the formula and citations visible.
Open the calculatorHydrometer Temperature Correction
Adjust readings taken outside the hydrometer's calibration temperature.
Open the calculatorPriming Sugar Calculator
Bottle-conditioning sugar dose by beer volume and temperature.
Open the calculatorMead Must Builder
Honey weight and water volume for any target gravity.
Open the calculatorWine SO2 Calculator
Molecular SO2 from free SO2 and pH, with K-meta dose for any batch.
Open the calculatorCider Gravity Targets
Required OG and sugar addition for any cider style.
Open the calculatorWorking shown, sources cited, printable by default.
Most online brewing calculators give you an answer with no working shown. The point of building these from scratch was to do the opposite.
Every formula visible.
The math is on the page. Open the "How this is calculated" panel on any calculator and the equation, its derivation, and a worked example are all there.
Every citation linked.
Formulas come from primary sources — ASBC methods, Cutaia 2009, Boulton, Iland, Lea, Jolicoeur — and the source appears in the panel next to the equation.
Built to print.
Every calculator page has a print stylesheet. The result, the formula, and the citation print cleanly on A4 or Letter — tape it inside your brewery cabinet.
Eight more in the queue.
Subscribe to the cheat sheet list and you'll get a heads-up when each Phase 2 calculator goes live.
- Refractometer correction Universal
- Strike water temperature Beer
- IBU (Tinseth) Beer
- BU:GU ratio Beer
- TOSNA nutrient schedule Mead
- Wine chaptalisation Wine
- SG ↔ Brix ↔ Plato converter Universal
- Dilution and blending Universal
The calculators are derived from the books.
Five batch trackers across beer, mead, wine, cider, and a cross-craft master journal — under the R J Barley editorial byline. The back-matter references in each book are where these calculators come from.