BrewCalc

About BrewCalc

BrewCalc provides free homebrewing calculators for extract, partial mash, and all-grain brewers. Calculate ABV, estimate bitterness, plan your mash water, figure priming sugar, and scale recipes.

All tools run in your browser. Share your brew day calculations via URL — send them to your brew buddy or save them for next batch.

ABV calculation: alcohol by volume is derived from the difference between original gravity (OG) and final gravity (FG). The simplified formula is ABV = (OG − FG) × 131.25; the more precise formula is ABV = (76.08 × (OG − FG) / (1.775 − OG)) × (FG / 0.794). A beer with OG 1.060 and FG 1.012 has approximately (1.060 − 1.012) × 131.25 = 6.3% ABV. The precise formula yields 6.4%.

IBU (bitterness) estimation: the Tinseth formula calculates International Bitterness Units as IBU = (oz hops × AA% × utilization × 7489) / batch volume in gallons. Utilization is a function of boil gravity and boil time — longer boils and lower-gravity wort extract more alpha acids. A 60-minute addition at 1.050 boil gravity has approximately 30% utilization; a 15-minute addition at the same gravity is around 13%.

Water-to-grain ratio for mashing: typical infusion mash uses 1.0–1.5 qt water per pound of grain (2.6–3.9 L/kg). Strike water temperature to hit a target mash temp accounts for the heat absorbed by the grain: Strike temp = (0.2/R) × (T_mash − T_grain) + T_mash, where R = qt water per lb grain. Thicker mashes (lower ratio) need hotter strike water; thinner mashes need cooler.

Priming sugar for carbonation: CO₂ volumes desired × batch volume determines the amount of priming sugar. Corn sugar (dextrose) formula: oz = (batch_gallons × desired_CO2 × 0.8095 − current_CO2) × 2. Target CO₂ for an American lager is 2.5–2.7 volumes; a Belgian saison might target 3.0–3.5. Residual CO₂ from fermentation temperature is subtracted before calculating priming additions.