Beer Recipe Calculator - OG, FG, ABV, and SRM

A beer recipe calculator predicts original gravity (OG), final gravity (FG), alcohol by volume (ABV), beer color in SRM and EBC, calories, and Plato readings before brew day, from nothing more than a grain bill, batch volume, brewhouse efficiency, and yeast attenuation. The underlying math is the same across all-grain, brew-in-a-bag (BIAB), extract, and partial mash methods; only the typical efficiency and grain entries differ by method.

Batch size is the post-boil volume that goes into the fermenter, and pre-boil volume is what is collected before boiling begins. Brewhouse efficiency, entered as a percentage, sets how much of the grain's potential sugar actually ends up in the wort; typical values range from 65% for BIAB up to 80% for an experienced all-grain setup, and the default shifts with the chosen brew method. Each grain or fermentable in the bill contributes its weight, its PPG (points per pound per gallon), and its Lovibond color rating, so a built-in database of common malts can supply PPG and Lovibond automatically once a grain is identified. Yeast attenuation, entered as a percentage from a low (66%), medium (75%), or high (77%) preset or a custom value, sets how much of the available sugar the yeast is expected to consume, which drives the gap between OG and FG.

Results include OG, FG, ABV, SRM, EBC with a color preview, apparent and real attenuation, calories per 12-ounce serving, and Plato readings for both OG and FG. Two ABV formulas are available: a standard formula suited to most common beers, and the Hall Equation, recommended for high-gravity brews where the simpler formula understates alcohol content. Three color estimation methods, Morey, Daniels, and Mosher, let a predicted SRM be cross-referenced against more than one model rather than trusted from a single equation.

Predicting OG, FG, ABV, and color from an ingredient list turns recipe design into an iterative process, where grain quantities can be adjusted to hit a target before any ingredients are purchased. The same calculation covers a light session ale and a high-gravity imperial stout, changing only the inputs.

• All-Grain Recipe Design: Enter a full grain bill with mash efficiency to predict OG before purchasing ingredients, then adjust grain quantities until the gravity target matches the chosen beer style guidelines.
• Extract Brewing: Switch to extract mode and enter liquid or dry malt extract weights. The higher extraction efficiency of pre-made extracts is accounted for automatically, delivering accurate gravity estimates.
• BIAB Planning: The BIAB method preset uses a lower default efficiency, giving realistic gravity predictions for brew-in-a-bag setups that skip a separate sparge step.
• Color Estimation: Compare SRM values across the Morey, Daniels, and Mosher methods to verify a grain bill produces the color range expected for a target style, from light pilsner gold to opaque stout black.
• High-Gravity Accuracy: Switch to the Hall ABV formula for barleywines, Belgian quads, or imperial stouts, where the standard formula underestimates alcohol content.
• Recipe Scaling: Adjust batch size and pre-boil volume to scale recipes up or down; the grain bill's percentage breakdown helps maintain correct ratios when changing total weight.
• Yeast Selection: Compare how low, medium, and high attenuation levels affect final gravity and ABV to choose the right yeast strain for a desired flavor profile and alcohol level.
• Education: Gravity points, efficiency, and attenuation interact to determine the finished beer; a step-by-step calculation breakdown makes that interaction explicit for a new brewer learning the science behind recipe formulation.