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Before switching to Brewfather I ran my entire brewing operation on a Google Sheets spreadsheet, recipe calculations, water chemistry, batch logs, ingredient inventory, everything in one workbook. Building that spreadsheet took about four hours and it taught me more about brewing math than any book I’ve read, because every formula forced me to understand what it was actually calculating. Even if you use dedicated brewing software, understanding how to build a brewing calculator in a spreadsheet is worth doing once. Here’s how to set up the core calculations that cover 90% of what homebrewers need to calculate on brew day.
Core calculations to include
OG estimation from grain bill
The basic OG calculation: sum the points contribution from each grain (weight in lbs × PPG × efficiency / batch volume in gallons). PPG (points per gallon) is a malt-specific value, 2-row pale malt is 37 PPG, Munich malt is 35 PPG, Crystal 60 is 34 PPG. At 72% system efficiency, 10 lbs of 2-row in a 5-gallon batch: (10 × 37 × 0.72) / 5 = 53.3 gravity points = 1.053 OG. Build a table with grain name, weight, and PPG columns; the calculation row sums the contributions automatically as you add or change grain quantities.
IBU calculation (Tinseth formula)
The Tinseth IBU formula: IBU = (oz × AA% × Utilization × 7489) / Volume. Utilization is a function of boil time and wort gravity, higher gravity and shorter boil times give lower utilization. A simplified utilization table for 1.050 wort: 60 min = 0.241, 30 min = 0.189, 15 min = 0.131, 5 min = 0.050. Build a hop addition table with columns for hop name, oz, AA%, boil time, and calculated IBU. The total IBU row sums all additions. This is the same formula used in Brewfather and Beersmith, your spreadsheet results will match commercial software within 2–3 IBU.
ABV calculation
The standard homebrewing ABV formula: ABV = (OG – FG) × 131.25. For OG 1.052 and FG 1.010: (1.052 – 1.010) × 131.25 = 5.5% ABV. The more precise alternate formula: ABV = 76.08 × (OG – FG) / (1.775 – OG) × (FG / 0.794). The simple formula is accurate to within 0.2% ABV for most normal-gravity beers and sufficient for all homebrewing purposes. Enter OG and FG as inputs; the cell formula calculates ABV automatically.
Water chemistry worksheet
A water chemistry tab is the most complex but most valuable part of a brewing spreadsheet. The core structure: input your source water mineral analysis (Ca, Mg, Na, Cl, SO4, HCO3 in ppm), input batch volume, and calculate the mineral addition amounts needed to hit a target profile. Each mineral addition (calcium sulfate, calcium chloride, magnesium sulfate, sodium chloride) contributes specific ion amounts per gram per gallon, these are fixed values that you look up once and hard-code. The spreadsheet then calculates “add X grams of calcium sulfate to hit Y ppm sulfate.” Lactic acid and phosphoric acid additions for pH adjustment require a separate calculation based on water alkalinity and target mash pH. Bru’n Water (a free Google Sheets tool available from its author) is a fully built version of this that you can copy and use directly rather than building from scratch.
Batch log tab
A batch log records OG, FG, ABV, brew date, packaging date, tasting notes, and variations from the base recipe. After 20+ batches, patterns emerge: you can see whether your system efficiency is consistent, whether specific yeast strains reliably finish at the expected FG, and which recipe variations produced the best results. This data is more useful than any single batch result, it’s the accumulated record of your system’s behavior that allows systematic improvement.
Common Questions
Should I use a spreadsheet or dedicated brewing software?
Dedicated brewing software (Brewfather, Beersmith) is better for most brewers once you have more than 10 recipes, the yeast database, hop database, grain database, and equipment profile integration make recipe building faster than manual spreadsheet entry. A spreadsheet is better for: understanding the underlying math, building custom calculations that software doesn’t support, integrating brewing data with other spreadsheet-based tracking systems, and for brewers who want full control over every formula and assumption. The two approaches aren’t mutually exclusive, many experienced brewers use dedicated software for recipe design and a spreadsheet for batch logging and water chemistry, using each tool where it’s strongest.
