Brewing Formulas

How to Calculate Brewhouse Yield, Tank Utilization, and Distillation Energy

A working guide to the core brewing and distilling calculations, from brewhouse yield to distillation energy, with real units and worked examples.

Brewhouse yield, sometimes called extract efficiency, tells you how much of the sugar locked in your grain actually reached the kettle. The working formula is brewhouse efficiency = (gravity points times post-boil volume in gallons) divided by (grain weight in pounds times grain potential in points per pound per gallon). Two-row base malt runs about 37 PPG, wheat near 39, and crystal malts 33 to 35. Pull those potential figures from the maltster spec sheet, not memory, because a 2 PPG error across a 500 lb grain bill shifts your result by roughly 3 percentage points and quietly rewrites your recipe cost.

Work a real batch. A 50 lb bill of two-row at 37 PPG gives 50 times 37 = 1,850 point-gallons of potential extract. You collect 30 gallons post-boil at an original gravity of 1.052, which is 52 gravity points. Actual extract is 52 times 30 = 1,560 point-gallons. Brewhouse efficiency is 1,560 divided by 1,850 = 84.3%. Run the same inputs through the Brewhouse Yield calculator and confirm the volume was measured cold, since hot wort reads about 4% larger and will inflate your yield by 3 to 4 points if you skip the temperature correction.

Fermentation Tank Utilization measures how hard your cellar works. Utilization = occupied tank-days divided by available tank-days. Ten fermenters across a 30-day month give 300 available tank-days. If a typical batch holds a tank for 12 fermentation days plus 2 days for crash, transfer, and cleaning, each cycle is 14 tank-days. Suppose your tanks logged 249 occupied days that month. Utilization is 249 divided by 300 = 83%. The 17% gap, about 51 tank-days, is turnaround and idle time, and every idle day on a 500 L vessel is roughly 500 L of beer you did not make.

Distillation energy starts with the heat balance Q = m times c times delta-T for warming the wash, then adds latent heat to boil off spirit. Water has a specific heat of 4.18 kJ per kg per degree C and a latent heat of vaporization of 2,257 kJ per kg. Heating 1,000 kg of wash from 20 to 95 degrees C takes 1,000 times 4.18 times 75 = 313,500 kJ, or about 87 kWh, before a single drop distills. Vaporizing 150 kg of that charge adds 150 times 2,257 = 338,550 kJ, another 94 kWh. Feed both stages into the Distillation Energy Cost calculator.

Convert that heat to money with fuel price and boiler efficiency. The run above needs 313,500 plus 338,550 = 652,050 kJ of delivered heat, near 181 kWh thermal. A gas boiler at 80% efficiency actually burns 181 divided by 0.80 = 226 kWh of gas. At natural gas around 0.07 dollars per kWh, that is about 16 dollars of fuel for the batch, before any reflux or stripping run. Divide by liters of pure alcohol produced to get energy cost per LPA. If the batch yields 55 LPA, energy runs about 0.29 dollars per LPA of delivered spirit.

Alcohol Loss Estimate captures spirit that never reaches the bottle. Two sources dominate. Barrel aging loses the angels share, about 2% of volume per year in cool Scotland and 4 to 8% in hot Kentucky rickhouses. Fermentation and transfer strip more through CO2 venting and tank heels. If you barrel 200 liters of pure alcohol and lose 4% in year one, that is 200 times 0.04 = 8 LPA gone. Over a 4-year age at 4% compounding you keep 200 times 0.96 to the fourth power = 170 LPA, a 15% cumulative loss you must price into every cask.

Fill Level Giveaway is the quietest leak on the packaging floor. Giveaway per unit = mean actual fill minus target fill. If your target is 330 mL but the filler averages 333.5 mL to stay above the legal minimum, you give away 3.5 mL per can. Across 2 million cans a year that is 7,000 liters of finished beer poured for free, worth 14,000 dollars at 2 dollars per liter of cost. Tightening the filler to a 1.5 mL mean overfill with a lower standard deviation recovers most of it. The Fill Level Giveaway calculator turns fill-weight scatter into annual dollars.

Two rate calculations close the loop. Packaging Line Efficiency = actual output divided by (rated speed times scheduled run time). A canning line rated at 400 cans per minute over a 400-minute shift could theoretically produce 160,000 cans. Fill 128,000 and efficiency is 128,000 divided by 160,000 = 80%. Keg Fleet Turns = annual keg fills divided by fleet size, so a 5,000-keg fleet filled 22,500 times a year turns 4.5 times. Both feed capacity planning directly, and both reward you for cutting the changeover and dwell time that the Cleaning Cycle Downtime calculator quantifies.

Published 2026-07-02.