Brewery Capacity Calculator
See how much beer your brewhouse and fermenters can make in a year, which one limits you, and how many tanks you need to grow.
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How brewery capacity works
Your brewhouse makes wort. Your fermenters decide how much of it becomes beer. A 1 BBL brewhouse that brews twice a week can make about 100 BBL a year, but only if you have enough fermenters to hold two weeks of beer at a time. Most small breweries run out of tank space long before they run out of brew days.
The math: fermenter capacity = number of fermenters × fermenter size × (days brewing per year ÷ days each batch spends in a tank). Brewhouse capacity is batch size × brews per week × weeks per year. You can only sell the smaller of the two, less your losses.
Rules of thumb for planning a small brewery
- Ales spend 10–14 days in a fermenter; lagers 3–5 weeks. A tank full of lager makes about half as much beer a year as the same tank running ales.
- Fermenters twice your batch size let you brew two batches into one tank (double-batching). That doubles output without a bigger brewhouse.
- Unitanks do more in one vessel. Ferment, crash, carbonate and serve from the same tank, with fewer transfers and less oxygen pickup. A separate bright tank can free a fermenter sooner if you run lots of ales.
- Plan for 8–12% loss between the kettle and the glass.
- Every fermenter needs cooling. Size your glycol chiller for all of them, plus any you plan to add.
Yearly output per fermenter
Based on 50 weeks a year, before losses.
| Fermenter size | Ales (14 days) | Lagers (28 days) |
|---|---|---|
| 1 BBL | 25 BBL | 12.5 BBL |
| 2 BBL | 50 BBL | 25.0 BBL |
| 3 BBL | 75 BBL | 37.5 BBL |
| 5 BBL | 125 BBL | 62.5 BBL |
| 7 BBL | 175 BBL | 87.5 BBL |
| 10 BBL | 250 BBL | 125.0 BBL |
Questions
How many barrels a year can a 1 BBL system make?
With 1 BBL fermenters and 14 days per batch, each fermenter makes about 25 BBL a year. Four fermenters and two brew days a week give about 100 BBL a year, or about 90 BBL after losses. That’s roughly 22,000 16 oz pints.
How many fermenters do I need?
Multiply the batches you brew each week by the number of weeks each batch stays in a tank. Two batches a week of an ale that sits for two weeks needs four fermenters. Add one or two spares for lagers, slow ferments and cleaning days.
What size brewhouse do I need for a taproom?
Start from what you expect to pour. A taproom selling 50 pints a day, 5 days a week, pours about 58 BBL a year once you allow for losses. A 1 BBL system with four fermenters covers that with room to spare; add fermenters as sales grow. Enter your own numbers above.
Should I buy unitanks or fermenters and bright tanks?
Unitanks ferment, crash, carbonate and serve from one vessel, so a small brewery needs fewer tanks and does fewer transfers. Bright tanks make sense once you brew enough ales that freeing a fermenter a few days early adds real capacity. See our Unitanks.
Does double-batching really double output?
When your fermenters are the limit, no; you’re still filling the same tanks. When the brewhouse is the limit, brewing twice into a fermenter twice your batch size doubles what each brew day produces. Try it above with Brews per brew day set to 2.