Scaling Recipes: From Small Batches to Larger Brews
Scale a recipe by keeping its proportions, not its weights. Here is how to scale grain, hops, water and yeast, with a worked example.
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The short answer: scale a recipe by keeping the proportions, not the weights. Treat the grain as percentages of the grist and hit the same original gravity at your system’s efficiency; scale hops to the same IBU; and recalculate water from your own boil-off and dead-space losses. Yeast scales with volume and gravity, and mash and boil times usually stay the same.
| Ingredient | How to scale | Watch out for |
|---|---|---|
| Grain | Keep each malt’s % of the grist; set the total for your target OG at your efficiency | Efficiency can shift a few points on a new system or a much bigger grain bill |
| Hops | Scale to the same IBU, not the same ounces per gallon | Bigger batches cool more slowly, so late and whirlpool hops add more bitterness |
| Water | Recalculate from your boil-off rate and losses | Boil-off is set by the kettle and heat source, not the batch size, so it doesn’t scale |
| Yeast | Pitch for the new volume and gravity | Use a starter or more packs |
| Times | Mash and boil times usually stay the same | Heating and chilling take longer |
Example: a 5 gal (19 L) recipe uses 10 lb (4.5 kg) of grain at 72% efficiency. At 10 gal (38 L) on a system that gets 68%, you need 10 × 2 × 72 ÷ 68 = about 21 lb (9.5 kg), split by the same percentages.
Step by step
- Compare like with like. “Batch size” can mean the volume in the kettle, into the fermenter or into the keg. Our recipe cards use the volume into the fermenter; check which your recipe uses.
- Work out the scale factor: new volume ÷ original volume. Going from 5 gal to 15 gal is × 3.
- Grain: turn each malt into a percentage of the total, then set the new total by gravity (next section) or with the efficiency ratio in the example above.
- Hops: multiply by the scale factor as a starting point, then check the IBU for the new volume in brewing software. Trim the late and whirlpool additions if the bigger batch takes much longer to chill.
- Dry hops, spices and fruit scale straight by volume: keep the same ounces per gallon or grams per litre.
- Water and yeast: rebuild them for the new batch (below).
- Brew, measure, adjust. Record your real efficiency and boil-off on the first batch and use them for the next.
Grain by gravity points
Gravity points are the part after the “1.0”: 1.050 is 50 points. Multiply by the gallons to get the points you need, then divide by what a pound of malt gives you. Pale malt yields about 36–37 points per pound per gallon if you extract every bit of sugar, so multiply that by your efficiency.
Example: 10 gal of 1.050 needs 50 × 10 = 500 points. At 70% efficiency, pale malt gives about 37 × 0.70 = 26 points per pound, so you need 500 ÷ 26 = about 19 lb (8.8 kg), split into the recipe’s percentages. Specialty malts yield a little less; software is more exact.
Water: why it doesn’t scale
Most water losses belong to your equipment, not the recipe:
| Loss | Depends on | Notes |
|---|---|---|
| Boil-off | The kettle and heat source | Measure yours in gal (L) per hour; the same element boils off about the same amount whatever the batch size |
| Kettle and mash dead space | Your equipment | A fixed volume |
| Trub and hop losses | The hop load | Grows with heavily hopped beers |
| Grain absorption | Grain weight | About 0.1–0.125 gal per lb (0.8–1.0 L/kg) for a drained mash; less if you squeeze a bag |
Work backwards from the volume you want in the fermenter: add trub and kettle losses, then the boil-off for the length of the boil, to get the pre-boil volume; then add grain absorption and dead space to get the total water. Water salts scale with the water you treat, not the beer, because they’re dosed in ppm (mg/L). If you brew on a Bräu system, the Brew Day Planner works out the water volumes, strike temperature and timings for your batch size.
Yeast
Pitch by cell count, not packs. Common yeast-lab guidance is about 0.75 million cells per mL per °Plato for ales and 1.5 million for lagers. 10 gal (38 L) of 1.050 (about 12.4°P) ale needs roughly 0.75 × 38,000 × 12.4 ≈ 350 billion cells, twice what it needs at 5 gal.
For dry yeast, one 11–11.5 g pack covers about 5 gal (19 L) of normal-strength ale, so use two for 10 gal, and more for lagers and strong beers. For liquid yeast, make a yeast starter.
Fermenting a bigger batch
A bigger batch has less surface for its volume, so it holds the heat of fermentation and runs further above room temperature. A room that kept 5 gal in check can let 20 gal run hot, so plan your cooling for the new size (see why fermenters heat up), and leave headspace for the krausen.
If you’re moving up, the Unibräu comes in 10, 20 and 30 gal sizes and the BräuPro in 5, 10 and 20 gal plus a 1 BBL version. Our recipes already scale from 5 to 30 gal.
Scaling down
The same rules work in reverse, but fixed losses hurt more: a quarter gallon (1 L) of dead space is 5% of a 5 gal batch and 25% of a 1 gal batch. Weigh hops on a scale that reads to 0.1 g. More in our guide to small batch brewing.
Frequently asked questions
Do I double the hops when I double the batch?
For bittering hops, that’s a close starting point; then check the IBU on your system. Late and whirlpool hops often need a little less in a bigger batch because it cools more slowly. Dry hops double.
Does the boil time change?
No. Keep the recipe’s boil time: it sets the hop bitterness and drives off DMS. If your system boils off more or less, change the starting volume, not the time.
Why is my gravity lower on the bigger system?
Almost always efficiency. Note the efficiency you actually got and use it next time. On the day, a little dry malt extract in the boil makes up a small shortfall.
Can I just add packs of yeast?
For dry yeast, yes. For liquid yeast, one pack rarely has enough cells for more than a small or low-gravity batch, so build a starter.
Do the math for you: our free recipe scaling calculator scales any recipe from 5 gallons to 1, 3 or 7 BBL, adjusts malt for efficiency, trims bittering hops and tells you how much yeast to pitch. Planning to sell it? See how to start a nanobrewery and run the numbers in the brewery startup cost calculator.
Related guides
Improving mash efficiency, IBU explained, yeast starters, mash tun dead space.