How much yeast for a 5 gallon batch of beer?

How Much Yeast Do You Really Need for a 5-Gallon Beer Batch?

When brewing a 5-gallon (19 L) batch of beer, one of the most common questions homebrewers ask is: How much yeast should I use? The answer depends on what you're brewing—ale or lager—but a good starting point is a single 11-gram packet of dry yeast.

That small pouch contains roughly 200 billion yeast cells, which is typically sufficient for fermenting a standard 5-gallon batch of ale. Most ales are forgiving, and this cell count gives a solid, healthy fermentation without off-flavors or delays.

Lagers, on the other hand, are a bit more demanding. While one packet might technically get the job done, many brewers—and brewing experts—recommend using two packets for a cleaner, more reliable fermentation. Why? Lager yeast works at cooler temperatures and requires a higher cell count to start strong and finish cleanly. Under-pitching can lead to sluggish starts, stuck fermentations, or unwanted esters.

Another factor to consider is original gravity. If you're brewing a high-gravity beer—like a barleywine or imperial stout—even ales may benefit from a yeast starter or an extra packet to ensure a robust fermentation. Dry yeast is relatively inexpensive, so when in doubt, it’s often better to pitch a little extra rather than risk under-pitching.

Ultimately, for most 5-gallon ale recipes, one 11 g pack of dry yeast is more than enough. For lagers or stronger beers, playing it safe with two packets—or rehydrating the yeast properly—can make a noticeable difference in flavor and fermentation time.

As with all aspects of brewing, consistency and attention to detail matter most. Choose the right yeast strain, pitch at the correct temperature, and give those billions of hardworking cells what they need to turn wort into something worth drinking.