Single Bottle Brewing

Ever wanted to take a small taste of a new recipe without dedicating an entire carboy to your new experiment? Did you know you can actually ferment batches smaller than 48 oz without wasting a lot of time and effort? Try fermenting right in the bottle! That’s right, no need to have a dedicated fermenter for sufficiently small batches when a bottle will do just fine. This tends to work best for extract recipes where you don’t need to worry about maintaining your mash temperature, as it can be a challenge with really small volumes of water. But don’t let me stop you from trying!

What you’ll need:

Extra equipment for brewing:

  • Scale accurate to ±0.1g. Better accuracy is preferable, but will cost more.
For fermenting:For bottling:

In terms of brewing, there isn’t much difference between these small batches and what you usually do for homebrewing. Below, I’ll go over some tips for making a successful single bottle brew.

Headspace Considerations

The first few times I tried single bottle brewing, I didn’t run into any issues. I mainly fermented pale ales with Safale US-05 yeast. I got no eruptions and my airlock remained clean. But note that I didn’t fill the bottle half-way up the neck like I usually do when bottling. Instead, I filled up to the point just before where the neck begins to provide additional headspace for the krausen.

When I bottle, I top it off with bottled water half-way up the neck like usual. But wait, doesn’t adding water dilute the brew and ruin it? As long as you take this into consideration while you boil, you’ll have no problems. This brings me to the next tip...

Boil Volume

For the boiling step, I usually take my target fermentation volume (for example, 16oz) and add about 16oz of additional water. Depending on how vigorous of a boil you use, you’ll lose anywhere from 12oz to 20oz of water to evaporation.

When boiling your wort, aim to boil down to a little less than your target fermenting volume. So if you’re fermenting in a 22oz bottle, you’ll want to boil down to about 19oz or so. This way, when you ferment, you’ll have plenty of headspace. Once fermenting is over, and you top off with bottled water, you’ll end up with the volume you were targeting as well as the right gravity (more or less).

Boil Time

For really small batches like this, I’ve found it unnecessary to do the full hour of boiling. Usually 30 minutes will be sufficient. If you want some extra boil time for your bittering hops to really shine through, 40 - 45 minutes should be sufficient.

Recipe Considerations

Before you go off to make your first single bottle brew, be cognizant of the yeast you’re using. When brewing a hefeweizen, the Munich wheat yeast that I used had a very aggressive fermentation that sent some krausen out of my airlock. I ended up needing to change out my airlock every 24 hours for 3 days.

For a situation like this, I recommend fermenting in a bottle one size larger than what you plan on drinking. This particular hefeweizen was in a 12oz bottle, but a 16oz bottle would have been more appropriate. When using a bottle larger than the bottling size, be sure to transfer to the properly sized bottle before capping, just like you would with a regular brew. One caveat of doing this is, if you’re using a siphon, it might not fit into your fermenting bottle. I usually just pour from fermenter to bottle when I need to, and I haven’t noticed any off flavors.


When you bottle, add the amount of corn sugar that you want, then top off with bottled water. The added water will help mix the sugar in. Shaking the beer to dissolve the sugar shouldn’t be necessary.

Also, if you feel like getting a single 12oz beer out of this isn’t worth it, try bottling with 7oz bottles. With a fairly full 22oz fermenter, you can squeeze out three 7oz bottles filled to about 6oz. Personally, I find this sufficient to taste test new recipes that I don’t intend to drink a lot of. These bottles can be hard to find, but I’ve rebottled Coronitas (7oz version of Corona) many times over without issue.

Dry Hopping

Just like in your usual fermenter, feel free to dry hop in the bottle. It will look kinda gross, but the flavor will not be negatively affected as long as you filter the hop particulate when you pour/siphon. I recommend placing a small muslin bag or cheesecloth over the bottleneck as you pour to capture the leftover hop matter.

Shorten Your Brew Day

For a “normal” brew day of ½ gallon or larger, I usually spend about 20 minutes setting up and sanitizing everything. When the brew is stoppered up in the carboy, there’s usually another 20 minutes of cleanup. With single bottle brewing, these times are reduced to 5 - 10 minutes, simply because there is less and/or smaller equipment to clean. If you’re also doing a shorter boil like I mentioned above, you can easily cut off almost an hour of time from your usual brew day.

Is single bottle brewing really worth it?

Now, I really love my small batches. Personally, I find rapid experimentation to be enjoyable, but I know it’s not for everyone. That said, there's the huge benefit of space savings. Not everyone has room in their apartment for a full sized brewing setup. For my situation, I don’t have a lot of room for my fermenters, so doing more than around two 1-gallon carboys at once is about my limit. With single bottle brewing, I can have 15 or more small batches bubbling away. Brewing smaller batches can make brewing beer more accessible to those with limited space to dedicate to the hobby.

If you have any questions or comments, feel free to email me: