Experimenting With Bottle Carbonation Time

Here are the results of a quick bottle carbonation experiment. How long should you wait before putting your beer in the fridge?

bottle carbonation experiment

I recently received a comment on an old post about flat beer asking why a batch of home brew had failed to carbonate.

There was a key piece of information: the beer only had 4 days to carbonate before being put in the fridge.

I assumed that it had been chilled too soon, before carbonating properly. But after replying I realised I’d given advice based on instinct rather than experience.

So I decided to test the theory.

As I was about to bottle a batch of saison, I set up a mini-experiment. After priming the beer as usual, I added one bottle of it to the fridge every three days for two weeks.

Would the bottles that went in earlier be less carbonated and flat?

Carbonation Levels

I’ve written about priming sugar and carbonation before, so I’d suggest reading that if you don’t know what it’s all about.

For this beer, I added enough priming sugar for medium carbonation. That means I expected a reasonable but not excessive amount of gas and head.

Bottle Carbonation Experiment Results

To see the results, I poured all the beers straight into the centre of the glass, aiming for the most head possible.

In an attempt to generate suspense, I’ll go through them in reverse order.

Carbonated 15 Days/In Fridge F0r ½ Day

bottle carbonation time 15 days

The beer that had the full fifteen days at room temperature was nicely carbonated with a decent head and a pleasant gassy mouthfeel.

About right in terms of carbonation, although the beer itself needs a bit longer for some of the flavours to settle down.

Carbonated 12 Days/In Fridge For 3 Days

bottle carbonation time 12 days

This beer had carbonated too well. It looked like I’d overprimed it.

Carbonated 9 Days/In Fridge For 6 Days

bottle carbonation time 9 days

Although with less gas than the first beer, this was still OK and quite nice to drink.

This was the cut-off point I think.

Carbonated 6 Days/In Fridge For 9 Days

bottle carbonation time 6 days

Another overprimed one, an anomaly I think rather than a result to later be relied on.

It goes to show how variation from beer to beer is part of home brewing.

Carbonated 3 Days/In Fridge For 12 Days

bottle carbonation time 3 days

Just three days of carbonation at warm temperatures gave the beer enough time to develop gas and foam.

However, the head and fizz were short lived.

Carbonated 0 Days/In Fridge For 15 Days

bottle carbonation time 0 days

Unappetising and flat, the beer that went straight to the fridge seemed to confirm the theory. Bottle carbonation is best done at room temperature.

Something that hasn’t come through in the photos is the differences in colour. The 0 and 3 day beers were muddy orange/brown, whereas the more carbonated ones were bright and punchy yellow.

I hadn’t expected colour to be affected so much.


Although it may seem like there’s not a lot of difference, if you look at them all together you can see that the amount of head increases the longer they were carbonating outside the fridge.

Even the longer carbonated of the overly-gassy ones had more foam than its friend.

bottle carbonation time experiment

I’ve always treated two weeks as the minimum carbonation period and this test hasn’t changed my mind on that, even though you could probably get away with less.

The increased staying power of the foam convinced me it’s worth waiting the full fortnight.

There’s nothing particularly surprising about these results. In fact, here’s what the Yeast book says:

The way you store the beer also affects the degree of carbonation. If you store the bottles too cold, the yeast will not actively metabolize sugar and create CO2.

Although it was perhaps inevitable, it’s good to see my assumptions confirmed in reality.

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  1. Michael

    Hey John, I appreciate your commitment to experimentation. I have been thinking about doing a test to see if there is really any difference in the final product of a wort that has been boiled, and one that has not. I realise the implications for hop scheduling but I reckon I have had some better results dry hopping in the fermenter after a few days of fermentation, compared to boiling the crapper out of a hopped wort. Will also try hopping the mash for bitterness. Be interested to see how you would go if you’re keen. As you can appreciate, not having to boil the wort would be a major time and hassle saver. I guess the main issue would be the sterility of the non-boiled wort, but I’d be willing to give it a go.
    Cheers, Michael.

    • John

      Hi Michael,

      Thanks for the comment and the wild idea. It’d be great if that worked.

      I’ve always believed that apart from sanitising the wort, the boil generates hot break (and then cold break when it’s cooled) which helps clear the beer. It also drives off DMS which would taste like boiled vegetables (although I’ve never suffered from that thankfully). I guess this means darker, flavourful beers would be better suited to the technique.

      I’m also under the impression that hops have to be boiled in order to contribute bitterness, so perhaps the mash addition alone won’t be enough. Aroma should be much better in the unboiled beer of course.

      It’d be easy enough to do a trial batch by siphoning off some wort before carrying on with a regular brew. That’d give you some beer to compare the experiment with.

      I’m really intrigued by the idea and have added it to my list of things to try. Do let me know if you have any successes (or otherwise) in the meantime.



      • Basil

        Could do this with a sparge/second mash.

        Could put hops into the second mash of the grains for this and do as normal.

        I think your best bet would be to turn a beer into a 15minute boil, I do believe you’ll need at least _some_ boil.

        • John

          Thanks for the suggestion.

    • Ian

      Hi so stupid me put my beer in the fridge as soon as I bottled because I no read good. Any thoughts on how I could save it?

      • John


        You may be lucky and just bringing it out of the fridge to warm up for a couple of weeks will be enough.

        If that doesn’t work, I suppose you could empty the bottles back into the fermenter and add some more yeast before rebottling. You’d run the risk of infecting the beer doing that, so be careful about sanitation.

        • Dick

          Liquid yeast is kept in the fridge to keep them dormant and last longer. Fridging your beer should only make the yeast basically go to sleep, and warming them back up should wake the yeast up. This is theoretical, never done it myself. They will take longer to wake up and carbonate than usual though. Take the bottles out and let them sit for a month. Then fridge 1 for a week, open it, and check for carbonation.

          After, if you think you need yeast, make a yeast starter in a sanitized container with sanitized water. Then open each beer individually and pour a little yeast in and recap with new caps. This would be the best way to minimize the chance of contamination.

    • Hey Michael,

      You could buy a couple of those pasteurization indicators (WAPI) that you put into the substance you are trying to pasteurize and heat it until it indicates the proper temp then take the wort off the heat after that point. Or you could just look up what the temps and times are and use a good thermometer and take it off the heat at that point. Here’s a link to an Amazon product for reference on what I’m talking about in case you haven’t heard of it before.

  2. I think that was an experiment that was long overdue and thanks for taking the initiative to perform that experiment. You know there is more to this don’t you?
    We all want to drink carbonated beer as quickly as possible and maybe you already know the answer to this question. Can you carbonate faster by bottling and increasing the room temperature, say in a fermenter with a controlled atmosphere for a shorter amount of time? How bout that? Do you think it would work?

    • John

      Scott, thanks for your interest.

      I think it would work up to a point. I did this experiment in mid-summer with room temperatures around 25°C/77°F. In winter it would seem to make sense to store the beers warm, to mimic these conditions and encourage carbonation.

      However, at higher temperatures you may run into similar problems as in the fridge – that is that the yeast stop working. It would be interesting to test this out though.

      In any case, even if the carbonation was ready sooner I’ve yet to brew a beer that didn’t taste better after one month in the bottle.


  3. Excellent experiment. I think actually doing the experiment and documenting it demonstrates to new brewers the fundamentals rather than just telling someone to bottle condition for 2 weeks.

    If you can physically show someone that’s a lot better than telling them.

    I’m definitely a reader now and I hope to see more articles like this in the future!

    Alan @ http://www.how-to-make-beer.com

    • John

      Hi Alan,

      Glad you enjoyed the experiment.



  4. Hi,

    Unfortunately I read Your article after experimenting on my own, but better late than never :) I tested my 1st batch not because I planned to test, but mainly because of available space in fridge and my impatience.

    Anyway, my accidental test showed that there was not much difference between 3 days out-1week in; 6 days out – 6 days in and 10 days out – 1 day in. The difference was in taste – the last was the best, I thought this might be because of bottling too early and therefore in needed warmth to finish? And is this also possible that because of this, the carbonating was done equally well (since it was fermenting in bottle more than planned)?

    I will make another test soon, when my 2nd batch is ready to be bottled.


    • John

      Hi Rait,

      Your explanation sounds as though it could be right.

      If you bottled to early there would potentially be more sugar left for the yeast to work with. Also, the beer you left longer would have had time to condition and let the flavours settle a little.

      Thanks for commenting.

  5. Dick


    Another physical property you touched on here but may not have realized is Henry’s Gas Law. Gas dissolves into solution more readily at lower temperatures. The bottles at warm temperatures have created a CO2 buildup, but the CO2 is not in the beer at that time. Leaving the bottles in the fridge for at least a couple of days will allow the CO2 to dissolve into solution and thus carbonate your beer.

    To observe the effects of this, after bottle conditioning the bottles can be put in the fridge. Then each day after you can take one bottle out and observe the carbonation levels, particularly the really little bubbles. I haven’t done this yet, but there should be some difference according to the gas law.

    • John


      I didn’t know about that law but it’s interesting to hear about it. Thanks very much for the information.

  6. Carlos

    Thank you very much, that is what I was searching.

    • John

      Glad it was useful.

  7. Is the first time I’m making home beer I just finish bottle processes so I let the batch settle for a week then I did a chance in to a different container for another week then I bottle so how long should I let it seat on a temperature around 68℉ and 72℉ ??

    • John

      It will usually take about a month until the beer is “settled”.

      If you have a lot of bottles, I’d recommend trying one every few days so you get a feel for how the beer changes over time.

  8. Brandon Drury

    Any ideas as to why random bottles were overprimed? I’m having this same problem. Obviously, stirring in the sugar during bottling isn’t an option due to oxidation risks.

    • John


      Stirring isn’t great, but you can mix the solution in by racking the beer onto it. Are you doing that?

      Generally if you leave the beer twenty minutes or half an hour between adding it to the priming solution and bottling it mixes evenly.

      It’s not perfect so it’s usual there’s a little variation, but if there’s a big difference it sounds as though the solution is not mixed into the beer.


  9. Gustavo

    Gracias por tomarte el tiempo de realizar este experimento y compartirlo… me ha sido muy útil!

    Thanks for taking your time doing this experiment and share results. It is very useful! In addition you have generated a lot of constructive comments.

    • John

      De nada!

  10. April

    I am a newbie to home brewing. I made a batch of american light lager from Mr. Beer on April 9th.

    I know I should have waited two weeks to let it ferment, but I have final exams next week so I wouldn’t have time to taste test it and bottle it. So I went ahead and tasted it, and bottled it yesterday and it tasted like flat beer to me.

    Is there any chance of not having enough yeast to carbonate my bottles by not waiting the two weeks, or will I be fine?

    The temperature of the house is around 68-70 degrees. While the fridge temperature is about 34 degrees, whenever I am ready to put it in the fridge.

    Thanks for the pictures and info they were great examples of what to look for in carbonation.

    • John

      Hi April,

      You should be fine in terms of carbonation – the beer always seems flat at bottling time.

      If you bottled really soon you may end up with too much carbonation and even have exploding bottles (be careful). That’s because there could still have been sugar left in the beer that hadn’t been fermented out.

      Hope you enjoy the beer.

  11. Tdawg

    As the nerd I am, I want to say that you should try to limit the amount of variables in future experiments. For instance, try to keep the bottles the same amount of days in the fridge or vary the length they spend in the fridge.

    Apart from that, thank you for an informative article! :)

    • John

      That´s true, I suppose! In trying to keep the total time before drinking the beer constant, I’ve created two “variables”.

  12. Joe

    Hey guys, I am a first time brewer and read up a bit first.

    However, I got talked into using the kit instructions and when I mixed in the muscle malt stuff it turned into chucks of hard sugar almost like plastic. I then proceeded to ferment as I was worried I would get bacteria in there.

    It all seems to be bubbling away but slowed down drastically (two bubbles per minute) after 2 full days.

    Does this sound normal and is there anything else I should do to acount for my sugar problem?

    • John

      Hi Joe,

      I’m not sure about muscle malt, which I haven’t used, but certainly it doesn’t sound unusual for the bubbling to slow after two days.

      All being well, it should turn out fine.

      Good luck.