I am total novice so please excuse me for possibly stupid question. I bought a "beer kit" (malt + hop) that had recipes for 20 and 12 liters. I decided to go for 12 liters, because I don't have a lot of bottles. So it says that I don't need to add priming sugar in case of 12L variant. I am now worried will not beer be flat then? The initial concentration of sugar is higher, but will not it be all processed before bottling? May be it is possible to start bottling before bubbling ends?

Edit: I am really sorry! I didn't read instruction careful enough and misinterpreted table. Here it is: enter image description here Priming sugar is marked as Sugar 2 (not Sugar 1 as I thought), so my original question doesn't make any sense anymore. Still thanks to everyone for very useful information.

3 Answers 3


This does sound like dangerous advice, unless they also tell you at which specific gravity to start bottling. If you bottle to early, you could get bottle bombs, and too late you get flat beer.

If you bottle at a SG close to the expected final gravity then you can reduce the chances of the above from happening. If you were going to use priming, sugar, for 2.5 volumes in 12 liters, you would use 3.2 * 2.5 * 12 = 96g sugar. (3.2 grams of table sugar gives 1 volume in 1 liter.) We can then extrapolate this back to a SG increase - table sugar is 36 gravity points per pound per gallon, or 8.314 * 36 = ca. 283 points per kilogram per liter. So the sugar would increase the gravity by 283*0.096/12 = 2.26 points. Since your extract beer kit is not 100% fermentable (unlike sugar) but probably close to 50-75% max, then you want to aim to bottle when the SG is at 2.26/0.75 = 3 SG above your final gravity. It depends upon the beer style - you could safely go up to 4 SG points above FG and end up with a well carbonated beer.

If the instructions don't tell you when to bottle or what the expected FG is, then I would simply let it ferment out and then bottle with priming sugar. It's safer and in many ways simpler than having to deal with all the guesswork about remaining fermentables in primary.

At 12 liters, the beer will be nearly twice as strong as the one at 20l, and possibly more bitter. You may want to simply get hold of some more bottles and brew the full 20 liters. Plastic 1.5 liter soda bottles work fine once cleaned (leave to soak for 24 hours in water then rinse and sanitize as usual.)

EDIT: In the comments, the OP realizes he's mis-read the instructions. The advice is then to follow the usual full ferment and add priming sugar - 96g in this case - as I recommended.

  • Instruction says when to bottle, I just don't have it with me. I think it was 1.010. So how do I know if I should add sugar in this case or not? Instruction explicitly states that I should not (in case of 12L variation). I want to make regular beer (4-5% alcohol), does it mean that I definitely should add water up to 20L? Is it possible to just add water in the middle of fermentation? Or at what point it is possible?
    – Andrey
    Commented Feb 4, 2013 at 13:23
  • I don't know what the strength of the beer will be - it depends upon the kit, how much syrup (extract) came with the kit and if you added additional fermentables. If the instructions state the SG when to bottle, then it seems fair to follow that guidance. You can add water half way through fermentation, but best to make sure you sanitize everything that comes into contact with it (or boil and leave to cool to room temp in a covered pan - in 2 or more batches if necessary if you don't have a pan large enough.) I would check the instructions to see what strength the 12l beer comes out at first.
    – mdma
    Commented Feb 4, 2013 at 13:49
  • I think strength was not mentioned in instruction, and that also confused me. The kit was 1L can with extract, I didn't add anything beside water. Yes, I think I will add water up to 20L, I really don't want strong beer and this clears a question about priming sugar and carbonization. Luckily my friend has a crate of empty bottles.
    – Andrey
    Commented Feb 4, 2013 at 14:01
  • Ah, if it's only 1l of extract, then please double check the instructions - the strength will be different and the instructions probably covers that. With 1l extract you probably have to add more sugar for the 20l. 1L of extract should be fine for a 12l brew, but 20l will mostly likely require additional sugar.
    – mdma
    Commented Feb 4, 2013 at 14:45
  • You are correct about sugar, that is exactly what instruction says. But this rises my initial question, if I brew 12L and don't add sugar, will my beer be flat then?
    – Andrey
    Commented Feb 4, 2013 at 15:21

If it was me I would let the beer finish out completely. Till the gravity reading stabilizes at what it was specified in the recipe. Then I would use the information from Palmer's book to determine how much priming sugar to add:


If you don't add priming sugar you most likely will end up with flat or under-carbonated beer. Use the nomograph to choose the amount for you. Notice it is designed for a 5 gallon batch so you will have to convert the units. This would be the best route.


I've brewed the Christmas beer and it was lovely, definitely not flat.

You do have to watch the gravity and bottle it when it says to though or you will get flat beer.

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