Figure out FG ?

[karljrberno]

Is there a way to determine what the FG Of you beer will be ?

I know there is factor all grain / extract any good reads on this how to determine

 

[Nateo]

There's no good way to accurately predict it before you brew, but you can find out for sure on each batch by doing this:
http://braukaiser.com/wiki/index.php/Fast_Ferment_Test

That will tell you your limit of attenuation.

 

[temptnmonkey]

if your OG is 1.060
and your attenuation is 75%

turn the 1.060 into 60, and the % into .75 and you can simply do the following formula

60 - (60 * 0.75) = 15 (don't forget to add the 1.0). so, the est. FG is 1.015 (and give or take a couple points).

There are many other formulas (variations on the same thing) and free/paid software that will do it for you available as well.

 

[Nateo]

Attenuation for brewer's yeast generally ranges from 65-85%, and could be 60-90% if using lots of simple-sugar adjuncts or lots of unfermentables. That's a big range. For a "normal" beer, with an OG of 1.060, the range would be between 1.09-1.021, which is so large as to be practically useless.

To just pick 75% attenuation as your estimate is a sure way to be wrong almost all of the time.

If you have specs for the yeast strain you're using, it's a good start. For instance, the expected attenuation for WLP001 is 63-70%, so the beer in our example would finish between 1.018-1.022, which is a much more reasonable range, but is still a larger range than I feel comfortable trusting.

 

[TopherM]

Hydrometer. Also, most recipes include the expected FG.

 

[Qhrumphf]

Only way to get a really good idea is to repeat recipe and same process, and even then it'll only work for that one brew and won't always be exact. I routinely get higher than any given yeast's attenuation ratings and drop lower than software's FG estimates by a few points. So I just adjust my recipes assuming that to be the case and it typically works out ok.

That said, I've found that extract/steeping grain recipes tend to be a bit more predictable than AG or PM recipes, as the grain and the mash add a bunch of extra variables to the equation. Not saying I know why or that that's always the case, just my experience.