Hydrometer question

[Mead_head]

My hydrometer has a 5% next to the 1.040 reading. I was under the impression that if I wanted 5% beer I should go for 1.050 gravity. If someone could clear this up for me I'd appreciate it, thanks

 

[FatDragon]

Eight points = 1% ABV (right?)

So 1.040 will be 5% if it attenuates to 1.000 FG. Since most beers don't attenuate that low, you do indeed typically need a higher OG to get to 5% ABV.

 

[MindenMan]

That is the potential alcohol scale, not the proof calculator. The ABV is a different calculation. The FG is controlled by two things: 1) the OG of the wort, and 2) the attenuation of your yeast. For example let's say you want to use ESB London 1968 yeast which has an attenuation percentage between 67% and 71% (of the sugar in the wort) to brew your beer with. An OG of 1.054, will finish at an estimated 1.013, giving you an ABV of 5.2%. If this is confusing, download a free copy of "Qbrew" , and see what different yeasts will do to the same OG.

 

[helibrewer]

The easiest swag is this:

Alcohol Percentage shown for SG - Alcohol Pecentage shown for FG = approx. ABV

 

[FatsSchindee]

Another way to calculate it using the specific gravities is:
(OG - FG) X 131 = ABV

 

[boydster]

MindenMan is right on. You can use brewing software, or just find the typical attenuation range of the yeast strain you are using to figure out a target final gravity.

When you measure gravity at the beginning and end, you can simply do (OG-FG)x131 to figure out your actual ABV.

Edit: Late on the draw. Well played, FatsSchindee.