How to compute ABW and ABV by SG?

[asterix404]

So I have a question and I have read and found about 10 different answers... how do I calculate ABW and ABV from the SG reading?

I think that ABV = 1.25 * ABW

How do I calculate ABW from the SG reading in gravity points or the actual SG?

 

[beergolf]

I always just compute ABV

(OG - FG) x 131= ABV

 

[passedpawn]

OG = ABV

I.e.,

a 1.054 OG beer will be 5.4%
a 1.075 OG beer will be 7.5%
​

Pretty simple heh? (assumes attenuation of 76% by yeast, which is just about exactly what you will usually get).

 

[crazyseany]

the yeast attenuation... Is that what makes the difference in a beer & wine hydrometer?

you can use a wine hydromter to measure starting OG of beer but the abv scale will be off... Correct?

what is ABW?

 

[asterix404]

Well... attenuation being the actual attenuation or the apparent attenuation? For instance, I just made a heff which had an OG of 52 and ended at 8. It was like... 85% apparent attenuation, but something like 71% actual attenuation.

ABW is alcohol by weight and somewhere I read it was basically OG-FG * 105 or something and ABV is 1.25*ABW. I don't know however how to calculate ABW, I get a ton of different answers.

 

[beergolf]

OG = ABV

I.e.,

a 1.054 OG beer will be 5.4%
a 1.075 OG beer will be 7.5%
​

Pretty simple heh? (assumes attenuation of 76% by yeast, which is just about exactly what you will usually get).

It may be a good ballpark estimate that may get you close most of the time, but for certain brews it will be way off. For example I recently did a Saison that. was 1.062 but finished at 1.004 for an ABV of 7.6%

 

[passedpawn]

It may be a good ballpark estimate that may get you close most of the time, but for certain brews it will be way off. For example I recently did a Saison that. was 1.062 but finished at 1.004 for an ABV of 7.6%

Yeah sure. It's ballpark. I stated the assumption there.

 

[Yooper]

The easiest way to get ABV is by doing some simple math.

As was mentioned, ABV= (OG-FG) x 131 It's not exact, but it's very close.

ABW = (OG - FG) x 105