Help with calculations

[drinkindinkins]

I pulled these calculations from Designing Great Beers (great read btw) but they don't make any sense. Can some one help me out here?

Terminal gravity x 105 = alcohol by weight

ABW x 125 = ABV


The end results usually gives me a number in the 200s?

Thanks

 

[flars]

Had to look it up. Here is a link that will clear up those instructions.
http://www.beeradvocate.com/articles/518/

 

[Calder]

Try this.

Assume OG = 1.060, with a final gravity of 1.010

Difference is 0.050

0.050 x 105 = 5.25 (this would be the alcohol by weight, or 5.25% abw).

To get alcohol by volume, multiply by 1.25

5.25 x 1.25 = 6.5% abv.

No one really cares about abw, so I just go straight to abv. In this example, I take the 0.050 difference and multiply by 100. This gives 5.0 (this is done without thinking). Then I multiply this by 1.31 to get abv %.

5.0 × 1.31 = 6.55 %.

 

[drinkindinkins]

Ah perfect. Thanks!

 

[ncboiler]

(OG - FG)*131 = %abv