Appropriate calculation of ABV?

Hello,

I know of the easy method to calculate the approximate ABV, which is OG - FG x 1.3 (or 130).

I found a different way a while ago which is: ABW= (OG-FG) / (1.775-OG) x 76.08 and then ABV = ABW x FG / 0.794

As an example, my Apfelwein with the easy method (and temperature corrected densities): ABV = (1.060 - 1.005) x 130 = 7.15%

The more complicated way: ABW = (1.060 - 1.005) / (1.775 - 1.060) x 76.08 = 5.85%
ABV = 5.85 * 1.005 / 0,794 = 7.41%.

Although the difference isn't huge, I create an Excel file for each of my brews to keep info in and automatically calculate the ABV so I know what's it is at the end.

Thus, I am interested in knowing what is the appropriate way of calculating the ABV.

Thanks a lot,

mrfocus

I went to a couple of different online calculators, and the one I have in Beertools Pro and got two different sets of numbers between your low and high, so apparently there are a few different ways of figuring ABV, and they are not all exactly the same.

I'm sure that there's a very detailed calculation somewhere out there, but I'm far too lazy to go looking for it.

(OG-FG) * .131 works just fine for me.