I'm confused, How do I get the ABV of mybrew

I thought I could make a quick little post with a simple accurate formula for getting a brews ABV so I can just plug in my numbers and not have to do math. But I cant seem to get a simple accurate formula, I have found multiple formulas. The question becomes witch to use.

The simplest formula I have found is ABV = (og – fg) * 131 but from what I have read  isn't the 100% accurate. Below I'll outline all the formulas I found and apply them to the brew I just bottled.

My Brew is a Belgian farmhouse Ale with a OG: 1.072 and a FG: 1.013 the results range from 7.73% to 8.15 % alcohol, I guess a difference of  0.4% is a lot.

1) According to BrewersFriend this is the two most popular formulas
Basic Formula: = (og – fg) * 131.25
Alternate Formula: = (76.08 * (og-fg) / (1.775-og)) * (fg / 0.794)
2) Wikipedia has a couple formulas
Standard Formula: = (1.05/0.79) * ( (og – fg)/ fg) * 100
Basic Formula: = (og – fg) * 131
3) Homebrew Stackexchange has a a bunch of formulas listed in this question
Formual: = ((76.08 * (og - fg) / (1.775 - og))
Basic Formula 1: = ((og - fg)/.75) * 100
Basic Formula 2: = (og - fg)*131
4) Beer Advocate has similar formula on one of it post, this is really just a place holder for a bunch of different sites, everyone seems to use this formula.
Formula: = (og – fg) * 131