OG -> FG = ABV Math

[PearlJam]

I know it is old, but I have in the short time that I have been brewing just took the difference in the last three digits divide by 7.62

ie

1.050 OG
1.010 FG

Diff = 40
/7.62
= 5.25% ABV

 

[Easycreeper]

For my own edification, does anyone know the cutoff in gravity which one would use the "alternate" calculation method as selectable on the Brewer's Friend calculator (outlined by @DV8DUG above)?

Thanks!