Calculating ABV

I'm not sure if I'm understanding how to calculate abv. I just made my first batch ever and not sure if I'm reading my hydrometer correctly. From what I got it says my beer is 3.2 but gets me hammered after a few so I don't think I'm doing it correctly. How to I get and accurate reading? Whats the easiest way?

OG-FG/7.5=abv

I was told (og-fg) x 131 = abv% which gets about the same number as beerman0001 just doing it a different way

Example using formulas above:

(1.050-1.010) / 7.5 = .00533 or 0.53%
(1.050-1.010) X 131 = 5.24

I think Beerman meant to say (OG-FG)/0.75.

I have used the corrected formula to calculate my ABV

Is this like pi? 131.253141592654 lol

Brewnoob1 said:

Is this like pi? 131.253141592654 lol

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2 decimal places is all you need for accuracy, that's why everyone shortens pi to 3.14

Brewnoob1 said:

Example using formulas above:

(1.050-1.010) / 7.5 = .00533 or 0.53%
(1.050-1.010) X 131 = 5.24

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In my head .0053 meant 5.3% abv. You wouldn't expect a beer to have less than 1% unless you're making it alcohol free (or close to), but moving the decimal point sure makes it easier

Jayhem said:

(og - fg) X 131.25

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I didn't know/ forgot the .25. I can't even remember where I got 131 from to start with!

Jayhem said:

2 decimal places is all you need for accuracy, that's why everyone shortens pi to 3.14

Click to expand...

When we're dealing with reading a hydrometer by eye we're probably off a smidge anyway (I know my readings are 50% reading and 50% guesswork). I would take all abv calculations with a pinch of salt when homebrewing unless someone has more accurate equipment than a hydrometer, especially taking temperature of the OG and FG into account.

yes because i have read (OG-FG)105 to get the ABV. also i have a book that has a big chart that you look on one side for your OG then on the other for your FG and where they meet in the middle is your ABV. if you tell what your OG and FG are i will tell you what the chart says...

oh my equation of (OG-FG)105 comes from the book "Joy of Homebrewing" which i have been told by many people is the book to go off of. but hey i could be wrong..