how to calculate ABV

[the complete angler]

Hi guys, this might seem a stupid question but how do I calculate the % of alcohol from my hydrometer readings

Mike

 

[Cononthebarber]

Look at the top left of the screen where it says calculators, you will find all you need there :thumb:

 

[Dave1970]

Use the calculators link top left of your page...go to the ABV calculator (top one)...put in Original Gravity and Final Gravity...it'll tell you the ABV... :thumb:

 

[Fireball13801]

You just need to use the ABV calculator in the top left of this forum. You need the OG (original gravity the hydrometer reading from before the 1st fermentation began) and the FG (hydrometer reading before bottling or kegging) for example an OG of 1044 & a FG of 1010 means you have a 4.5% brew.

Hope this helps.

Good luck. :thumb:

 

[morethanworts]

Use the calculator, or use (OG-FG)/0.0074 (Ken Shales)

You can also work out the relatively small ABV contribution from the priming sugars [unless the calculator makes a forward guesstimate for that. Mods??? Probably doesn't].

Base the priming sugars calculation on 18g of cane sugar producing 1%ABV in 1 litre. Scale that up for your brew, but also adjust for the fermentability of your primer if you're not using normal white sugar. As a guide, 80g adds very near 0.2%ABV in a 23 litre brew. Considering our calculations are still going to be slightly inaccurate, I do at least calculate the priming sugar addition, just to be as close as I can reasonably be.

We'll never get a totally accurate ABV at home without far more sophisticated processes, which can involve burning off the alcohol and replacing it with water and all sorts...I think...

I don't think most folk around here are TOO fussy about ABV as long as it's suitable for the style and the beer tastes good!

 

[dzlater]

(og-fg)*131=%ABV

 

[BreadMurderer]

Not to high jack this thread but... how to you calculate additional alcohol added? For example adding rum to my oatmeal stout?

My initial thoughts were to calculate the amount (roughly) of rum in ml's for each 500ml bottle then work out the actual amount of alcohol within that measure of rum. THEN work out the actual amount (in ml's) of alcohol given by the beers ABV, add this to the rum value and that would be the percentage of the final beer...

Does that make any sense at all?

 

[oldbloke]

Not to high jack this thread but... how to you calculate additional alcohol added? For example adding rum to my oatmeal stout?

My initial thoughts were to calculate the amount (roughly) of rum in ml's for each 500ml bottle then work out the actual amount of alcohol within that measure of rum. THEN work out the actual amount (in ml's) of alcohol given by the beers ABV, add this to the rum value and that would be the percentage of the final beer...

Does that make any sense at all?

Not only makes sense, also only way to do it, I think (though the morning coffee's not really kicked in yet)

 

[evanvine]

Use the calculator, or use (OG-FG)/0.0074 (Ken Shales)

(og-fg)*131=%ABV

These appear to be strange figures!
For a 40 gravity point drop:-
MTW’s would give 5405%
DZ’s would give 5240%

I think there are some decimal points missing or in the wrong place!

Try (OG-FG)/7.54, or (OG-FG)*0.133
Both will give 5.3%

 

[dzlater]

1.050-1.010=.04
.04*131=5.24
5.2% abv
:thumb:

 

[morethanworts]

Use the calculator, or use (OG-FG)/0.0074 (Ken Shales)

(og-fg)*131=%ABV

These appear to be strange figures!
For a 40 gravity point drop:-
MTW’s would give 5405%
DZ’s would give 5240%

I think there are some decimal points missing or in the wrong place!

Try (OG-FG)/7.54, or (OG-FG)*0.133
Both will give 5.3%

:hmm: Not sure how you get this!!! I said (as quoted) Use the calculator, or use (OG-FG)/0.0074 (Ken Shales). A typical 1.042 OG minus a typical 1.012 FG = 0.03 which, divided by 0.0074 gives 4.05. No errors with decimal points at all!

dzlater's would give 0.03*131 = 3.93. No errors on his/her part either with decimal points. You could go into the slight difference in the exact sums, but I don't see any problem with the decimal points. And yours would give a result that starts with two zeros after the decimal point: (OG-FG)/7.54 would be (in my example) (1.042-1.012)/7.54=0.00397, which would need to be multiplied by a thousand to give an ABV figure (3.97).

 

[BreadMurderer]

Not to high jack this thread but... how to you calculate additional alcohol added? For example adding rum to my oatmeal stout?

My initial thoughts were to calculate the amount (roughly) of rum in ml's for each 500ml bottle then work out the actual amount of alcohol within that measure of rum. THEN work out the actual amount (in ml's) of alcohol given by the beers ABV, add this to the rum value and that would be the percentage of the final beer...

Does that make any sense at all?

Not only makes sense, also only way to do it, I think (though the morning coffee's not really kicked in yet)

Glad my brain still works then, cheers! :thumb:

 

[evanvine]

:hmm: Not sure how you get this!!! I said (as quoted) Use the calculator, or use (OG-FG)/0.0074 (Ken Shales). A typical 1.042 OG minus a typical 1.012 FG = 0.03 which, divided by 0.0074 gives 4.05.

Ah! I see my confusion!
I read 1.042 as 1042 and 1.012 as 1012.
So 42 - 12 = 30 gravity points.
My less clumsy figures then work!

 

[Cononthebarber]

I was also confused by that as I didn't put the decimal point in the OG and FG figures giving a huge ABV :lol:

Makes perfect sense now :thumb:

 

[Leemond]

1.050-1.010=.04
.04*131=5.24
5.2% abv
:thumb:

Is 1.050 a reasonable OG reading? It's what today's brew has come out at...

 

[Jenn3012]

Use the calculators link top left of your page...go to the ABV calculator (top one)...put in Original Gravity and Final Gravity...it'll tell you the ABV... :thumb:

I am getting different results every time i check my final gravity, seems there is some error. Anyways thanks Dave!

 

[kelper]

Or subtract FG from OG and multiply by 1.3125.

 

[Cheshire Cat]

Or subtract FG from OG and multiply by 1.3125.

No that's wrong you do the above and then X 100%.

 

[kelper]

ABV =(76.08 * (og-fg) / (1.775-og)) * (fg / 0.794)

https://www.brewersfriend.com/2011/06/16/alcohol-by-volume-calculator-updated/

 

[Racehunter]

So I assume, that if you are brewing say from a kit, with a stated ABV, using the SG and ABV, you can calculate the FG you are likely to see?