Author Topic: Estimated ABV not correct  (Read 2752 times)

Offline asparknz

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Estimated ABV not correct
« on: May 10, 2019, 02:08:35 AM »
Hi All

Im trying to wrap my head around this. The estimated alcohol in beer smith is off for me by about 2% i.e. if I have a recipe loaded with an o.g of 1.061 and an estimated f.g. of 1.000 Beersmith shows 10% Alc./vol However if I use the pct alcohol tab in the tools section it shows 8.1%

Any ideas?

Running Beersmith 3.0.8 on a mac

Cheers

Offline Oginme

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Re: Estimated ABV not correct
« Reply #1 on: May 10, 2019, 05:23:24 AM »
I have tested both the %ABV in a recipe and the stand alone tool and find that they correlate precisely (within round off error) to each other across a series of OG's from very low to very high.

Maybe there is something in your recipe that you are overlooking.  Are you looking at the estimated FG or the measured FG when you put the numbers into the recipe? 

If you export the recipe as a .bsmx file [highlight the file in the directory then click 'file' > 'export selected' > 'save as'] maybe we can see something from looking at the recipe directly.
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Offline brewfun

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Re: Estimated ABV not correct
« Reply #2 on: May 10, 2019, 06:44:38 AM »
I have a recipe loaded with an o.g of 1.061 and an estimated f.g. of 1.000 Beersmith shows 10% Alc./vol However if I use the pct alcohol tab in the tools section it shows 8.1%

I'm questioning your recipe numbers. It's pretty easy to miss a variable in a recipe and get a perplexing answer. The tool is showing you accurate information.

Something 100% fermentable at 1.061, like honey or juice, has enough sugar for 8.5%. For 10%, you need to be in the neighborhood of 1.072.

The final gravity of something 100% fermentable, will be less than 1.000 because alcohol is lighter than water.

The default maximum abv is 10%. The yeast you choose can change that if its tolerance is higher or lower. You can manually change the yeast to a higher tolerance, but it doesn't mean the yeast will achieve it.

Beer Appreciation is the space between pints.

Offline asparknz

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Re: Estimated ABV not correct
« Reply #3 on: May 12, 2019, 02:46:14 AM »
Thank for the reply.

The recipe is simple, its a rum wash so just some turbinado sugar, although Ive substituted for dextrose to see if it made a difference which it did not. Your right the estimated f.g. is 0.985.

Recipe attached, let me know what Im missing?

Cheers


Offline brewfun

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Re: Estimated ABV not correct
« Reply #4 on: May 12, 2019, 05:20:16 PM »
Your OP said:

Im trying to wrap my head around this. The estimated alcohol in beer smith is off for me by about 2% i.e. if I have a recipe loaded with an o.g of 1.061 and an estimated f.g. of 1.000 Beersmith shows 10% Alc./vol However if I use the pct alcohol tab in the tools section it shows 8.1%

Your recipe calculations show:
OG: 1.064
FG: 0.985
Est ABV%: 10.4

The user defined fields (everything labeled "Measured" or "Meas") call for the gravities and abv% in your OP. This is where the error lies. Teh measured gravities are closer together than what BeerSmith predicts, so the resulting ABV% is lower and matches your OP.

However, your volumes are far different than the equipment profile, The recipe is set as All-Grain and the equipment is for Cider, so, I'm a bit confused about what's happened. ...Or you just haven't made the recipe, yet.

If you haven't made the recipe, then all's good. Whatever the situation IRL, BeerSmith is predicting correctly and it matches the ABV tool.


Beer Appreciation is the space between pints.

Offline asparknz

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Re: Estimated ABV not correct
« Reply #5 on: May 14, 2019, 06:50:15 PM »
At a guess I would say I was looking at the predicted alc./vol based on an f.g of 0.989 and then referencing the pct alcohol tool by using a f.g. of 1.000 This is why I was getting different values, it appears I confused and confounded myself by having different finishing gravities

Estimated ABV is correct and I appreciate the help