Are you sure this beer is the x ABV, I get asked.

[p_p]

I do get asked rutinely whether the beer I am serving has the ABV I am claiming.

I usually answer than clean fermentation produces less noticeable alcohols and that I am a very talented homebrewer. More often I just say shut up and keep drinking.

I am wondering though whether my friends are right and whether I am indeed miscalculating the ABV.

Having made sure my hydrometer is calibrated and any readings I do with a refractometer are in line, the attention turns to the fact that, for ABV calculations, I am taking in consideration the sugar added to prime bottles, which in my opinion is significant. Note I also take in consideration if the beer is diluted when adding finings, etc.

I did a bit of reading and found a post from 2009 in which opinions are divided although those bringing numbers to the table seem to agree there will an increase in ABV. I usually expect around .3% on a typical batch.

So, why, to the eyes of a few others, would my beers appear to have less alcohol than I believe them to have? (I judge by the buzz I get vs. the numbers in the brew sheet and I think ABV is fine)

What else can I do to check without having to invest in equipment, lab analysis, etc?

Thanks
pp

 

[FatDragon]

Are you trying to convince yourself or others? If you're trying to convince yourself, maybe send one of your beers off for a lab analysis if you can find a place to do it cheaply (maybe make a friend in a university chemistry lab) and see how it lines up with your numbers.

If you're trying to convince others, it's free beer. If they want to know the ABV with a greater level of certainty, they can run by the Tesco and pick up some Stella.

 

[p_p]

Good point. I am not trying to convince anybody ..
I am curious about it. I am using a spreadsheet I put together to formulate recipes and I am always in the quest to improve it and correct issues.

I did not mention in my post that I calculate ABV using an "alternate" formula I took from brewer's friends
ABV =(76.08 * (og-fg) / (1.775-og)) * (fg / 0.794)

I never really tried the conventional formula since they claimed the other is more accurate.
I got to their calculator and tried them both and it turns out that there is quite a difference. The alternate formula gives higher ABV than the traditional formula ..

Do you use software? What formula does it use?

 

[FatDragon]

Good point. I am not trying to convince anybody ..
I am curious about it. I am using a spreadsheet I put together to formulate recipes and I am always in the quest to improve it and correct issues.

I did not mention in my post that I calculate ABV using an "alternate" formula I took from brewer's friends
ABV =(76.08 * (og-fg) / (1.775-og)) * (fg / 0.794)

I never really tried the conventional formula since they claimed the other is more accurate.
I got to their calculator and tried them both and it turns out that there is quite a difference. The alternate formula gives higher ABV than the traditional formula ..

Do you use software? What formula does it use?

Under ~15p or 1.060 OG, your numbers should be pretty similar under either the standard formula (ABV = (og – fg) * 131.25) or the alternate formula. At higher ABV levels, they start to differ somewhat significantly, with the alternate formula reporting higher numbers. As you probably saw on Brewer's Friend when you got the formula, there is no 100% accurate formula for calculating ABV from gravity samples (otherwise there wouldn't be two alternate formulae, would there?), but both should be pretty close to the real thing unless you've got issues on the gravity measuring side.

In other words, as long as you trust your measurements, either formula will give you a close enough number to compare against commercial brews, even if you might be a couple tenths off.

 

[user 141939]

Yeah I thought at higher gravity levels that calculating abv became less accurate. I didn't realize there was an alternate formula so maybe one is more accurate than the other for higher abv.

I use to work in a lab that got beer samples from a brewery for higher abv beers for that very reason.

 

[user 141939]

That being said, no one ever asks me that. If they did in would just say it's close to that, but no, it's probably not 100% accurate.

 

[Homercidal]

Is it for all beer styles you get asked? I know that some styles seem to taste nowhere near as alcoholic as others. For instance, a Belgian Triple might seem much less high in alcohol than a DIPA.

It takes a bit of practice in finding the taste and sensation of alcohol for some people. Lots of people believe a dark beer is going to be higher in alcohol, although there is no reason to assume that.

 

[kh54s10]

I rarely even calculate the ABV. When I do I use Brewer's Friend's calculator. So if someone asks me the ABV, they only have once or twice, I say, "I don't know, it's somewhere near X ABV"
'

 

[mattdee1]

I use the "simple" ABV formula in my spreadsheet that is part of my brew journal.

Based on how the beers taste and how they "affect" me, I'd say the numbers I get seem very reasonable compared to vast experience with commercial products that I assume are quite tightly controlled.

Still, I harbor no illusions that the calculated figures I get are ever more accurate than +/- 0.5% on a good day.

Not that I care, because I usually just view ABV in 3 tiers--low, medium, and high. If somebody asks then they are almost certainly drinking one of my "lowest common denominator" beers, and I'll just say "it's right around 5%."

 

[AZCoolerBrewer]

I've been asked if I'm sure it is X ABV. I think most of the time they just can't figure out how you know what the ABV is since you don't have a lab. If you breifly explain how a hydrometer works, I think that answers the real question, which is, "Are you a wizard or are you ABV numbers just bullsquat?".