Measuring alcohol content

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Stigmond13

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I have been working on the assumption that starting gravity minus finished gravity divided by 7.36% gives me my alcohol per volume which is used in the UK but someone mentioned the other day that I was using the US calculation which is different. I d appreciate some clarification.

Thanks in advance.
 
Percent doesn't care about which country you are in. 7 out of 10 = 70% in liters, quarts, cubits, rods, chains, feet, miles...
 
I have been working on the assumption that starting gravity minus finished gravity divided by 7.36% gives me my alcohol per volume which is used in the UK but someone mentioned the other day that I was using the US calculation which is different. I d appreciate some clarification.

Thanks in advance.

That calculation is alcohol by weight. ABW. Alcohol by volume is a different measurement.
 
Thanks yooper, looks like my friend was correct, do you have the calculation to obtain alc by vol which is typically used in the uk?
 
Don't know if this is used in the UK, but will give you ABW.
ABW = ABV * 0.79336

ABV = (Orig_gravity - Final_gravity) * 131
 
The formula you have is from C J J Berry and does give ABV. It is close to eadavis80's formula, however yours estimates on the high side (1000/7.36 = 136). As such if one of the formulas had to be abw, it would be (og-fg)131.5, because abw is less than abv.

There are many formulas to approximate abv. They are derived in different ways, but most are no better than others. I happen to use Barry's formula. Most (beer) brewers use the other formula. I suspect that lower abv (beer) is better approximated by (og-fg)131.5 and higher abv (wine) by (og-fg)/7.36, but have no evidence for this claim other than the context in which each is typically found.

See also https://en.m.wikipedia.org/wiki/Alcohol_by_volume
 
If you have a smart phone or a tablet there a number of abv calculators apps. You put in your starting SG and your ending and it tells you your abv.
 
Anyone know how to figure the final alcohol content, ABV, when I added honey to a cider brew for bottling. So I have an initial reading (1.063), a reading following fermentation (1.002), a reading following addition of honey (1.030) and I will have a final reading once I crack a bottle. I know how to get the ABV following the initial process, but I assume I can't simply add the two resulting ABV numbers?
 
Anyone know how to figure the final alcohol content, ABV, when I added honey to a cider brew for bottling. So I have an initial reading (1.063), a reading following fermentation (1.002), a reading following addition of honey (1.030) and I will have a final reading once I crack a bottle. I know how to get the ABV following the initial process, but I assume I can't simply add the two resulting ABV numbers?

You added honey up to 1.030? Have you pasteurized it? That's definitely bottle bomb territory, and then some.
 
You added honey up to 1.030? Have you pasteurized it? That's definitely bottle bomb territory, and then some.

It's 4tblsp of raw honey in a gallon. Haven't had a problem with it before. Hopefully not jinxing myself :). I am using flip top bottles which are probably a little more pressure resistant than caps.
 
It's 4tblsp of raw honey in a gallon. Haven't had a problem with it before. Hopefully not jinxing myself :). I am using flip top bottles which are probably a little more pressure resistant than caps.

Something wrong with your figures, I think. Rule of thumb is that 1 lb of honey orsugar added to make a gallon of sugar water will result in a SG of 1.040. That means that an addition of 4 oz will increase the gravity by 10 points. You say your gravity rose by 28 points (from 1.002 to 1.030) which suggests a far larger addition than 4T of honey - closer to 12 oz, in fact - so either you are using a non standard tablespoon or the sample you took to measure the gravity was not adequately mixed...
 

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