[a10t2]

Consider that if it were truly 1.074 and pretend your FG was 1.020...this would be a 7.09% beer. If the OG truly was 1.072, you'd end up with 6.83% ABV.

Except that we aren't measuring the ABV, so all you could honestly say in either case is that it's probably between 6.5% and 7.5%.

[flbrewer]

What am I missing? Is the FG vs OG not an exact measurement of ABV?

[a10t2]

What am I missing? Is the FG vs OG not an exact measurement of ABV?

Not even close. It's an accurate measurement of how much dissolved extract changed during fermentation. Anything beyond that requires making assumptions about the composition of those sugars, and how much ethanol was produced as opposed to CO2, yeast biomass, etc.

[flbrewer]

Ok, call it 1-10%

[Wort-H.O.G.]

What am I missing? Is the FG vs OG not an exact measurement of ABV?

Not even close. It's an accurate measurement of how much dissolved extract changed during fermentation. Anything beyond that requires making assumptions about the composition of those sugars, and how much ethanol was produced as opposed to CO2, yeast biomass, etc.

All things considered, the abv calcs are estimates. What's your experience with the etimatates vs. actual Sean?


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[a10t2]

All things considered, the abv calcs are estimates. What's your experience with the etimatates vs. actual Sean?

In the batches I've actually had tested, which is 200 or so, but all in the same brewery, the estimate 0.525(OG-FG) was always within ±1% and almost always within the ±0.3% the TTB requires for labeling.