Mead Lover's Digest #1412 Wed 11 March 2009

Forum for Discussion of Mead Making and Consuming
Dick Dunn, Digest Janitor


ABV calculation? ("Louis LeBlanc")

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Subject: ABV calculation?
From: "Louis LeBlanc" <>
Date: Fri, 6 Mar 2009 01:02:19 -0500 (EST)

Cheers everyone,

I'm sorry in advance for the long question, but I've done a lot of up front
work to try to answer this question myself, and it's starting to look like
*nobody* really knows the answer here.

This evening, I racked a 5 gallon batch of maple mead from the primary into a
carboy. This batch started with 6 lbs medium amber grade A maple syrup, 2 1/2
lbs buckwheat honey, 6 1/2 lbs light clover honey.

The OG was exactly 1.120, which was my target, so I was pretty happy to have
it land right there. This was taken after warming (no more than 130 degrees
F) and mixing, then giving the must a night to "set". I then mixed it well
(not worrying about aeration yet) and checked the gravity before pitching and

This evening marked 15 days of activity, and 2 days after the real slowdown.
I tested the gravity and found it to be exactly 1.010, which gives a gravity
variance of -0.110. Now to figure out ABV.

There are a lot of calculators online, including rooftop, gotmead, and a half
dozen others – all impressive enough in their own right. But out of about 6
different methods, no two seem to agree.

The question is how do I *really* calculate ABV from the gravity variance?
According to Schramm, 1 lb of honey gives a gravity increase of 0.008 to a 5
gallon batch. I've found this to be pretty accurate. He also says that that
1 lb honey will give a potential of 1% in alcohol. By that formula, I've got
13.75% ABV.

My hydrometer shows the 1.120 SG point is almost exactly 16% potential, where
1.010 is almost exactly 1.25% potential, giving 14.75% ABV.

If I run through Charlie Papazian's formula, I multiply the variance by 105
for 11.55% ABW, then multiplying that by 1.25 for 14.43% ABV. I seem to
remember somewhere else said multiply by 131 to get ABV, where Charlie's
formula is actually multiplying by 131.25. That's close, anyway – and is
actually very close to the calculator at In fact, this is the only
two methods I've found that even remotely agree.

According to the online calculators, I've got somewhere between 14.44% and
16%. The one on gotmead suggests I have 15.37% – arrived at by subtracting
the potential for 1.010 from that for 1.120.

I've also found elsewhere (can't remember where just now) that it is actually
0.00753 in gravity variance for a 5 gallon batch that gives 1% ABV, which
suggests just over 14.6% ABV.

So, now the kicker: The yeast I've used here is Lalvin D-47. The info sheet
from Lalvin says this yeast has a typical ABV tolerance of "up to 14%" (though
some folks claim it is a 15% yeast). Now I realize this is only "typical" and
it is entirely possible to push the envelope here, but this only just slowed
down 2 days ago, and was still showing a little activity. Surely it should
just be approaching it's tolerance?

I'm confused: do I have 13.75%? 16%? Something in between? What's the "real"
magic number to use for a 5 gallon batch? And who's the authority on this?

I'm aware this is far less important than actually enjoying the stuff (and I
*was* surprised how good it tastes), but hey, I'm a numbers guy, so …

Thank you all


End of Mead Lover's Digest #1412