I brewed Denny’s Wry Smile about a month ago, and it’s been sitting in primary ever since (waiting for a keg to open up, which just happened last night). I took a sample for tasting & gravity measurement purposes, and I have some questions.

OG: 19.3% Brix

FG: 10.3% Brix

Using Sean Terrill’s calculator, this gives me something like OG 1.077 and FG 1.018, which would give me an apparent attenuation of ~75% (actual attenuation lower at ~62%).

Using the “standard” calculator (e.g., Beersmith), I get higher OGs (+0.004) and lower FGs (-0.003), which bumps up the attenuation +5-7%.

My question is twofold:

(1) Is this a normal level of attenuation for Denny’s Fav50 yeast (and/or the usual attenuation, period), all else held constant?

(2) Is the general consensus that Sean’s refractometer calculator (cubic equation?) should be the standard?