Working Backwards

[SiHoltye]

Just measured the SG of bottled London Pride

SG (FG) = 1.011

ABV is stated as 4.7%

Using an alcohol calculator the OG should have been 1.047 to achieve 4.7%ABV finishing at 1.011

Now the Maths...11/47=0.234...so attenuation achieved was 77%ish

WLP002 or WY1968 alledgedly is 'Fullers strain', do people get this level of attenuation out the liquid yeasts? Haven't checked my numbers but over half a dozen attempts don't think I've passed 74%, more usually 72%

[mysterio]

Higher pitching rates, ferment temps or fermenter geometry might account for it. I tend to get around 75% attenuation, i've only measured with this yeast twice though.

Also the yeast they'll be using will be in peak health, the tubes we get from WL certainly aren't. It's possible that after a few re-pitches the yeast will get used to their environment and ferment a little more.

[piet_v]

Do they use sugar ?

[coatesg]

ABV is stated as 4.7%

Using an alcohol calculator the OG should have been 1.047 to achieve 4.7%ABV finishing at 1.011

Remember the bottle ABV won't necessarily be accurate either - it could be a bit off - within 0.5% I think. If you've got a refractometer, I think you can work it backwards using a reading from that and the hydro: clicky.