We can calculate the OG fairly accurately; surprise surprise there is an equation...
Mass of Extract in solution = Volume * SG * oP (oP) is Plato; roughly SG=(4*oP)/1000+1.
Your Volume is 23L, Your mass in solution is your dry 3Kg plus ~80% of the kit mass (1.7*0.8) 1.36kg
Using a spreadsheet and Goal Seek it pretty easy to work out that your OG was very close to 1.071
| V*SG*oP | | |
| v | SG | oP |
| 23 | 1.070812 | 17.70293 |
| M.E.= | 4.359995 | kg |
Call it 1.070
That won’t help you with the FG as we don’t know what you added, any Lactose for instance would be unfermentable, Sugar (Sucrose) is 100% fermentable and there is a huge range of answers between the two.
Similarly with yeast, some are more aggressive than others and will make more alcohol.
If we assumed you had a very fermentable wort and a good healthy yeast and got 80% apparent attenuation
(OG-FG/OG = 0.8) Better to do this in "Points" or oP, I get 3.54oP = ~1.014.
I doubt it got that low but the Maximum alcohol content would be around (OG-FG/7.5) or 71-14/7.5= 61/7.5 =8.133%.
That would be an absolute maximum and I would expect less.
If you still have a sample or some in a bottle or keg you could de-gas it and take a reading, should give you a pretty accurate answer.
Mark
