formula for abv from refractometer readings

[bobukbrewer]

I have two formulas, one is =IF(F7=0, (0.01/0.8192)*((C7/$E$3)-(0.1808*(C7/$E$3) + 0.8192*(668.72*H7 - 463.37 - 205.347*H7^2)))/(2.0665 - 0.010665*(C7/$E$3)), (0.01/0.8192)*((C7/$E$3)-(0.1808*(C7/$E$3) + 0.8192*(668.72*F7 - 463.37 - 205.347*F7^2)))/(2.0665 - 0.010665*(C7/$E$3))) where C7 and D7 are OG and FG in BRIX, this gives 2.52 abv for my last brew with OG 9 and FG 5.9

the other formula is =B36*B37/0.791 giving 2.74 abv with B35 being =((C7/$E$3)/(258.6-(((C7/$E$3)/258.2)*227.1))+1)

e3 is wort correction factor 1.04
b36 is =-0.002349*C7+0.006276*D7+1
b37 is abw =0.67062*C7-0.66091*D7

which do you consider is most accurate
(I wish to use refractometer only so no plugs for hydrometers please

 

[Bigcol49]

Hi!
The problem is findingthe wort corection factor oyour refractometer.

 

[bobukbrewer]

I am happy with 1.04