Alcohol skews Brix readings. Get the true FG, °Plato and ABV — results update as you type.
Refractometer Correction
Brix → True FG, °Plato & ABV
Sean Terrill
Original Brix (OG)before fermentation
°Bx
Current Brix (FG)during / after ferment
°Bx
Refractometer Field of View
Original (OG)
correct
Current (uncorrected)
OG (from refractometer)
1.048412.0 °P
Uncorrected FG (wrong)
1.0217
Corrected Results
Corrected FG
1.0054
specific gravity
FG in Plato
1.4
degrees Plato
Est. ABV
5.64
% alcohol
(from corrected FG)
Alcohol bias corrected refractometer reading by -163 pts (lower than raw Brix → SG)
Why correction is needed
Refractometers measure light bending (refractive index). Before fermentation, only sugars affect the reading. Once alcohol is present it bends light too — making the reading lower than the true gravity. The Sean Terrill formula compensates for alcohol’s refractive index using your original Brix as a reference.