CalculateFermentation correction
Refractometer Correction Calculator
Free refractometer correction calculator. Convert original and final Brix readings into a corrected final gravity and ABV using the wort correction factor.
Correct a refractometer Brix reading into a true final gravity once alcohol is present.
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How the Refractometer Correction Calculator works
Refractometers read sugar content in °Brix and are handy for quick gravity checks. Once fermentation produces alcohol, however, the reading is skewed and must be corrected to recover the true final gravity.
This calculator applies Terrill's cubic correction using a wort correction factor (WCF). Enter your original and final Brix readings to get the corrected final gravity, original gravity, and estimated ABV.
Frequently asked questions
- Why correct a refractometer reading?
- Alcohol changes how light refracts, so a refractometer over-reads final gravity. A correction formula recovers the true value.
- What is the wort correction factor (WCF)?
- Refractometers typically read about 4% high on wort versus a hydrometer, so a WCF of ~1.04 is used. Calibrate against a hydrometer for accuracy.
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