Refractometer Correction

Convert refractometer Brix readings to gravity and estimate FG and ABV in fermenting beer, including correction factor.

Refractometer reading

°Bx

The Brix (WRI) value your refractometer shows.

Wort correction factor

Most refractometers read slightly high on wort — 1.04 is the Brewfather default. Calibrate below for your unit.

Estimated gravity

1.048

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How this calculator works

A refractometer is straightforward before fermentation, but alcohol changes how light bends through the sample after fermentation starts.

In wort mode, the tool converts a corrected Brix reading into gravity.

In fermenting-beer mode, it uses the original gravity, current Brix reading and your correction factor to estimate final gravity and alcohol.

Calibrate your correction factor by comparing the same unfermented wort with both a refractometer and a hydrometer.
Treat fermenting-beer refractometer results as estimates, especially before packaging.