SG to Brix Converter

Specific gravity measures density against water, with water itself defined as exactly 1.000. Brix expresses the same dissolved sugar as a percentage by weight, as if the solution were pure sucrose in water. The cubic formula above is the accepted relation used in brewing and winemaking, developed to match real sucrose solution density data rather than a simplified linear approximation.

A cubic formula is needed because the relationship between dissolved sugar and solution density isn't perfectly straight-line. At low concentrations the two scales track each other closely, but the curve bends slightly as concentration rises, which a single linear factor can't capture accurately across the full brewing and winemaking range.

After fermentation begins the dissolved solids are no longer pure sugar, so a converted Brix figure becomes an approximation. Ethanol is less dense than water, so a must partway through fermentation reads a lower apparent Brix than the sugar actually remaining, which is exactly why brewers use separate apparent and real extract figures rather than relying on a direct conversion mid-ferment.

Hydrometers most commonly read in specific gravity, while refractometers are commonly scaled in Brix, so the practical choice often comes down to which instrument is in your hand. Winemakers working from European tradition also frequently think in Brix or the closely related Oechsle and Baume scales, while many English-language homebrewing resources default to SG.

Whichever scale you track a batch in, staying on that one scale from original reading through to final reading avoids the small rounding differences that creep in from converting back and forth at each step. If you need to compare a reading against a recipe written in the other scale, converting once at the start of the batch is cleaner than converting every reading as you go.