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Brix to Specific Gravity Calculator

Specific gravity from a Brix reading, as used for wine musts and brewing worts.

How it is calculated

You enter the sugar content in degrees Brix (°Bx), the grams of sucrose per 100 g of solution, and the tool returns specific gravity (SG), the density relative to water, which is 1.0000. It uses SG = 1 + Brix ÷ (258.6 − (Brix ÷ 258.2) × 227.1) and shows four decimals. A value of 0 °Bx gives 1.0000, and negative Brix returns nothing. The formula is a fit for a pure sucrose solution, so it matches juice, must and wort only approximately because they also contain other dissolved solids. It converts in one direction only, from Brix to SG, and it does not correct for temperature or for alcohol.

Worked example

A refractometer reads 12 °Bx on grape must. First, 12 ÷ 258.2 = 0.04647, and multiplying by 227.1 gives 10.5546. Subtract from 258.6: 258.6 − 10.5546 = 248.0454. Divide Brix by that: 12 ÷ 248.0454 = 0.04838. Add 1 to get an SG of 1.0484. For comparison, 25 °Bx gives 1.1057, showing that SG rises a bit faster than in a straight line as sugar increases.

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Common mistakes

  • Using a refractometer reading taken after fermentation has started. Alcohol changes the reading, so the Brix is no longer a sugar value and this formula would give a misleading SG.
  • Typing the SG or the Plato-style value as Brix. Brix is in degrees, such as 12, not 1.048.
  • Ignoring temperature. Refractometers and hydrometers are calibrated at a set temperature, so a hot sample gives a skewed reading before it ever reaches this tool.
  • Expecting the output to match a hydrometer exactly. Must and wort contain more than sucrose, so a hydrometer reading can differ by a few thousandths.

About this calculator

Degrees Brix (°Bx) measures the sugar content of a liquid as grams of sucrose per 100 grams of solution, while specific gravity (SG) compares the liquid's density to that of water. The two are linked by an empirical formula — commonly approximated as SG = 1 + (Brix / (258.6 − ((Brix / 258.2) × 227.1))) — since dissolved sugar increases both the Brix reading and the density of the solution together.

Winemakers and brewers use this conversion to estimate the potential alcohol a must or wort will produce during fermentation, reading Brix from a refractometer and converting to the specific gravity figure that most fermentation and alcohol-yield calculations are built around.

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  • Editorial team

    Use this on unfermented juice, must or wort only, and take the reading at the temperature your refractometer is calibrated for. A 12 degree Brix sample gives 1.0484 here, a figure you can compare with a hydrometer taken at the same time to see how far your liquid departs from pure sugar water. Brewers who think in degrees Plato can use a Plato figure as a close approximation. Which beverage are you measuring, and how well does the result match your hydrometer?

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