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Brix to Specific Gravity Converter (and Plato, Baumé, Oechsle)

Convert °Brix or °Plato to specific gravity and back with the ASBC polynomial, the Lincoln (BYO) equation or the 4-points rule — plus Oechsle, Baumé, sugar in g/L and potential alcohol. Correct a refractometer reading on wort with your wort correction factor, or work out that factor from a hydrometer reading.

Convert from

Value

Wort correction factor

Hydrometer reading of the same wort (SG)

Brix ↔ SG formula

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How it works

ASBC: °P = −616.868 + 1111.14·SG − 630.272·SG² + 135.997·SG³ (solved numerically for Brix → SG); Lincoln (BYO): SG = 1 + °Bx ÷ (258.6 − (°Bx ÷ 258.2) × 227.1); rule of thumb: SG ≈ 1 + °Bx × 4 ÷ 1000; refractometer: °Bx corrected = reading ÷ WCF, WCF = reading ÷ hydrometer °Plato; °Oe = (SG − 1) × 1000; °Bé = 145 − 145 ÷ SG; sugar g/L = °Bx × SG × 10

Brewers, winemakers and juice producers all measure the same thing — dissolved sugar — on different scales. Brix and Plato are both grams of sucrose per 100 g of solution and differ only in the fifth decimal, so they are used interchangeably; specific gravity is density relative to water and is what a hydrometer reads directly; Oechsle (German and Swiss winemaking) is simply the gravity points; Baumé (French and Australian winemaking) is a density scale that happens to approximate the potential alcohol of a dry wine. Brix and gravity are not exactly proportional, so the conversion needs a curve. The ASBC polynomial is the brewing-industry fit to the sucrose tables; the Lincoln equation used by Brew Your Own and many homebrew apps agrees with it to 0.0001 up to about 25 °Brix; and the 4-points rule (1 °Brix ≈ 4 gravity points) is a handy mental shortcut that reads low on strong worts and musts — pick any of the three and the comparison table shows all of them side by side. A refractometer measures how much light bends rather than density, and wort’s mix of sugars bends light a little more than pure sucrose, so most refractometers read about 4% high on wort. Divide the reading by your wort correction factor (1.04 if you have not measured yours), or let the calculator work the factor out from a refractometer and a hydrometer reading of the same wort. Potential alcohol depends on how completely the sugar ferments — wine yeasts leave almost nothing, beer usually finishes around 1.010.

Worked example

22 °Brix grape must: SG 1.0920 by both the ASBC polynomial and the Lincoln equation (the 4-points rule says 1.088), 92 °Oe, 12.2 °Bé, about 240 g/L of sugar — potential alcohol 12–13% if fermented dry. A refractometer showing 13.0 °Brix on wort, with the usual 1.04 correction factor, means 13.0 ÷ 1.04 = 12.5 °Brix, or SG 1.050. If your hydrometer reads 1.050 on a wort the refractometer calls 13.0 °Brix, your factor is 13.0 ÷ 12.39 = 1.049.

Sources: Brix — sucrose and specific gravity tables (Wikipedia) · Brewfather — Refractometer tool documentation · Brewer’s Friend — determining your refractometer’s wort correction factor

Frequently asked questions

Are Brix and Plato really the same?

For practical purposes yes; they were calibrated on slightly different sucrose tables and differ by less than 0.05° in the brewing range.

Which Brix to SG formula should I use?

For wort, must and juice up to about 25 °Brix, the ASBC polynomial and the Lincoln equation give the same gravity to four decimals, so either is fine. The 4-points rule is close below about 12 °Brix and drifts low above it — 22 °Brix gives 1.088 instead of 1.092.

What is a wort correction factor?

A refractometer is calibrated on sucrose, but wort’s mix of maltose and other sugars reads slightly high, typically by 2–6%. The factor (1.04 by default) corrects for that: corrected °Brix = reading ÷ factor. It applies only before fermentation; alcohol changes the reading in a different way.

How do I measure my own correction factor?

Take a sample of unfermented wort, read it with the refractometer and with a temperature-corrected hydrometer, and choose “Find my refractometer’s wort correction factor”. The factor is the refractometer °Brix divided by the hydrometer’s °Plato. Repeat on a few worts and average the results.

Why is Baumé roughly equal to alcohol?

Coincidence of scale: 1 °Bé ≈ 1.8 °Brix, and 1.8 °Brix of sugar ferments to about 1% alcohol, so a 12 °Bé must makes about 12% wine.

Related calculators

Refractometer Correction Calculator (Fermenting Beer)

Correct a refractometer Brix reading taken during or after fermentation for the alcohol present. Start from the original Brix or a hydrometer OG, choose the Terrill cubic or linear correction, and get the true final gravity, ABV (standard and high-gravity formulas), ABW, apparent and real attenuation, your wort correction factor and a reading-by-reading table and chart.

Hydrometer Temperature Correction Calculator

Correct a specific gravity reading taken at any temperature to the hydrometer’s calibration temperature (15.6 °C / 60 °F or 20 °C) — for accurate OG, FG and ABV in brewing and winemaking.

Potential Alcohol Calculator (Wine, Cider, Mead, Beer)

Potential ABV from the starting gravity, Brix or Baumé of a must, juice or wort — fermented dry or to a chosen final gravity — by the standard, alternative, Hall, Balling and winemaker formulas, with hydrometer temperature correction, refractometer final readings, sugar added later, attenuation, calories and an ABV-by-final-gravity table.

Beer ABV Calculator (OG/FG)

Calculate the alcohol by volume, apparent attenuation and gravity drop of a homebrew from its original and final gravity.

Chaptalization Calculator (Sugar to Raise Brix / Potential Alcohol)

How much sugar to add to a must, juice or mead to reach a target Brix, specific gravity or potential alcohol, by exact mass balance. Table sugar, dextrose, honey, grape concentrate or your own syrup, in grams, kilograms, pounds and cups, with the new volume, a staged-addition table, and the water needed if you want to lower the Brix instead.

This calculator is for educational purposes. Double-check important results before acting on them.