Brix, Plato, specific gravity and Baumé, plus the two corrections that make a real reading usable — for wort, must, cane juice, sap and kombucha.
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12 Brix (°Bx)
1.0484 specific gravity
12.00 °P · 6.69 °Bé · about 6.3% potential alcohol if it ferments dry
The same measurement on every scale
Four scales, one solution — none of these conversions is exact
Scale
Value
Where it is used
Brix (°Bx)
12.00
Wine, juice, sugarcane, maple, kombucha
Plato (°P)
12.00
Brewing, worldwide
Specific gravity
1.0484
Brewing and winemaking, especially in the UK and US
Baumé (°Bé)
6.69
Winemaking in Australia and France, sugar refining
These are empirical fits, not definitions. Converting Plato to gravity and back does not return exactly what you started with, because the two directions use two different published polynomials — which is why two calculators can disagree in the third decimal and both be correct. Brix and Plato come from separate tables too, and agree to better than 0.05 °P below 20, which is why the industry treats them as interchangeable.
Refractometer, after fermentation started
Original gravity1.0464no alcohol yet, so no correction needed
Final gravity — Terrill’s cubic1.01304.39% ABV
Final gravity — the linear fit1.01121.8 points from the other one
If you read it uncorrected1.02472.85% ABV — 1.54 points too low
A refractometer measures how much light bends, and ethanol bends light far less than sugar water does. The moment fermentation begins, the reading is no longer a sugar measurement, and reading it as one puts the final gravity 12 points too high. The correction needs the original reading as well, because there is no way to tell how much alcohol is in the sample from the current reading alone.
Both published corrections are shown because they disagree, and choosing between them is a judgement rather than arithmetic. The wort correction factor belongs to your particular instrument — refractometers are calibrated against sucrose and read high on wort, usually by 2 to 6 per cent. If you have calibrated yours against a hydrometer, use that figure rather than the default.
Hydrometer, read warm
As read1.0500at 86 °F (30.0 °C)
Corrected to 68 °F1.05262.6 points
A hydrometer floats in a liquid whose density changes with temperature, and it is calibrated for one — usually 20 °C. A warm sample is less dense, so the hydrometer sinks further and reads low. The relationship is a cubic rather than a straight line, so the common rule of thumb of one point per ten degrees drifts at the extremes.
Something to measure against
Where common measurements sit on the scale
Solution
Brix
Gravity
Note
Water
0
1.0000
Specific gravity 1.000 by definition.
Light lager wort
10
1.0400
About 1.040. Ferments out to roughly 4% ABV.
Ripe wine grapes
22
1.0920
About 1.092. Ferments out near 12–13% ABV.
Sugarcane juice at harvest
18
1.0741
The figure Indian and Brazilian mills are paid on.
Maple sap
2
1.0078
Boiled down roughly forty-fold to reach syrup.
Maple syrup, finished
66
—
Above the range of most refractometers and of this converter.
Two rows sit outside what a converter should be trusted for. Finished maple syrup at 66 °Bx is beyond the range of most handheld refractometers and beyond the range these polynomials were fitted over, and sap at 2 °Bx is where the fortyfold boil starts. The middle of the table — wort, must and cane juice — is where the fits are at their best.
What this converter covers
All four sugar scales at once, refractometer correction from both published fits, hydrometer temperature correction, and two alcohol estimates.
Brix, Plato, specific gravity and Baumé, in any direction
Refractometer readings corrected for the alcohol already present
Both published corrections, side by side, because they disagree
The wort correction factor as an instrument-specific input
Hydrometer readings corrected for sample temperature
Fits, not definitions Refractometer correction Temperature correction Brix · Plato · SG · Baumé
12 °Bx is SG 1.0484 · a refractometer reading 6.5 °Bx after starting at 12 is 1.013, not 1.025
Educational estimate
Planning support from the values you enter — not professional advice.
Four scales, one measurement
Brix, Plato, specific gravity and Baumé all answer the same question — how much dissolved sugar is in this liquid — and each belongs to a different trade.
Who uses which, and why
Scale
Reads
Used by
Brix (°Bx)
Grams of sucrose per 100 g
Wine, juice, sugarcane, maple, kombucha
Plato (°P)
The same idea, a different table
Brewing, nearly everywhere
Specific gravity
Density against water
UK and US brewing and winemaking
Baumé (°Bé)
Roughly Brix ÷ 1.8
Australian and French winemaking, sugar refining
Brix and Plato come from separate historical tables and are not formally the same scale, but below 20 they agree to better than 0.05, which is well inside what any handheld instrument can resolve. Treating them as interchangeable is the industry convention and it is a safe one.
Baumé earns its place through a coincidence that turned out to be useful: one degree is close to one per cent potential alcohol, so an Australian winemaker reading 12.5 °Bé is reading roughly the wine that will result. That is why the scale survived in winemaking long after it faded elsewhere.
Nothing here is exact
Every conversion on this page is a polynomial fitted to measured sugar solutions. None of them is a definition, and that has a consequence worth stating plainly.
Convert 10 °P to specific gravity and back, and you do not get 10. You get about 9.99, because the two directions use two different published fits — the reciprocal formula going one way and a cubic coming back.
This is why two calculators can disagree in the third decimal place and both be correct. They have chosen different fits from a literature that contains several, and the differences are smaller than the measurement error of the instrument either way.
It also sets the right expectation for precision. A gravity quoted to four decimal places suggests an accuracy that neither the fit nor a floating glass hydrometer possesses. One or two points of gravity is the honest resolution, and rounding past that is arithmetic rather than measurement.
And the fits were made on sugar solutions. Wort and must are not: they carry acids, proteins, salts and unfermentable sugars, all of which move density and refractive index in ways a sucrose table never saw.
When the refractometer stops working
This is the failure that matters most, because the instrument gives no sign of it.
A refractometer measures how much a drop of liquid bends light, and converts that to Brix using a sucrose table. It is fast, needs two drops instead of a jar, and is genuinely excellent — right up until fermentation starts.
Ethanol has a much lower refractive index than sugar water. Once there is alcohol in the sample, the reading is no longer measuring sugar at all: it is measuring a mixture, and reading it against a sucrose table gives a number that is far too high for the sugar actually left.
Take a wort that started at 12 °Bx. Fermented out, the refractometer reads about 6.5. Read as sugar, that implies a final gravity near 1.025 and a beer of about 2.9% — a stuck fermentation. Corrected for the alcohol, the real final gravity is near 1.013 and the beer is about 4.4%. Nothing is stuck; the instrument was.
The correction needs both readings, and that is not a limitation of this implementation. There is genuinely no way to tell how much alcohol is in the sample from the current reading alone — so the calculator above returns nothing without an original reading, rather than guessing at one.
Two corrections that disagree
Having established that a correction is needed, there is a second question most tools answer silently: which correction.
Two families are in common use. An older linear-family fit has been circulating in brewing software for decades, and a later cubic fit was derived from a larger set of paired refractometer and hydrometer measurements. They do not agree.
On the worked example above they differ by roughly two points of gravity, which is about a quarter of a per cent of alcohol. That is small enough to ignore for a home batch and large enough to matter if you are recording attenuation across batches, or deciding whether a fermentation has finished.
So both are shown. Choosing between them is a judgement about which dataset resembles your beer, and a calculator that picked one without saying so would be making that judgement on your behalf and hiding it.
A third input belongs to you rather than to either fit: the wort correction factor. Refractometers are calibrated against sucrose and read high on wort, typically by 2 to 6 per cent. The usual default is 1.04, but the right value is the one you establish by comparing your own refractometer against a hydrometer on the same sample.
Temperature, and the rule of thumb
Hydrometers have their own version of the same problem, and it is much better known — which is why it is worth being precise about where the familiar shortcut breaks.
A hydrometer floats at a depth set by the density of the liquid, and liquids expand when warm. A warm sample is less dense, the hydrometer sinks further, and the reading comes out low. Every hydrometer is therefore calibrated for one temperature, usually 20 °C, and stamped with it.
The rule of thumb is one gravity point per ten degrees Fahrenheit above calibration. Near calibration temperature that is close enough. At 86 °F it is already under-correcting — the true correction is nearer two and a half points — and it drifts further as the sample gets hotter, because the density of water is a cubic in temperature rather than a straight line.
Which matters most when you are least likely to be careful: taking a gravity reading on hot wort straight out of the kettle. A reading at 100 °F corrected by the rule of thumb is still several points low, and several points is the difference between an original gravity you record and one you actually had.
Refractometers are largely spared this, since most are automatically temperature compensated over an ordinary working range — which is exactly why they are convenient before fermentation, and exactly why the alcohol problem above catches people out afterwards.
Related calculators
Other density, concentration and kitchen tools:
Alcohol UnitsAny drink into grams of pure alcohol and into five national standards at once — because a UK unit and a US standard drink differ by 77%.
Densitykg/m³, lb/ft³, lb/in³ and lb/gal, with specific gravity against any water reference and the API scale that runs backwards.
TemperatureCelsius, Fahrenheit, kelvin and Rankine — and temperature CHANGES, which convert differently from readings.
CookingCups, spoons and sticks to grams for 16 ingredients — with all five cups, the 20 mL Australian tablespoon, and flour as a range.
PPMppm to percent, mg/L and µg/m³ — asking which liquid or which gas, because without that the conversion has no answer.
Volume to WeightGallons to pounds, cubic yards to tons, litres to kilograms — by substance, with an honest range rather than one invented number.
The sugar scales themselves come from the international sucrose tables; the winemaking practice and the Baumé scale from a research body that publishes for its own industry; and the regulatory reference is here to make the point that a gravity-derived alcohol figure is an estimate, not a measurement.
Winemaking resources — measuring sugar and BauméThe Australian Wine Research Institute · verified 2026-09-08 · The Baumé scale as used in Australian winemaking, where one degree is close to one per cent potential alcohol, and the practice of measuring must with a refractometer before fermentation and a hydrometer after
Wine — regulated commoditiesAlcohol and Tobacco Tax and Trade Bureau, US Department of the Treasury · verified 2026-09-08 · That alcohol content for regulatory purposes is determined by defined laboratory methods rather than by arithmetic on gravity readings, which is the reason this page presents two alcohol estimates rather than one number
Conversion note
These conversions are empirical fits to sugar solutions, and real wort, must, juice and sap are not sugar solutions — they contain acids, salts, proteins and unfermentable sugars that shift both density and refractive index. Treat every figure here as good to a point or two of gravity rather than as an analytical result. Alcohol figures derived from gravity are estimates: two published formulas are shown precisely because they disagree, and neither is a laboratory method. Anyone determining alcohol content for a label, for duty, or for any regulatory purpose must use the method their jurisdiction specifies, which will be distillation or an instrumental method rather than arithmetic on a hydrometer. The refractometer correction assumes a normally fermenting sample and a correctly calibrated instrument; the wort correction factor varies between instruments and should be established against a hydrometer rather than taken from a default. Readings outside roughly 0 to 45 on the sugar scales, including finished syrups, fall outside the range these polynomials were fitted over and are not returned.
Published the Brix to SG Converter: Brix, Plato, specific gravity and Baume in any direction, for wort, must, cane juice, sap and kombucha.
States that none of these conversions is exact. They are empirical polynomials fitted to sucrose solutions, so converting 10 degrees Plato to gravity and back returns about 9.99 -- which is why two calculators can disagree in the third decimal and both be right.
Records that Brix and Plato come from separate historical tables and agree to better than 0.05 below 20, so treating them as interchangeable is a convention rather than an identity.
Corrects a refractometer reading taken after fermentation has begun, which is the failure the page exists for: ethanol bends light far less than sugar water does, so the instrument silently stops measuring sugar.
Shows the size of the error rather than only the fix. A wort started at 12 Brix and read at 6.5 implies a final gravity near 1.025 and 2.9 per cent alcohol if read raw, against 1.013 and 4.4 per cent once corrected -- the difference between a finished beer and an apparently stuck one.
Refuses to correct without the ORIGINAL reading, because there is genuinely no way to infer how much alcohol is present from the current reading alone.
Returns BOTH published corrections side by side, the older linear-family fit and the later cubic, because they differ by about two gravity points and choosing between them is a judgement that belongs to the brewer.
Treats the wort correction factor as an instrument-specific input rather than a constant, since refractometers are calibrated on sucrose and read high on wort by 2 to 6 per cent.
Corrects hydrometer readings for sample temperature with the cubic relationship rather than the one-point-per-ten-degrees rule of thumb, and shows where that rule starts under-correcting.
Verified by 53 automated cases, asserting the polynomials against the polynomials themselves rather than against copied decimals, that the two fits round-trip to about a hundredth of a degree and no better, that an uncorrected refractometer reading overstates final gravity by more than ten points and understates alcohol by more than a point, and that a current reading above the original is refused.
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