Brix, Plato, and specific gravity are three related ways to describe a liquid’s sugar content and density. Brix is commonly used for wine and juice, Plato is standard in beer brewing, and specific gravity is the density reading most familiar to homebrewers. Each offers a different way to express a wort or juice’s sugar content and density, so a value entered in any one can be converted to equivalent readings in the other two. Because Brix and Plato use different fitted relationships with specific gravity, their converted values are close but not always identical.
Brix, Plato & Specific Gravity Converter
Enter a value in °Brix, °Plato, or SG to instantly see the other two — Free, no Sign-up.
Validated range: 0–40 °Bx / 0–39.9459 °P (SG 1.0000–1.1790). Outside it, values are extrapolated from fitted curves and may be inaccurate. For estimation only — not intended for commercial production or trade.
How Brix, Plato, and Specific Gravity Relate
Brix to SG Formula
There is no single multiplication that turns Brix into specific gravity, because the two scales measure different things: Brix is a percentage by mass, while SG is a ratio of densities. The conversion below is the one used by Brew Your Own magazine and by most brewing calculators, including this one.
SG = °Bx ÷ (258.6 − (°Bx ÷ 258.2) × 227.1) + 1
What Each Part Means
- °Bx — degrees Brix: grams of dissolved sugar per 100 g of solution. A 20 °Bx solution is 20% sugar by mass.
- SG — specific gravity: the density of the solution relative to water, measured at 20 °C/20 °C. Pure water is 1.000.
- 258.6, 258.2, 227.1 — empirical constants. They do not represent a physical quantity; they are the best fit to laboratory measurements of sucrose solutions.
Worked Example: 22 °Bx to SG
- 22.0 ÷ 258.2 = 0.0852
- 0.0852 × 227.1 = 19.35
- 258.6 − 19.35 = 239.25
- 22.0 ÷ 239.25 = 0.09195
- 0.09195 + 1 = 1.0920 SG
A 22 °Bx solution — a strong wort, or a sweet dessert-wine must — comes out at SG 1.0920, which works out to roughly 12.9% potential ABV if it ferments to dryness.
SG to Brix and Plato Formula
Going the other way, from a hydrometer reading to Brix, uses a cubic fit to the NBS reference table of sucrose solutions:
°Bx = 182.46007·SG3 − 775.68212·SG2 + 1262.7794·SG − 669.56218
Plato uses a cubic fit to the ASBC tables:
°P = 133.5892·SG3 − 622.5576·SG2 + 1102.9079·SG − 613.9427
Both fits reproduce the published tables to within a few thousandths of a degree, which is finer than a hydrometer or a refractometer can be read by eye.
Brix and Plato Are Nearly the Same Thing
Brix and Plato are both mass percentages, so they track each other closely — the difference is usually less than ±0.0005 and is ignored in practice. At SG 1.040, the reference tables give 9.993 °Bx and 9.994 °P. Winemakers and juice producers tend to use Brix; brewers tend to use Plato. For anything short of commercial trade, you can treat them as interchangeable.
Why Brix and SG Don't Scale Linearly
If the two scales were linearly related, the formula would be a single multiplication. They are not, for a physical reason: Brix is a mass percentage, while SG depends on volume. When sugar dissolves in water, the volume of the solution is not the sum of the water's volume plus the sugar's — dissolved sugar occupies less volume than its undissolved form.
Because that volume change is not proportional to the amount of sugar added, there is no clean algebraic conversion between a mass percentage and a density ratio. The relationship has to be measured in the lab, solution by solution, and then fitted with a curve. That is why the constants above look arbitrary, and why the cubic terms cannot be dropped without losing accuracy.
References: Brew Your Own magazine (Brix → SG); NBS and ASBC reference tables (SG → Brix, SG → Plato).
Brix to SG conversion chart — °Brix and °Plato to specific gravity
| °Brix | °Plato | Specific Gravity |
|---|---|---|
| 0 | 0.0 | 1.0000 |
| 3 | 3.0 | 1.0117 |
| 5 | 5.0 | 1.0197 |
| 10 | 10.0 | 1.0400 |
| 12 | 12.0 | 1.0484 |
| 14 | 14.0 | 1.0568 |
| 15 | 15.0 | 1.0611 |
| 20 | 20.0 | 1.0830 |
| 22 | 22.0 | 1.0920 |
| 25 | 25.0 | 1.1057 |
| 30 | 30.0 | 1.1292 |
At the one-decimal precision shown, the °Plato entries match the °Brix values. Wikipedia describes the scales as equivalent for most applications; their difference is generally under ±0.0005 °Bx or °P, except in weak solutions. References: Wikipedia, “Brix”.
Brix vs Plato vs Specific Gravity
These three scales all describe how much sugar is dissolved in a liquid and relate to the solution’s density. They express that relationship in different terms and were adopted by different industries.
Brix (°Bx) — Sugar as a Percentage of Mass
One degree Brix is one gram of dissolved solids per 100 grams of solution — a percentage by mass. A must reading 22 °Bx is 22% sugar by mass. Brix is the standard scale in winemaking, fruit juice, soft drinks and the sugar industry.
Plato (°P) — The Brewer's Mass-Percentage Scale
Plato also measures sucrose concentration as a percentage by mass. Brewers use °P, which is why brewing software often asks for it instead of °Bx. At SG 1.040, the reference tables give 9.99325 °Bx and 9.99359 °P — a difference of about 0.0003. The scales agree within ±0.0005 in almost every case; in very weak solutions, °P can read up to 0.002 higher near 0 °Bx. For most practical purposes, Brix and Plato are interchangeable: if a recipe calls for 12 °P, you can enter 12 °Bx.
Specific Gravity (SG) — Density Relative to Water
Specific gravity is not a sugar scale at all; it is a plain density ratio. Water at 20 °C is 1.000, so a wort reading 1.050 is 5% denser than water. Dissolved sugar is what makes it denser, which is why SG works as a stand-in for sugar content — but other dissolved solids push the number up too. SG is the default in both US and UK homebrewing, written either as 1.050 or, in the UK convention, as "1050".
How to Measure
Temperature matters when you measure Brix, Plato, or specific gravity. The standard reference is 20 °C/20 °C: the sample and the water reference are both at 20 °C. Hydrometer and saccharometer readings taken at another temperature must be corrected to the instrument’s calibration temperature using its correction table. Refractometer readings should also be taken at the temperature specified for the instrument or compensated within its stated range.
A refractometer’s “Brix” reading is not interchangeable with Brix derived from a hydrometer: it measures how the sample bends light and reports a sucrose-equivalent value, formally called Refractometric Dry Substance (RDS). Once fermentation starts, alcohol changes the refraction reading, so correct a fermented sample using both its original and current readings before estimating gravity. Temperature compensation does not correct for alcohol.
FAQ
Frequently Asked Questions
Quick answers about converting Brix, Plato, and specific gravity.
1
How to convert Brix to SG?
Use SG = °Bx ÷ (258.6 − (°Bx ÷ 258.2) × 227.1) + 1. For example, 22 °Bx is SG 1.0920. To convert SG to Brix, use °Bx = 182.46007·SG³ − 775.68212·SG² + 1262.7794·SG − 669.56218.
2
What is 1 Brix equal to?
1 °Bx is 1 g of dissolved sucrose per 100 g of solution (1% by mass), or about SG 1.0039.
3
What is the SG of sugar?
Dissolved sugar raises a solution’s SG: 10 °Bx is about 1.0400, while pure water is 1.000. These scales describe sugar dissolved in solution, not solid sucrose.
4
Is Brix the same as specific gravity?
No. Brix is sugar concentration by mass; SG is density relative to water. They are related, but convert between them rather than swapping the readings.
5
Is Brix the same as Plato?
For most brewing and winemaking, they are close enough to use interchangeably. The calculator’s fits give 9.993 °Bx and 9.993 °P at SG 1.040; small differences can grow at very weak or stronger solutions. Winemakers usually use Brix, brewers Plato.
6
How do I convert Plato to SG?
Use the converter’s ASBC based Plato fit: it solves the SG value corresponding to your °P reading. Brix and Plato are close at typical brewing strengths, but their fitted curves are not identical.
7
Do I need to temperature-correct my reading?
Yes. The formulas assume 20 °C/20 °C. Correct hydrometer readings to the instrument’s calibration temperature; even a 1 °C change can shift a reading, especially in beer.
8
Does a refractometer give the same Brix as a hydrometer?
No. A refractometer reports sucrose equivalent RDS, not hydrometer Brix. Wort may need a wort correction factor, and fermented samples need an alcohol correction because alcohol changes refraction.
9
What is 22 Brix in specific gravity?
22 °Bx is about SG 1.0920.
10
Is Brix, Plato & SG Converter free to use?
Yes. The converter is free to use online and does not require registration.