Gravity ↔ Brix Converter
Convert specific gravity (SG) to Brix and back, instantly, for must, wort or juice before fermentation begins.
Brix
12.4°Bx
For unfermented must, wort or juice only: once fermentation starts, alcohol throws off the Brix reading.
How it works
This converter uses a standard cubic polynomial approximation for SG → Brix, and its inverse for Brix → SG. That plain conversion is accurate for unfermented liquids only; once alcohol is present, a refractometer reading needs a separate alcohol correction, which the Brix → SG side of this tool can optionally apply.
Use it to double-check a reading, switch between a hydrometer scale and a refractometer scale, or plan a target original gravity in whichever unit your recipe uses.
Correcting a mid-fermentation Brix reading
A refractometer reads dissolved sugars by how they bend light, but alcohol bends light too — so once fermentation starts, a raw Brix reading runs high and no longer reflects the real gravity. Enter your original Brix (taken before pitching) alongside your current reading and this tool applies Sean Terrill’s cubic correction formula to back out the true specific gravity.
SG = 1.0000 − 0.0044993·OBrix + 0.011774·FBrix + 0.00027581·OBrix² − 0.0012717·FBrix² − 0.0000073·OBrix³ + 0.000063293·FBrix³
Where OBrix is your original Brix and FBrix is your current Brix reading (both divided by a wort correction factor of 1.04 first). It’s most accurate once fermentation is well underway — above roughly 60% apparent attenuation — and is the same correction used by most brewing refractometer calculators.
SG to Brix quick reference
Common specific gravity readings and their Brix equivalent, for unfermented must, wort or juice.
| SG | Brix |
|---|---|
| 1.000 | 0.0°Bx |
| 1.010 | 2.6°Bx |
| 1.020 | 5.1°Bx |
| 1.030 | 7.6°Bx |
| 1.040 | 10.0°Bx |
| 1.050 | 12.4°Bx |
| 1.060 | 14.7°Bx |
| 1.070 | 17.1°Bx |
| 1.080 | 19.3°Bx |
| 1.090 | 21.6°Bx |
| 1.100 | 23.8°Bx |
| 1.110 | 25.9°Bx |
| 1.120 | 28.1°Bx |
Frequently asked questions
What is the difference between SG and Brix?
Specific gravity (SG) measures the density of your liquid relative to water (e.g. 1.050). Brix measures the percentage of dissolved sugar by weight (e.g. 12.4°Bx). Both describe roughly the same thing: sugar content before fermentation, just on different scales, so hydrometers and refractometers may report either one.
Can I convert Brix to SG after fermentation has started?
Not accurately with a plain conversion, but you can with a correction. Once alcohol is present, a refractometer reading needs an alcohol correction (Brix readings run high once alcohol is present). Enter your original Brix reading in the optional field on the Brix → SG converter above and it will apply Sean Terrill's cubic correction formula, which is accurate for both mid-fermentation and final gravity readings.
Why do my hydrometer and refractometer disagree slightly?
Small differences are normal: refractometers and hydrometers use different physical principles and calibration temperatures. This converter uses a standard cubic polynomial approximation that matches most brewing references closely enough for everyday use.
Related tools
Track the whole batch, not just the math
Fermolog logs your gravity readings, ABV, notes and photos automatically as you go. Download the free app to keep every batch in one place.