Specific Gravity to Brix Converter
The SG-to-Brix conversion is the inverse of the ICUMSA Method GS4-13 polynomial. The ICUMSA polynomial is calibrated for the 0-30°Bx range typical of winemaking, brewing, and most...
Formula
Source: ICUMSA Method GS4-13 (2009); ASBC Methods of Analysis (Beer-2B) | Last reviewed: July 3, 2026
Examples
1.0484 SG
= 12 brix
Typical beer OG (12°Bx)
1.0833 SG
= 20 brix
Typical white wine must (20°Bx)
1.105 SG
= 25 brix
Typical red wine must (25°Bx)
1.1773 SG
= 40 brix
Fruit juice concentrate (40°Bx)
Quick Reference Table
| Specific Gravity (SG) | Brix (°Bx) | Sugar (g/L) | Industry |
|---|---|---|---|
| 1 | 0 | 0 | Pure water |
| 1.0198 | 5 | 51.5 | Light beer |
| 1.0401 | 10 | 104 | Standard beer |
| 1.0484 | 12 | 125.7 | Beer OG |
| 1.0608 | 15 | 158.5 | Strong beer |
| 1.0833 | 20 | 215.2 | White wine |
| 1.105 | 25 | 270 | Red wine |
| 1.2317 | 50 | 537.3 | Maple syrup |
| 1.3222 | 65 | 720.4 | Corn syrup |
Where is this used?
In brewing, Original Gravity (SG 1.030-1.080 for most styles) is converted to Brix for fermentation tracking and ABV calculation.
In winemaking, specific gravity readings from hydrometers are converted to Brix for harvest decisions and fermentation monitoring.
In sugar refining, SG measurements from process density meters are converted to Brix for process control.
In the food industry, SG of syrups, concentrates, and sweetened beverages is converted to Brix for product specification and quality control.
The reverse ICUMSA polynomial is the standard conversion method across all these industries.
Real-World Usage Scenarios
Brewpub Hydrometer Reading
A brewpub brewer measures the cooled wort with a hydrometer reading 1.058 at 18°C. Per ASBC Beer-2B, the temperature correction is -0.0002 SG/°C from 20°C, so the corrected reading is 1.0576. Converting to Brix: Br = 258.6 × ((1.0576 - 1) / (258.6 - 227.1 × (1.0576 - 1))) = 13.6°Bx. The target was 15°Bx, indicating mash efficiency is below target. The brewer adds DME to adjust.
Winery Harvest Monitoring
A California winery takes hydrometer readings in the vineyard at 1.092 SG at 22°C ambient. Temperature-corrected to 20°C: 1.0916. Converting to Brix: approximately 22.1°Bx. The target for Pinot Noir harvest is 24-26°Bx, so harvesting is delayed 3-5 days depending on the forecast.
Common Mistakes to Avoid
Forgetting hydrometer temperature correction
A hydrometer reading of 1.050 at 25°C is not 1.050 at 20°C. The uncorrected reading gives 12.4°Bx, but the corrected reading (1.0488) gives 12.1°Bx — a 0.3°Bx difference that changes the predicted ABV by 0.15%. Always apply temperature correction per the hydrometer manufacturer's chart.
Assuming SG-to-Brix is a linear conversion
SG 1.040 → 10°Bx and SG 1.080 → 20°Bx are NOT linear. The difference from linear behavior is significant: SG 1.040 × 2 = 1.080, but 10°Bx × 2 = 20°Bx gives SG 1.0833, not 1.080. The polynomial is non-linear — never use SG × constant to estimate Brix.
Industry Standards Referenced
Frequently Asked Questions
How do I convert a hydrometer reading to Brix?
First, apply temperature correction to the hydrometer reading (most hydrometers are calibrated at 20°C). Then use the ICUMSA inverse formula: Brix ≈ 258.6 × ((SG - 1) / (258.6 - 227.1 × (SG - 1))). Example: SG 1.0484 → Brix ≈ 258.6 × (0.0484 / (258.6 - 227.1 × 0.0484)) = 258.6 × (0.0484 / 247.6) = 12.0°Bx.
What is the difference between hydrometer and refractometer Brix readings?
A hydrometer measures true SG at the current temperature. A refractometer measures refractive index, which is converted to Brix using a sucrose calibration. For unfermented solutions (pure sugar solution), hydrometer and refractometer agree. After fermentation begins (alcohol present), the refractometer reads HIGH because alcohol has a different refractive index than water — this requires a separate refractometer correction formula.
Why does my hydrometer Brix not match my refractometer Brix after fermentation?
Alcohol from fermentation skews the refractometer reading. A refractometer calibrated for pure sucrose will read artificially high when alcohol is present. The fix is to apply the refractometer correction formula (e.g., the Terrill formula or the official ASBC correction) before comparing to the hydrometer. Never use an uncorrected refractometer for FG.
Reviewed for accuracy
Cross-referenced against ICUMSA inverse polynomial and ASBC standard methods · Last reviewed: July 3, 2026
All calculations are for reference only. Always verify with manufacturer data and a qualified engineer for critical applications. Learn about our editorial process.