🔬 Brix to Gravity Calculator
Translate a refractometer °Brix reading into specific gravity — or convert an SG back to °Brix — so your hydrometer and refractometer measurements always line up.
🔬 Convert Brix ↔ Gravity
What is a Brix to Gravity Calculator?
It bridges the two ways brewers measure sugar in their wort. A refractometer reports °Brix from just a few drops, which is perfect for quick pre-boil checks, while recipes and hydrometers speak in specific gravity. This tool converts cleanly between them in either direction.
Enter a Brix value to get the equivalent SG, or an SG to get the Brix, using the standard homebrew conversion polynomials. Note that the conversion holds only for unfermented wort — once alcohol is present a refractometer reads high, so use this for pre-fermentation measurements and keep a hydrometer for tracking fermentation to completion.
❓ Frequently Asked Questions
How does the Brix to gravity calculator work?
It converts between the two scales brewers use to measure sugar. To go from °Brix to specific gravity it applies the standard polynomial SG = 1 + brix ÷ (258.6 − (brix ÷ 258.2) × 227.1); to go the other way it uses the inverse cubic that maps SG back to °Brix. Pick a direction, enter your value, and it returns the equivalent reading.
What's the difference between Brix and specific gravity?
Both measure dissolved sugar in wort but on different scales. °Brix is the percentage of sugar by mass, read on a refractometer from a few drops of liquid. Specific gravity is the density of the wort relative to water, read on a hydrometer from a larger sample. This tool lets you move between the refractometer and hydrometer worlds.
Can I use a refractometer after fermentation starts?
Not directly. Alcohol has a different refractive index than sugar, so once fermentation begins a refractometer's °Brix reading is skewed and won't convert cleanly to true gravity. This calculator is for unfermented wort — measuring pre-boil and original gravity. To track gravity during fermentation with a refractometer, you need a separate alcohol-corrected formula.
Why do refractometer and hydrometer readings sometimes disagree?
Small differences come from calibration, temperature, and the wort's exact composition — the conversion formulas assume a typical sucrose-like solution, but real wort has maltose and other sugars. A refractometer is handy for quick pre-boil checks on tiny samples, while a hydrometer is the reference for original and final gravity; keep them consistent within a batch.