About this tool
The Brix / Plato / SG Converter translates between the three sugar scales brewers and winemakers use: degrees Brix (°Bx, refractometer scale), degrees Plato (°P, common in professional brewing), and specific gravity (SG, the hydrometer scale). Pick which scale you are reading, type the value, and the tool returns the other two plus gravity points and an approximate potential ABV. Everything runs locally in your browser, so your measurements stay on your device.
The core relationship for Brix to specific gravity is SG = 1 + Bx / (258.6 − (Bx / 258.2) × 227.1). Going the other way uses the standard cubic SG-to-Brix fit Bx = 182.4601·SG³ − 775.6821·SG² + 1262.7794·SG − 669.5622, and Plato is derived from SG with −616.868 + 1111.14·SG − 630.272·SG² + 135.997·SG³. For practical wort, Brix and Plato are nearly identical (within about 0.1°). Gravity points are (SG − 1) × 1000, and potential ABV assumes the sugar ferments out completely, estimated as (SG − 1) × 131.25.
As a worked example, 12 °Bx converts to a specific gravity of about 1.048, roughly 48 gravity points, and a potential ABV near 6.3% if fermented dry. Note the potential-ABV figure is a maximum that assumes full attenuation to 1.000; real beers finish above 1.000, so the actual ABV is lower. Use the converter to move refractometer Brix readings into the SG your recipe software or hydrometer log expects.