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SG to Plato and Brix gravity converter
°Brix = 182.4601·SG³ − 775.6821·SG² + 1262.7794·SG − 669.5622, and °Plato is effectively the same number. SG 1.048 is about 11.9 °P, and 12 °P is about SG 1.048.
BrewMyBeer Editorial Team · Sources checked 24 September 2026 · Calculated examples, not laboratory measurements. How we create content
Interactive tool
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One polynomial, both directions
The SG-to-Brix cubic above is quoted in Wikipedia’s Brix article for apparent specific gravity at 20 °C/20 °C. The tool solves the same equation backwards for °Plato or °Brix to SG, so converting a value and converting it back gives the number you started with.
The same article says Plato and Brix are, for all but the most exacting purposes, the same: the difference is generally under 0.0005°. The tool therefore shows one value for both.
Unfermented samples only
Alcohol changes both density and refraction. Once fermentation has started a refractometer reads high, so a fermented reading needs a correction based on the original reading rather than a straight conversion. Use the refractometer correction calculator for that.
Hydrometer readings should be taken at, or corrected to, the instrument’s calibration temperature before converting.
Before you use the result
- Convert unfermented wort, juice or must only.
- Correct hydrometer readings for temperature first.
- For adults of legal drinking age. This tool describes a drink or batch, not its effect on a person.
A quick learning check
Why can’t you convert a refractometer reading taken after fermentation straight to SG?
Try a craft decision game →Sources & further reading
These references explain the methods and limitations. The worked examples and learning questions on this page are BrewMyBeer calculations, not claims of hands-on testing.