Tool
What does my refractometer reading mean in SG?
Converts a refractometer reading to specific gravity, and says clearly why the reading stops being trustworthy the moment fermentation begins.
Brix to specific gravity
Apple juice is normally 10–18 °Bx.
Specific gravity
1.053
How this is worked out
- Formula: SG = 1 + Bx ÷ (258.6 − ((Bx ÷ 258.2) × 227.1))
- Substituted: SG = 1 + 13.0 ÷ (258.6 − ((13.0 ÷ 258.2) × 227.1))
- Result: SG ≈ 1.053
What this assumes (2)
- Brix is calibrated on sucrose. Apple and pear juice contain fructose, glucose, sucrose and — in pears — sorbitol, so the conversion is close rather than exact.
- A refractometer reading is only valid on juice that has not started fermenting. Ethanol bends light differently and makes a fermenting sample read high; use a hydrometer once fermentation has begun.
Related tools
Where this reading comes from
Guides that reach this calculator, and what the number decides once you have it.