Use this oenology calculation to document or plan a defined fermentation, blending, adjustment, stabilization, aging, packaging, sensory, or cellar operation from measured wine parameters.

A420

Absorbance at 420 nanometers, the browning end.

A520

Absorbance at 520 nanometers.

Compute the conventional red-wine hue ratio A420/A520 from spectrophotometer absorbances; despite the legacy route name, the result is a dimensionless ratio rather than an angle. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Hue ratio

Dimensionless A420 divided by A520.

• Wine chemistry and microbiology depend on temperature, pH, alcohol, sugar, matrix, measurement method, microbial state, legal limits, product formulation, and bench-trial response. Generic doses and thresholds are not production instructions for every wine.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Confirm measurements with calibrated winery methods, run scaled bench trials, record additions and lot volumes, check local regulations and supplier specifications, and obtain professional laboratory advice for faults or stability risks.

• Wine Color Density and Hue Calculator

  Calculate the conventional two-wavelength wine color density (A420 + A520) and hue ratio (A420/A520); these optical indices do not directly measure anthocyanin concentration.

• Red Wine Polymeric Pigment Index Checker

  Compare a polymeric-pigment assay result with a caller-selected threshold; crossing the threshold does not by itself establish long-term color stability.

• Ascorbic Acid Complement Dose Calculator

  Convert a user-selected ascorbic-acid treatment rate in milligrams per liter into total grams for a wine lot; determine the rate from an appropriate treatment plan rather than this arithmetic tool.