Wine Fermentation · Williams–Boulton Method

Fugitive Ethanol & CO₂ Calculator

Estimate fugitive ethanol and carbon dioxide generated during a red or white wine fermentation.

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Fermentation Inputs

Choose the unit combination you normally use. This preference is remembered on this device.
Keyboard: Enter advances to the next field; Shift+Enter moves back.

Batch

Fermentation

Sugar & Cap

Not applied White wine fermentation
The standard factor is automatically determined by wine type and selected temperature units.

Estimated Results

Complete all required fermentation fields.
Total fugitive ethanol —
Enter fermentation data to calculate.
Fugitive ethanol volume —
Estimated liquid ethanol equivalent.
Total carbon dioxide —
Temperature-adjusted gas volume.
CO₂-to-must volume ratio —
Gas volume : starting must volume.
Calculation details
Average fermentation temperature
—
Effective temperature with cap
—
Sugar consumed, ΔS
—
Fugitive ethanol concentration
—
Fugitive ethanol factor
—
The calculator's creator in a wine cellar with oak barrels

The double-glasses system is intentional: one pair helps me see, and the other protects my eyes from bright light. It may look like overengineering—but I am a retired engineer.

About the Creator

Experience Behind the Calculator

Retired mechanical engineer with more than 50 years of experience in ethanol capture and emissions control across several industries, including metal coating, printing and graphic arts, commercial baking, beer brewing, distilling, and winemaking.

The final 20 years of that work were spent in the wine industry, where this calculator was developed to simplify estimates of carbon dioxide generation and fugitive ethanol release during fermentation.

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About This Calculator

This calculator is based on research by Lynn Williams and Roger Boulton.

The Williams–Boulton model estimates fugitive ethanol from fermentation temperature and sugar consumption. Carbon dioxide production is estimated from sugar conversion and adjusted for the average fermentation temperature.

These results are intended as planning tools. Actual values may vary depending on yeast strain, nutrient availability, oxygen management, fermentation kinetics, and other winemaking variables.