What This Calculator Does

This calculator helps home brewers determine the exact amount of priming sugar needed for bottle conditioning beer. When you bottle beer, you add a small amount of sugar to create natural carbonation through a secondary fermentation in the bottle. Getting this right is crucial because:

• Too little sugar = Flat, under-carbonated beer

• Too much sugar = Over-carbonation, potentially causing bottle explosions

• Just the right amount = Perfectly carbonated beer with the appropriate "head" and mouthfeel

The calculator uses scientific formulas to account for the CO₂ already dissolved in your beer (based on its temperature) and calculates how much additional CO₂ needs to be produced to reach your desired carbonation level.

Why Temperature Matters

CO₂ solubility in beer changes with temperature. Colder beer holds more dissolved CO₂ than warmer beer. If you cool your beer after fermentation (as many brewers do for clarity), CO₂ from the headspace dissolves back into the beer. This calculator uses the current temperature of your beer at bottling time to accurately determine how much CO₂ is already present, ensuring you don't over- or under-carbonate.

Required Inputs:

1. Volume Being Carbonated: Total beer volume for bottling (in liters).

2. Temperature Before Priming: Temperature of the beer at bottling time (in °C). If cooled after fermentation, use current temperature.

3. Target CO₂ Volumes: Desired carbonation level (typically 2.2–2.6 for ales, 2.5–2.7 for lagers).

Why Temperature Before Priming Matters

The formula calculates residual CO₂ already dissolved in your beer based on its current temperature:

• Warmer beer = Less dissolved CO₂ = More sugar needed

• Cooler beer = More dissolved CO₂ = Less sugar needed

Important Consideration

If you cooled your beer after fermentation, CO₂ from the headspace will have dissolved back into the beer while cooling. Using the current (lower) temperature accounts for this reabsorption.