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info Overview

Work out the corn sugar or table sugar needed to bottle-condition beer from batch volume, temperature, and a target of 1.5-4.0 CO2 volumes.

📘 How to Use

  1. Enter your beer volume (total at bottling, default 19 L)
  2. Enter the highest temperature reached after fermentation
  3. Pick your target CO2 with the slider
  4. Read the corn sugar and table sugar amounts

Priming Sugar Calculator

L
°C

Use the highest temp reached after fermentation for accurate residual CO2

2.4 vol
1.5 4.0

Style guide: lagers 2.4-2.6, ales 1.8-2.4, wheat beers 3.0-4.0

science Results

Corn sugar (dextrose)

— g

Table sugar (sucrose)

— g

Residual CO2

— vol
warning

Too much sugar over-pressurizes the bottle and can cause it to burst. Keep the target within the style range, use pressure-rated bottles, and store somewhere cool.

※ Residual CO2 uses the standard temperature formula (3.0378 - 0.050062·T + 0.00026555·T², T in °F)

※ Corn sugar (dextrose) yields ~0.49 g CO2 per g, sucrose ~0.51 g per g; dextrose gives less CO2 per gram, so it needs more grams for the same carbonation

※ Assumes a fully fermentable priming sugar and estimates residual CO2 at the highest temperature reached after fermentation; actual results vary with temperature history and yeast

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Article

Priming Sugar Calculator | Bottle-Conditioning Sugar by Volume and Temperature

Work out how much sugar to add when bottling homebrew for natural carbonation, from batch volume, beer temperature, and a target CO2 level. Shows both corn sugar (dextrose) and table sugar (sucrose), and subtracts the temperature-dependent residual CO2 automatically.

💡 About this tool

Too little priming sugar leaves you with flat beer; too much over-pressurizes the bottle. The tricky part is that fermented beer already holds dissolved CO2, and how much it holds depends on temperature. Beer that finished at 20 C and beer that finished at 10 C need different sugar additions to reach the same fizz.

This calculator uses the standard homebrew formula: it estimates residual CO2 from the highest temperature your beer reached, then converts only the gap to your target into sugar. Corn sugar releases slightly less CO2 per gram than sucrose, so it needs a few more grams for the same carbonation. Both numbers are shown side by side, so you can dose with whatever is in the cupboard.

🧐 Frequently Asked Questions

What is residual CO2? The CO2 made during fermentation that stays dissolved in the beer. Colder beer holds more. Subtracting it from your target gives the gap the priming sugar has to fill.

Which temperature do I enter? The highest temperature your beer reached after fermentation. The warmest point sets the floor for residual CO2, so using it keeps the estimate on the safe side.

Corn sugar or table sugar — does it matter? Both ferment completely. Corn sugar (dextrose) carries some water, so it takes a few more grams for the same fizz; table sugar (sucrose) takes a touch less. The numbers already account for the difference.

What target CO2 should I use? Lagers 2.4-2.6, ales 1.8-2.4, wheat and Belgian styles 3.0-4.0 are typical. Pushing past the top of a style's range invites over-carbonation.

Could a bottle explode? It can if you over-prime. Keep the target inside the style range, use pressure-rated bottles, and store them somewhere cool.

📚 Fun Facts

Homebrewers on r/Homebrewing argue endlessly about cups versus grams — and the cup measure is exactly why bottle bombs happen, since a "cup" of corn sugar weighs noticeably less than a cup of table sugar. The classic priming math traces back to the temperature regression popularized in brewing references, which captures how CO2 solubility falls as beer warms. Once you cap a primed bottle, you have built a tiny fermenter that quietly pressurizes itself for two weeks.