Krausening and Speise Calculator

Calculate how much speise, gyle or krausen to add when you bottle or keg, instead of priming sugar, from the target carbonation and the gravity of the wort.

Speise, gyle or krausen replace priming sugar with wort that still has gravity points to ferment. 20 L of beer that needs 131 g of corn sugar for 2.5 volumes takes about 1.27 L of speise at 1.048 that will finish at 1.012, or about 2.5 L of krausen already down to 1.030.

Reviewed by Diego Santiago, Professional Brewer

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Speise or gyle (unfermented wort)Krausen (fermenting beer)

Target carbonation (vol)

Volumes of CO₂, e.g. 2.5 for most ales and lagers

Beer temperature (°C)

Warmest temperature the beer reached after fermentation

Beer volume (L)

Volume of beer you are packaging

Wort gravity (SG)

Gravity of the wort you saved

Final gravity of that wort (SG)

Usually the final gravity of the beer it came from

Speise or gyle to add1.27LShare of the beer volume6.4%Replaces this much corn sugar131g

Results are estimates provided "as is," for informational and planning purposes only, without warranties of any kind. Check them before you rely on them: you are responsible for decisions about your beer and equipment, including pressure and carbonation levels, the pressure ratings of your kegs and fittings, and any alcohol content you declare. Use of this calculator is subject to our Terms and Conditions.

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How the wort volume is calculated

The calculator first works out the corn sugar that would reach your carbonation, with the same calculation as the priming sugar calculator. It then finds the wort that ferments to the same amount of CO₂.

Two fermentables give the same carbonation when their weight × extract yield × fermentability is the same, the equivalence John Palmer uses for priming sugars. For wort, each liter brings the gravity points it will still lose, so:

V = \frac{m \times P}{G - FG}

where $V$ is the wort to add in liters, $m$ the corn sugar in kilograms, $P$ the potential of corn sugar (42 PPG, about 350 L°/kg), and $G$ and $FG$ the gravity of the wort now and its final gravity, in points.

For example, 20 L of beer that reached 20 °C and should be carbonated to 2.5 volumes needs 131 g of corn sugar. Speise at 1.048 that will ferment down to 1.012 gives 36 points per liter, so add about 1.27 L (6.4% of the beer). Krausen already down to 1.030 has only 18 points left, so it takes about 2.5 L.

Inside Foambyte, each batch’s carbonation stage records how you carbonate, from priming to force carbonation.

Reference table

Liters of wort to add per 20 L of beer by wort gravity (rows) and CO₂ volumes to add (columns), wort fermenting down to 1.010
Wort \ CO₂ to add	+1.00 vol	+1.25 vol	+1.50 vol	+1.75 vol	+2.00 vol
1.030	1.40	1.75	2.10	2.45	2.80
1.040	0.93	1.17	1.40	1.63	1.87
1.045	0.80	1.00	1.20	1.40	1.60
1.050	0.70	0.87	1.05	1.22	1.40
1.055	0.62	0.78	0.93	1.09	1.24
1.060	0.56	0.70	0.84	0.98	1.12
1.070	0.47	0.58	0.70	0.82	0.93
1.080	0.40	0.50	0.60	0.70	0.80

Sources

John J. Palmer. How to Brew, Brewers Publications, 2006. Equivalence between priming sugars (weight × extract yield × fermentability) and the extract yield of corn sugar (chapter 11, table 13); 3rd edition, online version with the author's updates.

Frequently asked questions

What are speise, gyle and krausen?

Speise and gyle are unfermented wort from the same brew, saved to prime the beer when it is packaged. Krausen is beer taken from a fermentation that is still active and added to finished beer. All three carbonate the beer with its own malt sugars instead of added sugar.

Which final gravity should I enter?

The gravity the saved wort or krausen will ferment down to, which is usually the final gravity of the beer it came from. The calculator counts only the gravity points still left to ferment.

How do I store speise until bottling day?

Boil it, cool it in a sanitized, sealed container and keep it cold, ideally frozen. Wort spoils easily, so bring frozen speise back to a boil, cool it and add it just before packaging.

Why does krausen need more volume than speise?

Krausen has already fermented part of its sugar, so each liter has fewer gravity points left to give. The further the fermentation has gone, the more krausen you need for the same carbonation.

Does the added wort change my beer?

It adds a few percent of volume and a little fresh fermentation, which many brewers value in lagers. Because the amount is small and it is the same wort, the flavor change is usually slight.