Priming sugar — bottle conditioning

Calculate the table-sugar (sucrose) addition needed at bottling to reach a target CO₂ carbonation level.

Formula

Residual_CO2 = 3.0378 − (0.050062 × T_F) + (0.00026555 × T_F^2)
Sugar_g_per_L = (Target_vols − Residual_CO2) × 4
where T_F is fermentation temperature in °F (use highest temp the beer reached after primary).

Inputs

Name	Unit	Description
T_F	°F	Maximum fermentation temperature post-primary (in °F; convert from °C as F = C × 9/5 + 32)
V_target	vol CO₂	Target carbonation in volumes (1 vol = 1 L gaseous CO₂ per 1 L beer at STP)
V_batch	L	Volume of beer being primed

Outputs

Name	Unit	Description
sucrose	g	Total sucrose mass to dissolve in boiled water and add to bottling bucket

Worked example

Inputs:

T_F = 68
V_target = 2.4
V_batch = 19

Calculation:

Residual_CO2 = 3.0378 − (0.050062 × 68) + (0.00026555 × 68²) = 3.0378 − 3.404 + 1.228 = 0.86 vol Sugar/L = (2.4 − 0.86) × 4 = 6.16 g/L Total = 6.16 × 19 = 117 g

Result:

Boil 117 g table sugar in 200 mL water, cool, add to bottling bucket

Sample values

Style	Target vol CO₂	g/L (at 20 °C ferment)
British cask ale	1.5	2.6
Standard ale	2.4	6.2
American IPA / pale	2.5	6.6
German lager	2.7	7.4
Belgian saison / tripel	3.5	10.6
Hefeweizen	3.6	11

What residual CO₂ is

Beer that finishes fermenting at 20 °C (68 °F) has roughly 0.86 volumes of CO₂ already dissolved in it from primary fermentation. The priming sugar only needs to push from that residual level up to the target level.

Beer that finished fermenting cold (a lager at 4 °C) carries much more residual CO₂ (~1.5 vol) and needs much less priming sugar.

Beer that finished warm (a Belgian fermented up to 24 °C) carries less residual CO₂ and needs more priming sugar.

Alternative sugars

The formula uses sucrose. For other sugars, multiply the gram count by:

Sugar	Factor
Sucrose (table sugar)	1.0
Corn sugar (dextrose)	1.1
Light DME	1.5
Honey	1.2

Practical safety note

Most beer bottles are rated for ~3-4 vol CO₂. Hefeweizens and tripels routinely exceed that — use thick-walled champagne or Belgian bottles for high-carbonation styles, not standard pry-off bottles. Failure modes include both leaking and dramatic glass shrapnel events.