# Priming sugar rates

I just checked out the NB priming calculator and it suggests to add a significant amount less of sucrose to a 5 gallon batch of beer at 39 degrees vs. 68 degrees. Anyone know why this is?

The solubility of CO2 in water (and therefore beer) increases as the temperature decreases. If a beer is kept cold it will retain more of the CO2 produced during fermentation.

When using one of those calculators, you want to enter the highest temperature the beer has reached during or after fermentation.

OK…but the calculator asks what the current temp of the beer is…in my case, I am cold crashing and planning to pull it out of the fridge to bottle. The highest it got was probably 66…should I enter that?

Yup. Heating a beer will remove CO2, but cooling it won’t have any effect. (Or at least very little.) So you always want to use the highest temperature.

Thank you so much for the advise…that makes sense now that I compare it to what I have done in the past.

A related question, what calculator do you use? I mostly keg but bottle for comps, family & friends. Have been using the HBD calculator but checked out several others and all have a different answer. HBD and Tastybrew seem to have the higher amounts of sugar to add. I have been trying to get consistent carbonation and have remarked volumes on the bottling bucket, racking to the bucket before measuring amount of beer & adding yeast at bottling.I also get a temp read with a good thermometer at bottling. This is the only inconsistent part of the process that I can think of.

Sorry did not mean to highjack, seemed like a good thread to ask. Mike.

Have you double-checked for typos? It’s a very simple calculation.

Just as an example, I plugged 2.7 vol CO2, 5.5 gal, 68°F into several of them:
NB: 5.46 oz
TastyBrew: 5.4 oz
HBD Recipator: 5.43 oz
KOTMF: 5.43 oz
BeerTools Pro: 5.43 oz

That’s for corn sugar. Switching to cane sugar, they again all give the same result, except for NB’s (which subtracts 10% instead of 5% for no particular reason I’m aware of).

I checked the numbers for 2.5 vol co2 @ 70*F with cane sugar, which I use. They were Tasty Brew with 4.3oz, HBD 4.25, and then Northern Brewer 4.10 and Brew Heads 4.13. This is what I was talking about although it doesn’t seem like that much difference.I sometimes over figure things because I like math. Thanks for the reply a10t2.