reliable priming sugar calculators

[coolbeerluke]

Prior to my current batch of beer, I used to old 3/4 cup of sugar with 2 cups of water (boiled) method for priming sugar. But now, I want to take a little more control over carbonation and figure out how much priming sugar I should actually be using. Problem is, I've been to four different calculators on the net and each of them came up with different amounts: between 2.8 and 4.5 ounces of priming sugar. any suggestions?

And my inputs are,

Name: Nut Brown Ale
Beer: 5 gallons
Fermentation Temp: 68 degrees F
CO2 volume: 1.9
Sugar type: corn sugar

 

[Parker36]

I always use the one in beersmith and it hasn't served me wrong yet. They have a free trial, you should check it out. its worth the $15

 

[emoutal]

Beersmith works well, but so does this one The Beer Recipator - Carbonation