It depends. Are you msking 1,3 or 5 gallons? Whay size cinnamon stick are you using? In a three gallon batch I generally put in 2-3 sticks that are about 2.5 inches in length. ellpout is right. start slow.....you can always add more but you can't take it out once it is in there
I made a 6 gallon batch. The sticks I have are about 2.5 in in length as well. So I'm thinking about 4 or 5 then. I want a subtle cinnamon flavor, not a smack you in the face flavor. I'll probably start off with 4 and see how it tastes after a week.