As Conor says you can only be certain of the click settings for your particular setup by shooting at paper! Chairgun will give you a starting point but I've found that two things really affect it's accuracy. 1) do not use the BC given, set two chrono's up one in front of the muzzle and one down range (ideally at 55yds) then work out the BC for your particular pellet/barrel. 2) if you are using a sloped rail where do you measure the scope height? I usually measure in the middle and then tweak it to suit. Why fanny about with all that when it's easier to do it properly
I repeat the only way to be certain is on paper on a calm day!